Welcome to the Huberman Lab Podcast,

where we discuss science

and science-based tools for everyday life.

I’m Andrew Huberman,

and I’m a professor of neurobiology and ophthalmology

at Stanford School of Medicine.

Today, we are discussing caffeine.

Caffeine is one of the most widely used substances

on the planet.

Estimates are that more than 90% of adults

and as many as 50% of kids,

that is adolescents and teenagers,

use caffeine on a daily basis.

Caffeine is an amazing molecule.

Most people are familiar with caffeine’s ability

to increase alertness

and to reduce our feelings of sleepiness and fatigue.

And indeed, it does that.

But what most people are not aware of

is that caffeine acts as a strong reinforcer.

What I mean by reinforcer

is that when caffeine is present in a drink or food,

and yes, indeed, caffeine is present in many foods,

even unbeknownst to us,

when it’s present in drinks and foods,

we actively come to like those foods and drinks more

than if caffeine were not contained

in those foods and drinks.

So it reinforces our liking

of particular foods and drinks,

and indeed, it even reinforces our liking

of the containers they are consumed from

and the company we keep

when we consume foods and drinks that contain caffeine.

That is, caffeine is not just a stimulant.

Caffeine is a reinforcer,

and it’s a reinforcer that plays an active role

in almost everybody’s daily life.

We can say that with confidence

because as I mentioned a moment ago,

more than 90% of people are consuming caffeine,

and most people think that they consume caffeine

because it makes them feel more alert.

But there are many reasons why you’re consuming caffeine,

and I’m not going to tell you

that consuming caffeine is necessarily bad.

In fact, today, I’m going to tell you

about many of the positive health benefits of caffeine,

including neuroprotective effects,

antidepressive effects,

and certainly performance-enhancing effects,

both for mental performance and for physical performance.

Now, that said, there are certain situations

in which you want to avoid caffeine,

and there are certain people who might opt to avoid caffeine.

That’s especially the case when one thinks about caffeine

not just as a stimulant, but as a reinforcer.

In fact, caffeine is such a strong reinforcer

that if even tiny amounts of caffeine are present

in certain foods and drinks,

you will very quickly come to prefer those foods and drinks

over other choices,

which can be a good thing or a bad thing,

depending on what sorts of food and drink choices

you’re trying to make.

So today, I’m going to inform you

about how caffeine works at a mechanistic level.

I promise to do that with a minimum of nomenclature

and such that even if you don’t have a background

in biology, you will be able to digest

that information easily.

And then I’ll tell you how to use caffeine

to your advantage, or conversely,

how to avoid caffeine at certain times to your advantage.

So today’s episode will focus both on mechanisms and tools

that is the use and leverage of caffeine

to improve mental health, physical health, and performance.

Before we go any further into today’s discussion,

I want to tell you about some recent results

about a molecule that’s found

in certain caffeinated beverages,

and that has been proven to be very useful

for both weight loss, mental performance,

and controlling blood sugar levels.

And that’s GLP-1, or glucagon-like peptide one.

Glucagon-like peptide one is found in the brain and body.

It acts both on the brain and body.

It does many different things,

but one of its primary effects it’s been discovered

is to reduce hunger, and it does that two ways.

It does that by activating certain neurons

in your hypothalamus, so that’s a brain region

that controls hunger and satiety.

It makes us feel full at the level of the brain,

so it makes us feel sated, that is,

and it actually makes us feel full.

Turns out that GLP-1 acts on certain receptors in the gut

to make us feel as if we’ve ingested enough food.

It doesn’t necessarily make us feel

as if our gut is distended, but it makes us feel full.

That’s really interesting because if you think about it,

when we eat, our stomach fills up, obviously,

and that information has to be communicated to the brain

such that the brain can then send satiety signals

that actually shut off our hunger.

And believe it or not, the brain actually activates signals

to reduce the desire to chew when our stomach is full.

And GLP-1, as I mentioned, works on the brain

to create these feelings of satiety,

as if we’ve had enough,

and to reduce our desire to eat more.

And GLP-1 acts directly on the gut

to give us a slight sense of fullness in the gut,

which then is communicated to the brain.

So really, there are two parallel signals being sent

when we have GLP-1 present in our system.

Now, a little bit of relevant history on GLP-1.

It was actually discovered in Gila monsters.

These are these reptiles

that can go long periods of time without eating,

and a very clever scientist decided to study why it is

that certain animals, like Gila monsters,

can go a long period of time without ingesting anything.

And it’s because they produce very large amounts of GLP-1.

They isolate the peptide from GLP-1,

then they looked for the analogous peptide in humans,

and it turns out that does exist.

And as I mentioned, it’s released in both brain and body

to make you feel full and sated.

Why am I telling you all this?

Well, today we’re going to talk about caffeine,

and there’s one particular caffeine source,

which is yerba mate.

And there’s some other forms of teas,

similar to yerba mate,

that stimulate the release of GLP-1 significantly.

There are also nowadays drugs

which are called analogs of GLP-1.

So these are drugs that mimic or are identical

to the kind of GLP-1 that you would make.

And those drugs are proving to be very effective

for the treatment of certain forms of diabetes

and for the treatment of obesity.

But they trigger enormous amounts

of GLP-1 pathway activation.

So those are extreme cases for people

that are really struggling for weight loss.

But the clinical trials and the data that are out there

in the general population now are very, very promising

for GLP-1 analogs.

Yerba mate tea, provided it’s not the smoked variety,

and I mentioned that because a number of people

have cued me to the fact that yerba mate teas

come in smoked varieties and non-smoked varieties,

and the smoked varieties are thought

to perhaps be carcinogenic, that is pro-cancer causing.

So I advise people to avoid smoked varieties

of yerba mate tea.

But yerba mate teas are known to stimulate

significant amounts of GLP-1 release.

And so they can be effective as a weight loss tool,

mainly by blunting appetite.

And again, they do that both at the level of the brain

and at the level of the gut.

Now, all of what I just told you has been known

for some period of time, but there are a new set of findings

that were just published in Cell Reports Medicine,

Cell Press Journal, excellent journal,

which indicate exactly how it is that GLP-1

stimulates both satiety and can trigger additional weight

loss through other mechanisms.

And I find the mechanism to be really interesting

and actually really important, given some other topics

we’ve covered on this podcast before.

So the basic finding is that GLP-1,

whether or not it’s stimulated through the release

of a analog drug that one is prescribed

or by drinking yerba mate tea, for instance,

and stimulate release of your own so-called endogenous GLP-1,

yes, it makes you feel more full

at the level of brain and body,

but it turns out it also stimulates thermogenesis.

Now, thermogenesis is the active utilization

of more metabolic energy.

And fat cells, in particular,

so-called beige and brown fat cells

are a potent source of thermogenic activity in your body.

The basic background is that you have white adipose cells,

so white fat cells, you have beige fat cells,

and you have brown fat cells.

And the beige and brown ones are fat cells

that you actually want more of.

They are not abundant under your skin,

they’re abundant really around your clavicles

and your upper neck.

They are the ones that generate heat

and the beige and brownness of them

is actually the consequence

of having a lot of mitochondria in those cells.

When GLP-1 is elevated in your system,

it turns out that it communicates to those white fat cells

and helps convert them into beige and brown fat cells.

That is, it takes fat cells

that are not doing anything useful for you

except being stored energy.

And I think most people out there

would like to have fewer of those white adipose cells.

There are a few of you out there

that actually need more of them,

that are too thin, too lean,

but most people are suffering

from having too many of these white adipose cells.

Well, when you ingest yerba mate tea

or you were to take a GLP-1 analog

or stimulate GLP-1 in any number of different ways,

yes, you stimulate increased satiety,

but you’re also stimulating the conversion

of these white fat cells into beige and brown fat cells,

which makes you more thermogenic

and over time raises your basal metabolic rate.

So you’re burning more calories even at rest.

It also makes you feel as if you’re more comfortable

in colder environments at rest.

This is very much the same as the mechanism

that’s induced when you were to say, take a cold shower

or do regular ice baths or get into cold water regularly.

That too stimulates the conversion of white fat cells

to beige and brown fat cells.

So I like these findings very much

because they provide a mechanistic coherence.

They provide that is a really nice story

as to how something like GLP-1

could be so effective for weight loss.

Yes, on the one hand, GLP-1 is reducing appetite

and that of course will help people maintain or lose weight,

but it’s also increasing basal metabolic rate.

And we now know how that’s accomplished.

It’s likely accomplished at least through this one mechanism

by the stimulation of conversion of these white fat cells,

which don’t do much for us except as energy storage units

to these metabolically mitochondrial rich beige

and brown fat cells,

which you can think of as sort of the oil in the candle

that allows your furnace, your metabolism to burn

at a higher temperature and a higher rate.

So that’s the mechanism.

And the basic tool takeaway is that

if you are somebody who’s interested in losing weight

and you want to leverage the GLP-1 pathway,

drinking a cup or two of yerba mate tea early in the day

would be a great way to stimulate GLP-1 release.

There are other ways to stimulate GLP-1 release.

You can get it through certain forms of exercise,

in particular fasted exercise.

This is actually a vote in favor of fasted exercise.

There’s a debate as to whether or not fasted cardio

burns more fat than non-fasted cardio.

And the data basically say, no, it doesn’t really matter,

but that doesn’t really take into account

the longer arc of things like GLP-1 release.

So that needs to be taken into consideration.

So you could do fasted cardio,

you could drink yerba mate tea,

keeping in mind that yerba mate tea does contain caffeine.

We’ll talk more about the specific forms of stimulants,

including caffeine that mate has.

But mate would be a great way to stimulate GLP-1 release.

And then of course, for those of you that are interested

in more robust activation of GLP-1,

then perhaps you might want to consider

some of the new prescription GLP-1 analogs

that are out there,

but that’s a more severe stimulus for GLP-1, of course.

And for everybody, regardless of whether or not

you’re trying to lose weight, gain weight, or maintain weight

I think we’re going to be hearing a lot more

about GLP-1 analogs and drinks and supplements

and things of that sort that stimulate GLP-1

in the very near future,

because it does appear to be a very important

biological mechanism.

Before we begin, I’d like to emphasize that this podcast

is separate from my teaching and research roles at Stanford.

It is however, part of my desire and effort

to bring zero cost to consumer information about science

and science related tools to the general public.

In keeping with that theme,

I’d like to thank the sponsors of today’s podcast.

Our first sponsor is Element.

Element is an electrolyte drink with everything you need

and nothing you don’t.

That means plenty of salt, magnesium, and potassium,

the so-called electrolytes, and no sugar.

Now, salt, magnesium, and potassium are critical

to the function of all the cells in your body,

in particular to the function of your nerve cells,

also called neurons.

In fact, in order for your neurons to function properly,

all three electrolytes need to be present

in the proper ratios.

And we now know that even slight reductions

in electrolyte concentrations or dehydration of the body

can lead to deficits in cognitive and physical performance.

Element contains a science-backed electrolyte ratio

of 1,000 milligrams, that’s one gram, of sodium,

200 milligrams of potassium,

and 60 milligrams of magnesium.

I typically drink Element first thing in the morning

when I wake up in order to hydrate my body

and make sure I have enough electrolytes.

And while I do any kind of physical training

and after physical training as well,

especially if I’ve been sweating a lot.

If you’d like to try Element, you can go to drinkelement,

that’s lmnt.com slash Huberman,

to claim a free Element sample pack with your purchase.

Again, that’s drinkelement, lmnt.com slash Huberman.

Today’s episode is also brought to us by Thesis.

Thesis makes what are called nootropics,

which means smart drugs.

Now, to be honest, I am not a fan of the term nootropics.

I don’t believe in smart drugs in the sense that

I don’t believe that there’s any one substance

or collection of substances that can make us smarter.

I do believe based on science, however,

that there are particular neural circuits

and brain functions that allow us to be more focused,

more alert, access creativity, be more motivated, et cetera.

That’s just the way that the brain works.

Different neural circuits for different brain states.

Thesis understands this.

And as far as I know, they’re the first nootropics company

to create targeted nootropics for specific outcomes.

I’ve been using Thesis for more than six months now,

and I can confidently say that their nootropics

have been a total game changer.

My go-to formula is the clarity formula,

or sometimes I’ll use their energy formula before training.

To get your own personalized nootropic starter kit,

go online to takethesis.com slash Huberman,

take a three-minute quiz,

and Thesis will send you four different formulas

to try in your first month.

That’s takethesis.com slash Huberman,

and use the code Huberman at checkout

for 10% off your first order.

I’m pleased to announce that the Huberman Lab podcast

is now partnered with Momentus Supplements.

We partnered with Momentus for several important reasons.

First of all, they ship internationally

because we know that many of you are located

outside of the United States.

Second of all, and perhaps most important,

the quality of their supplements is second to none,

both in terms of purity and precision

of the amounts of the ingredients.

Third, we’ve really emphasized supplements

that are single ingredient supplements

and that are supplied in dosages

that allow you to build a supplementation protocol

that’s optimized for cost,

that’s optimized for effectiveness,

and that you can add things and remove things

from your protocol in a way

that’s really systematic and scientific.

If you’d like to see the supplements

that we partner with Momentus on,

you can go to livemomentus.com slash Huberman.

There you’ll see those supplements,

and just keep in mind that we are constantly expanding

the library of supplements available through Momentus

on a regular basis.

Again, that’s livemomentus.com slash Huberman.

Let’s talk about caffeine.

So as I mentioned earlier,

caffeine is consumed by basically most all adults

every single day

and consumed at very regular times each day.

In fact, if you were to take a look at your caffeine intake

or the caffeine intake of somebody close to you,

what you would realize is that they don’t do so well

if their caffeine intake arrives even 10, 20,

or 30 minutes past their expected

or usual intake of caffeine.

That’s pretty remarkable,

and it brings to mind ideas

that we are all quote-unquote addicted to caffeine

or that caffeine is somehow bad.

I’m certainly not going to make the argument

that caffeine is bad.

First of all, I’m a regular caffeine user.

I wouldn’t call myself a caffeine abuser,

but I am a regular caffeine user,

and caffeine is known to have certain health benefits.

I listed off a few of them earlier,

but I’ll mention those again now before going forward.

Caffeine is known to have certain neuroprotective effects,

and that is because of its ability

to increase neuromodulators such as dopamine,

but also other so-called catecholamines like norepinephrine.

If you don’t know what those names mean,

these are molecules that increase levels of alertness,

motivation, and drive,

and so then therefore not surprisingly,

the large-scale analyses

of the relationship between depression and caffeine

shows that provided people are not drinking so much caffeine

that it makes them overly anxious,

that regular intake of caffeine

is inversely related to levels of depression,

so it may have some antidepressant effects,

and those could be direct or indirect.

What do I mean by that?

Well, you can imagine that if people are ingesting caffeine

and they are more motivated to do work

and pursue quality social interactions,

then the probability that they will have depression

could be lower.

It could also be that there are direct effects

on the chemical systems of the brain

that relate to mood and well-being

that could offset depression.

It is not clear whether or not the effects of caffeine

in countering depression are direct or indirect.

Nonetheless, there’s a relationship there,

and it’s an interesting and positive one,

or I should say negative correlation,

positive effect overall on mood and well-being, to be exact.

Now, it’s also the case that caffeine

can improve mental performance and physical performance.

This has been demonstrated in tens of thousands of studies.

I will review a few studies on this in particular today,

but to just give you a sense of how caffeine works

at the level of its timing and impact

on mental performance and physical performance,

when we ingest caffeine,

provided that we don’t have a lot of food in our stomach

and that our blood sugar isn’t particularly high,

generally, we experience an increase in alertness

within about five minutes,

and that increase in focus and alertness

peaks around 30 minutes after ingestion of caffeine

and persists for as long as 60 minutes.

Now, this is assuming that one takes caffeine in pill form

or drinks the entire caffeine drink

within a short period of time,

but a little bit later,

I’ll talk about how you can consume caffeine

at regular intervals while doing mental work

or physical work in a way

that can further increase mental performance

and physical performance.

But let’s just touch on what caffeine intake

really does for mental performance and physical performance.

Perhaps the most robust finding

across all of the studies that I’ve examined

is that caffeine reduces our reaction time.

That is, it improves our reaction time.

It doesn’t make it longer, it makes it shorter.

So for instance, in a laboratory study

where people were asked to hit a lever

every time they hear a tone,

you can greatly reduce the time

between the tone and the pressing of the lever

if people ingest caffeine about 30 minutes

before they do that task.

Now, that seems like a trivial task,

but this is also seen in the domain of sports performance

and even in cognitive performance

where people have to arrive

at a particular answer to a question.

And the answer to that question

has to be pulled from their memory banks

within their brain, their hippocampus, for instance,

a brain structure involved in memory.

And if you are asking people, for instance,

to remember the capitals of different states or cities

or to remember certain historical facts,

they will do that at a particular rate.

But if they’ve ingested caffeine within the hour prior,

their ability to recall that information

is much, much better.

They are faster and it does not appear

that accuracy is reduced.

In fact, in many cases, accuracy is enhanced.

And that’s because caffeine both works

on the reaction time systems of the brain and body.

I’ll talk about the mechanisms for that in a little bit,

but it also stimulates certain neurotransmitters

and so-called neuromodulators within the brain and body

that give the neural circuits in the brain

that are associated with learning and memory

a lower threshold to activation.

That means that we are better able to access

the brain circuitry involved in learning and memory

when we have a certain amount of caffeine

circulating in our system.

So this makes caffeine

an incredible performance-enhancing compound.

And I could give you tens of thousands of examples

of this in humans.

But before I do that, I want to just touch on

what we know about the existence of caffeine in nature

and what the existence of caffeine in nature

and its effects on other animals

tells us about what caffeine does in humans.

Because as I alluded to earlier,

what caffeine is doing for us

is not just making us more alert, improving our memory,

improving our reaction time, and so on.

It’s actually acting as a powerful reinforcer of experience.

And it’s acting as not just a powerful reinforcer

of the caffeine-containing drink that we drink,

but also the mug that it’s contained in,

plus the person that we might be sitting across

from when we consume that caffeine, and so on and so forth.

If it’s a little bit hard for you to conceptualize

what a reinforcer is and why I’m calling it a reinforcer,

let me spell it out in three specific ways.

We often hear about the word reward and we think,

okay, if we do certain things and we like the outcome,

then those certain things are rewarded, right?

If we’re doing something, we receive praise,

the praise is the reward,

and therefore we are more likely

to do that thing in the future.

In fact, a lot of parenting is like that,

and a lot of life is like that.

However, when we hear the word reward,

we often think about something that feels good to us.

And certainly if we’ve worked hard and we get some praise,

that’s natural for the praise to feel good to us.

Or for instance, if we work very hard

and we get a certain outcome, a trophy,

a financial outcome, a degree outcome,

recognition, et cetera, all of those can act as rewards,

but those are all conscious rewards.

We are aware that they are happening.

Reinforcers are a little bit different

because the word reinforcement can apply

to conscious rewards of the sort that I just described,

but there are also many ways in which caffeine

stimulates the release of chemicals in our body

that act as reinforcers,

but those reinforcers are subconscious.

That is, we are not aware that they cause this preference

for the activities that cause their release.

So the study I’m about to describe beautifully,

I believe, encapsulates how is it that humans

came to consume caffeine and why caffeine exists in nature

and the powerful effects of caffeine as a reinforcing agent,

both in animals, insects, and in you and me.

And the title of the paper is

Caffeine in Floral Nectar Enhances

a Pollinator’s Memory of Reward.

Keep in mind that caffeine is made from plants.

Some of you will say, duh,

but I think some of us don’t realize

that the reason why there is caffeine in coffee

is because coffee comes from a plant,

as a coffee bean, certain teas,

which of course are plants that people brew.

Caffeine is contained in those teas, such as yerba mate.

Well, why would this bitter substance,

because in fact,

caffeine is quite bitter in high concentrations,

why would this bitter substance be something that insects

or animals would want to consume at all?

It turns out that in most plants,

caffeine is present in small enough quantities

that insects and other animals,

and in fact, we can’t actually taste the caffeine.

If I were to give you a little bit of pure caffeine,

yes, it would be a stimulant for you,

but you would say that it tasted awful.

It’s in a category of compounds

that would strongly stimulate

the bitter receptors on your tongue,

and would make you cringe and pucker,

and essentially walk away from whatever it is

that contained that caffeine,

and from the experience that contained that caffeine.

Well, in nature,

caffeine is present in very low concentrations,

or is masked by other flavors

within flowers, beans, and plants.

And what this paper really points to

is that caffeine in nature is acting as a reinforcer

for bees that are consuming different nectar.

So the way that it works is that bees, of course,

go from flower to flower,

and they are consuming the nectar.

They are bringing nectar and pollen back to the hive,

and that provides critical nourishment for the bee colony.

The bees are foraging in a way

that includes information about color,

in particular, ultraviolet color,

things that we can’t see, but they can see,

because they have different photoreceptors than we do.

And what this study shows is that plants and nectars

that contain very small amounts of caffeine

are the preferred sources of food for bees.

And the study is beautiful

because they were able to confirm

that they could mask the caffeine taste,

so if they know that the bees

are not preferring the taste of caffeine,

but what they do is they pair caffeine

with different food sources for the bees,

then they remove the caffeine.

And what they find is that the bees

very strongly prefer flavors that contain caffeine,

not because they could taste the caffeine,

but rather for the way that those caffeine-containing

flavors made the bees feel.

So how do those caffeine-containing flavors

make the bees feel?

The same way that they make you and I feel,

a little bit more alert,

and thereby able to do more work.

For the bee, the more work is the consumption of more food,

which then has a further reinforcing effect.

So what we’re really talking about here

is the fact that, A, caffeine exists in nature, in plants.

It exists in concentrations that are very low,

so low, in fact, that they are not detectable

to the taste receptors of insects,

and in many cases to the taste receptors of humans.

And of course, there can be high levels of caffeine

in a plant, but if the plant also contains compounds

that mask the flavor of caffeine,

well, then those plants are going to essentially

be even stronger reinforcers for the flavor of the plant.

Okay, so now we’re talking about strong flavors

plus strong neurostimulant effects of caffeine.

And the most important point here

is that all of these effects of caffeine are subconscious.

It is not because the bee or you likes the taste of caffeine.

In fact, most people,

when they take their first sip of coffee,

they find that it tastes bitter and kind of noxious.

They don’t like it.

You may not even remember that

because it happened so long ago,

and because caffeine is such a strong reinforcer

that very quickly you come to like the taste of coffee.

You might even come to like the feeling

of your mug in your hand.

You might even come to like the smell of coffee,

and so on and so forth.

And that’s because caffeine stimulates the release

of certain neurochemicals in the brain,

in particular, dopamine and acetylcholine,

two neuromodulators that increase our focus and alertness

in our feelings of wellbeing.

A little bit later, I’ll tell you

that caffeine stimulates the release of dopamine

in a way that’s very much distinct

from the classical dopamine pathway

associated with addiction and reward.

In fact, we can think of caffeine

as having a somewhat privileged access

to the reward systems.

I’ll give you a bit of a hint of where this is going.

Caffeine stimulates the release of dopamine

and acetylcholine, not within the classic

so-called mesolimbic reward pathway.

That’s just fancy nerd speak

for the reward pathways of the brain.

They’re associated with things like sex and food

and drugs of abuse like cocaine and methamphetamine,

but rather caffeine seems to stimulate

the release of dopamine in the parts of the brain

that are associated with alertness and cognition,

meaning the forebrain.

This is very important.

We have multiple dopamine systems in the brain and body,

and caffeine seems to stimulate dopamine directly

within the components of the brain

that are associated with clarity of thought and wellbeing,

but more so clarity of thought.

Now, I’m also talking about caffeine as a strong reinforcer

in that it makes you feel good overall, and it does,

and that suggests that it also taps

into the more classic reward pathway,

but it does that in a very interesting

and frankly, almost diabolical way.

When we regularly ingest caffeine,

it stimulates the increase in dopamine receptors

at multiple sites throughout the brain,

but in particular within the reward pathways of the brain.

So not the areas of the brain that are associated

with focus and clarity of thought and cognition.

It does that, but it is also increasing the level

of dopamine receptors in the reward pathway.

And what that means is that for any dopamine

that’s released in response to a positive experience,

social experience, or any number of the other things

that can stimulate dopamine release,

there are more receptors, more parking spots, if you will,

for that dopamine to arrive at and to exert

its increases in mood, increases in motivation,

and overall feelings of drive and excitement.

So there are four ways that caffeine works

that we need to understand.

First of all, caffeine acts as a reinforcing agent.

It increases the probability that you will return to

and engage in a certain activity

or consume a certain beverage or food.

Second of all, caffeine increases dopamine and acetylcholine

which are both neuromodulators in the forebrain,

which helps us improve our ability to think,

to modify our rule sets, that is to adjust our strategies

for different social situations and mental demands

and physical demands.

And third, it increases the number and efficacy

of dopamine receptors in the reward pathways of the brain.

That is, it makes things that would feel pretty good

feel even better.

And fourth, caffeine acts as an antagonist to adenosine,

which offsets the sleepiness that we would otherwise feel

from the accumulation of adenosine that occurs

as we are awake for more and more hours throughout the day.

So let’s talk first about caffeine as a reinforcing agent.

Again, this was first most beautifully demonstrated

in this study on honeybees where the bees prefer nectars

that contain caffeine.

And that all makes perfect sense in terms of the ecology

of bees and flowers that contain nectar.

There’s an advantage, at least in terms of adaptation,

that the flower benefits because of distribution

of things from the flower, which is good for the flowers

and the bees benefit because they’re getting food.

And so there’s a kind of a symbiosis there.

But with humans, we’re consuming caffeine-containing

beverages for our sake.

I don’t think we have it in mind,

nor do the bees have it in mind, frankly,

that we’re trying to preserve the plants

that provide the caffeine.

I think we would all suffer, or I should say 90% of adults

would suffer greatly if all the caffeine-containing

coffee and tea plants were gone, certainly.

But most of us are not consuming coffees and teas

and caffeine-containing foods because we’re thinking

about the plants they come from

and we want to help those plants.

We’re thinking about how we want to help ourselves.

And yet the point of the reinforcing effects of caffeine

are that they are largely subconscious.

We are not aware of them.

Now you might say, no, that’s not true.

When I drink caffeine, it makes me feel really good.

So I’m aware that it makes me feel good.

In order to illustrate how reinforcement really works,

let me give you the counter example,

which would be an aversive agent.

So we have reinforcing agents and we have aversive agents.

Let’s say that there were compounds in nature

that exist in plants that are aversive.

And indeed they are.

And let’s say that these compounds were present

at such low concentrations that you couldn’t taste them.

Let’s say you wake up in the morning

and you go to your refrigerator and you open it up

and you are thirsty.

And so you reach for a nice, you know,

rich red containing beverage in a glass jar.

Maybe it looks like cranberry juice

or something of that sort,

or even a nice clear glass of water.

It looks like a jug of water, a glass of water,

and you drink that.

Tastes fine to you.

Maybe even tastes great to you.

And then let’s say about 30 minutes later,

you feel a little queasy.

You feel a little off.

You feel like going back to sleep.

You just don’t feel very good.

You don’t know why,

but your nervous system is a predictive machine.

And it has a process in which it back integrates,

or I should say integrates backwards

into your immediate experience

that preceded that not so good feeling.

We can reliably say that there is a much lower probability

that the next day when you wake up

that you would reach for that same beverage

or for that same container even.

And maybe if you’re in a novel environment,

maybe you’re staying in an Airbnb or a hotel

or something of that sort,

you might even find that you don’t really like the kitchen

in which you consume that beverage in the first place.

Now, you don’t know why.

And unless you got very, very sick the day before,

it’s unlikely that you would have such a strong response

that you would entirely avoid, for instance,

water or glass jars containing liquids, et cetera.

But let’s say you went back to the refrigerator

and you consumed beverage again,

and you just didn’t feel so well.

You felt less good than you normally would.

Well, even without any ability to taste

what’s in that beverage,

and even without any understanding

of what was happening to you at a conscious level,

there is a very, very high probability

that you will avoid drinking that particular beverage,

and certainly at that location

and in the same volume in the subsequent days.

That’s just the way that aversive agents work.

And they work by way of activating neurons in the gut

that communicate with areas in the brain

that give us this feeling of queasiness.

And for some of you hearing this,

that pathway and that association

with times in which you felt queasy

and as if you wanted to vomit is so powerful

that you might even be feeling

some of that symptomology now.

For certain people, that’s going to be increased salivation,

which precedes vomiting.

We know that there’s a class of neurons in the brain

related to an area called area post-tremor

that actually stimulates vomiting.

And if I keep talking about this,

I’ll probably feel like I want to vomit.

So I’m going to move on from this in a moment.

So when we ingest caffeine containing beverages and foods,

it’s the exact opposite scenarios to what I just described.

Caffeine as a reinforcer makes us feel slightly better

or a lot better in the immediate minutes

and hours after we ingest it.

So it’s acting as a reinforcing agent,

not just while you’re under the effects of caffeine,

but for the things that preceded

the ingestion of caffeine,

which is why you return again and again

to caffeine containing beverages,

such as coffee and tea,

or maybe even foods that contain caffeine,

even if the taste of those foods is not something

that you would otherwise consider especially delicious.

In fact, most people,

when they take their first sip of coffee or tea

or other caffeine containing beverage,

they find it to be very bitter.

And that’s not because of the taste of caffeine,

it’s because of the taste of the beverage itself,

independent of caffeine.

However, when caffeine is present in there,

they come to prefer that taste over most all tastes.

In fact, they will, as I mentioned earlier,

will invest a lot of financial resources

and time and energy to make sure

that they get that beverage.

What they’re trying to make sure

is not that they get that taste,

but that they get the caffeine.

It is that positively reinforcing.

And the taste therefore takes on new significance,

new meaning, and we come to associate it as positive.

And in fact, most of us, including myself,

love the taste of espresso, love the taste of coffee,

love the taste of yerba mate,

even if the initial taste,

the very first time that we consumed that beverage

was either neutral or negative.

And that is all because of the reinforcing properties

of caffeine.

And then of course,

there are the more direct actions of caffeine,

that is the faster actions of caffeine.

And just to list those off again, very briefly,

so that you have them in mind going forward,

caffeine also increases the release of dopamine

and acetylcholine,

both of which are neuromodulators in the forebrain,

which increases clarity of thought

and your ability to rule switch,

your ability to move from one context to another

and change and understand the rules of engagement,

social engagement, physical engagement,

mental engagement, and so forth.

And as I mentioned before,

caffeine also increases the number of dopamine receptors

in the reward pathway,

such that any good thing that happens to you,

any positive experience that you have

will have a more potent effect

on your feelings of wellbeing.

And last but certainly not least,

caffeine acts as an adenosine antagonist.

It reduces your feelings of lethargy and fatigue

and your desire to sleep

by parking in the receptors for adenosine

and not allowing adenosine to have its pro-sleepy,

if you will, effects on your brain and body.

I’d like to take a quick break

and acknowledge one of our sponsors, Athletic Greens.

Athletic Greens, now called AG1,

is a vitamin mineral probiotic drink

that covers all of your foundational nutritional needs.

I’ve been taking Athletic Greens since 2012,

so I’m delighted that they’re sponsoring the podcast.

The reason I started taking Athletic Greens

and the reason I still take Athletic Greens

once or usually twice a day

is that it gets me the probiotics that I need for gut health.

Our gut is very important.

It’s populated by gut microbiota

that communicate with the brain, the immune system,

and basically all the biological systems of our body

to strongly impact our immediate and long-term health.

And those probiotics in Athletic Greens

are optimal and vital for microbiotic health.

In addition, Athletic Greens contains a number of adaptogens,

vitamins, and minerals that make sure

that all of my foundational nutritional needs are met,

and it tastes great.

If you’d like to try Athletic Greens,

you can go to athleticgreens.com slash Huberman,

and they’ll give you five free travel packs

that make it really easy to mix up Athletic Greens

while you’re on the road, in the car, on the plane, et cetera,

and they’ll give you a year’s supply of vitamin D3K2.

Again, that’s athleticgreens.com slash Huberman

to get the five free travel packs

and the year’s supply of vitamin D3K2.

I’d like to just briefly talk about adenosine

and some of its molecular features.

And again, if you don’t have a background in biology,

don’t worry, I promise to make this very clear to everyone.

First of all, caffeine is what’s called a methylxanthine.

It’s a plant alkaloid.

That’s why caffeine itself is very bitter.

Again, if I were to give you

just the tiniest little bit of pure caffeine,

you would find it to be extremely aversive.

And so these plants that have snuck

small enough amounts of caffeine into them,

or that have masked the flavor of caffeine

with other flavors such that bees and humans

want to consume them,

while we don’t know what plants think,

it does seem very diabolical and very clever

in that we are seeking out these caffeine-containing

plants, beverages, and foods,

even though caffeine itself is this alkaloid

that’s very, very bitter.

Methylxanthine, that is caffeine,

binds to adenosine receptors,

and there are really two types of adenosine receptors.

There are these so-called A1 receptors

and the A2 receptors,

and they’re present in different parts of the brain and body

at different levels.

We don’t have to get too far into receptor subtypes.

More importantly to understand

is that adenosine makes us feel tired

because of the way that it taps into the ATP pathway.

The ATP pathway is central to energy production

and feelings of overall energy in our brain and body

in all cells and organ systems.

When caffeine binds to adenosine receptors,

it prevents adenosine from breaking down

certain components of the energy production pathway.

And the net consequence of that is increased cyclic AMP.

So basically, when we ingest caffeine,

we are biasing our system towards the pro-energetic aspects

of these cellular pathways.

Now, it’s really important to understand that in biology,

even if you block a receptor

or you prevent the activity of an enzyme,

and at least in this case,

you end up with more cyclic AMP, more energy,

you’re not really getting more energy.

You’re actually borrowing energy against an overall system

that is frankly non-negotiable.

What do I mean by that?

Well, let’s say that you were to wake up

after six or eight hours of sleep

and to drink a lot of caffeine

and keep drinking caffeine throughout the day,

throughout the day, blocking those adenosine receptors.

Yes, you’ll offset fatigue.

You’ll offset sleepiness

because that adenosine simply can’t function.

But at the point where the caffeine becomes dislodged

from the adenosine receptors,

you will have a massive glut, a backlog of adenosine,

and you will feel extra, extra sleepy.

So really there’s no way to create more energy

in your system.

Really what you’re doing is you’re changing the timing

in which the sleepy signals

and the more energetic signals are arriving.

And this is really important to understand as the backdrop

to the various tools that we’re going to get into next,

in which you can use caffeine

for enhancing mental performance and physical performance

and other aspects of health.

But it’s very important to understand this concept

that when you wake up in the morning,

provided that you slept well and enough the night before,

your levels of adenosine will be about as low

as they will ever be.

Actually, in order to get your adenosine levels

really bottomed out,

you want to avoid caffeine

in the first 90 to 120 minutes after waking.

We’ll talk about why that is because it turns out

there’s a way to completely clear adenosine

out of your system in the hour or so after waking.

But for most people,

adenosine levels are going to be close to their lowest

after a good night’s sleep.

But there’s really no negotiating the accumulation

of adenosine that’s going to occur

and going to bias you towards feeling more sleepy

than you would otherwise

that’s going to occur throughout the day.

There’s really no way to eliminate adenosine.

All you can really do is block its function.

So it’s sort of like borrowing energy

against the fatigue that you will inevitably feel.

Now, this actually has

a very important socioeconomical relevance.

Before caffeine was regularly consumed by human beings,

we were really slaves to the light-dark cycle.

And this was especially true

before the presence of artificial lighting.

But even before the advent of artificial lighting,

humans were largely constrained

to the outside light-dark cycle.

We need to be active during the day

and working during the day,

and we need to be asleep at night.

Caffeine allows us to divorce ourselves

from that circadian cycle.

Circadian just means about 24 hour.

Caffeine allows us to do that at least somewhat

by way of increasing our alertness,

that is spiking our alertness

at various times throughout the day and even at night.

This is how we can have shift workers, for instance,

that can sleep during the day

and then drink a strong cup of coffee at 8 p.m.

and then work into the night.

That ability completely transformed our society.

Now, of course, the healthiest schedule,

we know this with certainty,

the healthiest schedule for brain and body

is going to be to be alert during the daytime

and asleep at night.

There’s no question about that.

Shift workers run into all sorts of health problems.

And thank you, shift workers,

for doing the important work that you do.

We need you, air traffic controllers, paramedics,

firefighters, police officers, et cetera.

But we know that there are serious health consequences,

negative health consequences, that is, for shift workers.

But for most people out there,

about 95% of people follow a typical schedule

where they’re awake during the day and asleep at night.

And yet it used to be

before the advent of caffeine-containing beverages

that if you were sleepy in the afternoon,

you either had to take a nap or battle that sleepiness.

That your activity rhythms and your sleep rhythms

were governed by these circadian changes

in availability of sunlight and when you slept.

And you just didn’t have the ability to ingest a beverage

that would increase your levels of alertness

because you block adenosine.

So this is important to understand that nowadays,

we certainly live in a time

in which we use, in fact, 90% or more of adults

and half or more of adolescents and teenagers

use caffeine as a way to negotiate with,

to borrow against this natural pattern of adenosine

making us sleepy.

But again, you’re just offsetting the effects

of sleepiness that adenosine causes.

You can’t eliminate the adenosine entirely.

The important point is that adenosine

as a pro-sleepy molecule

is a non-negotiable aspect of your biology.

In fact, it’s so non-negotiable that every 24 hours

you are going to release adenosine

and you’re going to release adenosine

in direct proportion to how long you’ve been awake.

So the longer you’ve been awake,

the more adenosine circulating in your system.

There are really only a handful of ways

to completely clear out adenosine.

The major one being to get sleep.

The other is to take a short nap, which of course is sleep,

but it’s shallow sleep or non-sleep deep rest,

so-called NSDR has been shown to reduce levels

of adenosine.

And there are certain things such as

viewing morning sunlight,

which because of its effects on cortisol

can quote unquote clear out adenosine.

We’ll talk about this in more detail in a few minutes.

And there’s also evidence that certain forms of exercise

provided that it’s brief and intense

can also reduce adenosine, not just block its effects.

Now that we’ve talked about some of the incredible mechanisms

by which caffeine changes our experience of life,

increases alertness and mood, et cetera,

I want to talk about the use of caffeine as a tool.

Now, caffeine is a very potent and useful tool

for enhancing mental health,

physical health and performance,

but there are certain considerations

one has to keep in mind, in particular dose.

Now, first off, not everybody will respond

to the same dose of caffeine the same way,

but we can reliably say that your body weight

is a good measure by which you can estimate

what a healthy, useful dose of caffeine would be.

So for most people,

ingesting one to three milligrams of caffeine

per kilogram of body weight

is going to be the range in which

caffeine can have positive effects

without making us feel overly anxious

and give us that feeling that

we’re jumping out of our skin

and turn the otherwise positive experience of caffeine

into an aversive one.

For those of you that aren’t familiar

with thinking in terms of kilograms

and normally thinking pounds,

I’ll just quickly give you some general estimations

that for instance, 100 kilograms equals 220 pounds.

So for me, I weigh 100 kilograms.

That means that one to three milligrams,

again, milligrams, thousandths of a gram,

one to three milligrams of caffeine

per kilogram of body weight would mean for me,

I could safely ingest 100 to 300 milligrams of caffeine

in a single dose, in a single drink,

if that’s the way I’m consuming it,

or pill form if that’s the way that I’m consuming it.

And it’s very likely that that will be a tolerable dose.

However, if you are not somebody

that’s accustomed to drinking caffeine on a regular basis,

I suggest you start on the lower end

of that one to three milligrams per kilogram

of body weight range.

So for instance, if you’re somebody who weighs 50 kilograms,

that’s approximately 110 pounds,

and you would be pretty comfortable ingesting somewhere

between 50 and 150 milligrams of caffeine.

So what I recommend is that people

who are considering using caffeine as a tool,

or who are already ingesting caffeine,

start to think about the dosage of caffeine

that you are ingesting or plan to ingest,

and the timing in which you ingest that caffeine

relative to certain tasks throughout your day,

you’re waking and you’re sleeping.

We’ll talk about that in just a moment.

But the first step for you is to figure out

how much you weigh in kilograms,

and then to go to that number of one to three milligrams

of caffeine per kilogram of body weight.

And that’s a good range in which you might want

to explore the use of caffeine in a single application,

meaning a single dose.

Now, I do realize that some people out there

are drinking coffee all day long

or having coffee in the morning,

and then again in the afternoon.

What I’m referring to here is the ingestion of caffeine

in a single bout, right?

One cup of coffee or two cups of coffee, for instance,

to achieve that 100 to 300 milligram range,

if that’s what’s appropriate for your body weight.

But to avoid any confusion,

when I talk about dosage of caffeine,

what I’m really talking about

is not the total amount of caffeine ingested per day.

I’m talking about the total amount of caffeine

ingested in one sitting or setting, that is.

And if you’re somebody who’s drinking caffeine

multiple times throughout the day,

you could imagine, for instance,

let’s say the appropriate dose for you

in order to get an enhancement in mental performance

or physical performance is 200 milligrams,

and you are somebody who’s doing some work in the morning

and you want to have that lift in the morning

to be able to focus better,

and you’re doing some physical exercise in the afternoon

or vice versa, that you would ingest 200 milligrams

of caffeine at two separate times per day,

separated by about four hours.

Now, you don’t have to separate them.

You could put them two hours apart, for instance,

but we’ll talk about half-life of caffeine and so forth.

Just keep in mind that if you’re ingesting

200 milligrams of caffeine

and that’s the appropriate dose for you

based on your body weight,

and then you are ingesting

another 200 milligrams of caffeine an hour later,

you are effectively ingesting

approximately 400 milligrams of caffeine,

which is going to start exceeding the dose

in which you can normally tolerate

without feeling anxious and jittery.

With all of that said,

there is a range of tolerance for caffeine

that’s based on two things.

One is a preexisting disposition,

that is whether or not your genetics and nervous system

and the backdrop of your life,

how much stress you’re experiencing,

tends to make you feel more anxious and alert and jittery

before you ingest any caffeine.

And the other is how so-called caffeine adapted you are.

We often hear about tolerance.

Tolerance means something very specific.

It’s the ability to ingest more and more of something

with a plateau that is a no increase

or an actual reduction in the effectiveness of that thing.

But here we’re not really talking

about tolerance to caffeine.

What we’re talking about is being caffeine adapted.

A simple way to understand

whether or not you’re caffeine adapted or not

is that if you drink caffeine

and it tends to increase your heart rate

and make you feel more alert and a bit more anxious,

then chances are you are not caffeine adapted,

provided the amount of caffeine

is within the healthy range for you, that is,

the ranges we talked about a moment ago.

However, if you’re somebody who drinks caffeine

and you actually feel alert and relaxed,

chances are you are caffeine adapted.

At various times during today’s episode,

I’ll talk about people who are caffeine adapted

and people who are not caffeine adapted.

We’ll talk about the use of caffeine every other day.

I know a few habitual caffeine drinkers, including myself,

just the simple mention of that probably sounds aversive,

but there is actually great utility

to using caffeine every other day as opposed to every day.

But just keep in mind that some people will drink caffeine

and not get much of a lift from it at all.

Other people will drink caffeine

and they will feel extremely anxious,

even at dosages far lower than that one to three milligrams

per kilogram of body weight range

that I described a moment ago.

So you have to take into account individual differences.

That said, one to three milligrams of caffeine

per kilogram of body weight for a given sitting,

you know, for your morning coffee

or your morning yerba mate tea,

is a good range from which to start.

And I do encourage you to go online

and look up the various beverages and foods

that you might be eating that contain caffeine

For instance, some people are surprised to discover

that the coffee that they get

from some of the more standard popular vendors out there,

the small coffee or the medium coffee, for instance,

can contain as much as 400 to 600 milligrams of caffeine.

And that the large coffee that is often sold

at those commercial vendors can contain

as much as one gram, 1,000 milligrams of caffeine.

Now, you may be adapted to that

such that it doesn’t make you feel anxious,

but if you wonder why you feel irritable

and you get a headache when you don’t get that caffeine

or that amount of caffeine at precisely the time

that you’re used to getting it each day,

that’s because you are consuming quite large quantities

of caffeine on a regular basis.

So I do recommend whether or not you drink soda

or coffee or tea, that you figure out the source of that.

Okay, so figure out what vendor you purchase it from,

what kind of coffee, and go online

and spend a little bit of time

because the information is out there

to discover what levels of caffeine you’re actually ingesting.

Now, if you happen to be ingesting

more than one to three milligrams per kilogram

of body weight of caffeine, that’s not necessarily bad.

However, you do want to be careful

about ingesting very high levels of caffeine

over long periods of time in your life

because there can be issues that start to arise,

in particular, a bias towards higher levels of anxiety

and depletion of certain electrolytes

because caffeine is a diuretic,

can cause you to lose sodium

and other things of that sort.

And also just from simply a dependent standpoint,

it does appear that if you ingest high levels of caffeine,

that is exceeding the dosages

that normally you could get away with

and get just as much mental enhancing

and physical enhancing benefits,

that you can cause some disruption to the microvasculature,

you can bias yourself towards headaches, anxiety attacks,

and you can become actually quite irritable

when you’re not getting those higher levels of caffeine.

So I do encourage you to figure out

not just what an appropriate caffeine dosage

would be for you,

but also how much caffeine you might already be ingesting.

The first tool I’d like to talk about

is one that I’ve mentioned before

on this podcast several times.

And it’s something that if you haven’t heard of,

will be very useful to you.

And if you have heard this tool before,

I’m going to add some additional features

to the description of this tool

that should make this worthwhile for you as well.

And that is to delay your caffeine intake

to 90 to 120 minutes after waking up on most days.

And I’ll be very clear as to days

in which you might want to ingest caffeine

more closely to when you wake up.

Why would you want to delay your caffeine intake

to 90 to 120 minutes after waking?

The answer to that is very simple.

Many people wake up in the morning,

they drink caffeine within 10, 20, 30,

sometimes within two minutes of waking,

and they feel more alert.

Naturally, that makes sense

because of the effects of caffeine

in blocking the effects of adenosine

that I talked about earlier,

and its effects on other neurotransmitter systems.

But then what they find is that in the early afternoon,

in particular after lunch,

they experience a dramatic dip

in their overall levels of energy,

the so-called afternoon crash.

And in most cases, the way they respond to that

is to ingest more caffeine,

which indeed can increase their levels

of mood and alertness.

However, as we’ll soon talk about,

there is a problem with ingesting caffeine

in the afternoon.

If it falls within eight or 10,

or dare I even say 12 hours of going to sleep,

and that is the caffeine ingested in the afternoon

for most everybody,

I’d say for 95 plus percent of people,

disrupts the architecture and quality

of their nighttime sleep.

And I should say that it doesn’t necessarily

impact their ability to fall asleep,

and maybe even sleep through the night,

but that the depth and quality of that sleep

is disrupted by consuming caffeine in the afternoon.

A little bit later, I’ll talk about

how you can offset some of those negative effects

if you absolutely require caffeine in the afternoon.

But there’s a huge advantage

to restricting your caffeine intake

to the early part of your day,

but not consuming caffeine

within the first 90 to 120 minutes after waking.

In fact, many people find that

if they delay their caffeine intake

to 90 to 120 minutes after waking up,

that they feel more alert in the morning,

and they completely avoid that afternoon crash.

Now that said, many people, including myself,

do need a short nap, or non-sleep deep rest,

or other form of relaxation

for 10 to 30 minutes in the afternoon.

That is natural and healthy.

I’m not referring to the need for that

when I refer to the so-called afternoon crash.

What I’m talking about in the afternoon crash

is a inability to recover energy and focus,

and a need to consume more caffeine

just to make it through the afternoon.

By delaying caffeine intake to 90 to 120 minutes

after waking, there are a couple of things

that are accomplished.

First of all, you offset that afternoon crash,

and this is an effect that many people experience

the very first time they start delaying their caffeine

intake to 90 to 120 minutes after waking.

And the reason this works so well is the following.

As I mentioned earlier, adenosine is a molecule

that builds up the longer that we are awake.

It is a molecule that is reduced

or cleared from our system by sleep.

So when we emerge from sleep,

regardless of how long we’ve slept,

our adenosine levels are lower than they were

when we went to sleep the previous night.

If you slept well enough and long enough,

those adenosine levels can be very, very low,

but they are never completely zero.

When you wake up in the morning,

even if you’re one of these people that springs out of bed

and is ready to attack the day,

and here I’m certainly not describing myself,

I’m not one of those people.

I tend to wake fairly slowly.

But if you’re one of those spring up and attack the day,

or you’re one of the people who moves more slowly

into your day, regardless,

there’s still some residual adenosine in your system.

And this is particularly the case

if you did not get enough sleep

or enough depth of sleep the night before,

the correct ratios of slow wave sleep

and rapid eye movement sleep.

And for those of you interested in optimizing sleep,

I’ll just refer you to our Master Your Sleep episode

of the Huberman Lab Podcast,

the Perfect Your Sleep episode of the Huberman Lab Podcast.

And we have a toolkit for sleep,

all of which are available zero cost,

timestamped, et cetera, at hubermanlab.com.

You wake up in the morning

and your adenosine levels are low, but they’re not zero.

And if you didn’t sleep that well

or deeply enough the night before,

you’re going to have more adenosine in your system.

You might think the logical thing to do

is therefore to drink caffeine

and to block the adenosine that’s there.

But what happens if you do that is there’s an accumulation,

a sort of glut of adenosine that hangs around.

And then in the afternoon,

when the effects of that caffeine start to wear off,

you will experience the so-called afternoon crash.

As I mentioned earlier, there is a way to clear out

the adenosine that’s present

when you wake up in the morning

and to clear it out essentially completely

without just blocking its receptors

and letting it accumulate or hang around.

And the way to do that

is to deliberately spike your cortisol.

Now, many of you have heard of cortisol,

the so-called stress hormone, as a bad thing.

And indeed, chronically elevated cortisol is a bad thing.

It depletes your immune system.

It’s bad for psychosocial effects.

It tends to make us feel anxious and on and on.

But cortisol itself is not bad.

Cortisol is wonderful.

Cortisol enhances the efficiency of the immune system.

It makes us alert and focused.

It stimulates our metabolism.

It does a huge number of positive things

provided that it is released in a circadian fashion,

that is at the appropriate times every 24 hours,

and that it tends to peak very close to waking.

In fact, one of the reasons you wake up in the morning,

assuming that you weren’t woken up by some noise

or sleeping in an environment that’s too warm, et cetera,

is that your cortisol levels start to rise.

And shortly after waking,

your cortisol levels will start to reach their peak.

And when I refer to a cortisol pulse,

that’s just biology nerd speak

for a rise and peak in cortisol.

You want that cortisol pulse to occur early in the day,

close to waking.

And you want that for a couple of reasons.

First of all,

if you don’t restrict that cortisol pulse

to early in the day,

it will tend to bleed into the later parts of the day.

And actually a late shifted cortisol peak

is one of the hallmark signatures of depression,

low-level depression and serious depression.

And it can start to disrupt sleep

and certainly can disrupt mood metabolism

and your immune system.

So you want that cortisol peak early in the day.

How do you ensure that that happens?

Well, you wake up in the morning

and whether or not you’re a bounce out of bed type

or you’re a more groggy,

you know, kind of wade slowly into the day type like I am,

you wake up and you don’t ingest caffeine.

Fine and in fact,

beneficial to hydrate with water and electrolytes.

Terrific, in fact,

I would say necessary to get bright light in your eyes,

ideally from sunlight.

I’ve talked about this many, many times

before on the podcast.

If you wake up before the sun comes out,

then turn on bright artificial lights.

But then certainly once the sun is out

and even on cloudy days,

in fact, especially on cloudy days,

get outside for anywhere from five to 20,

maybe even 30 minutes,

do some work outside,

take your breakfast outside.

If you’re a breakfast eater,

get something done outside,

even if it’s just to get outside

and get bright light in your eyes.

Why?

Well, because it’s been shown in studies on humans

that getting bright light in your eyes

in the first hour after waking

or as soon as possible after waking

increases the peak of that cortisol pulse by 50%, five, zero.

And that cortisol pulse,

yes, increases mood,

yes, increases alertness,

but it does one other very important thing,

which is that through an indirect pathway,

it can clear out any residual adenosine

that might be present in your system

when you wake up in the morning.

Again, this is going to be especially important

for those of you that are not getting as much sleep

or as much quality sleep as you would like.

It’s going to be very important for you

to get that morning bright light, ideally from sunlight,

get that cortisol peak going.

Other ways to increase that cortisol peak

would be to do some physical activity.

If you don’t have time to do a full workout,

well then getting some movement,

10 minutes of skipping rope

or even five minutes of skipping rope

or jumping jacks or walking,

if that’s all you have time for,

ideally while getting the sunlight in your eyes,

but that’s going to zero out

the adenosine present in your system.

If however, you were to wake up

and immediately drink caffeine,

caffeine itself can stimulate the release of cortisol

a little bit more than it would otherwise

be present in your system.

But by blocking those adenosine receptors

and because of the indirect effects of caffeine

on the cortisol system,

you actually are reducing the clearance of adenosine

that would otherwise occur.

So I realize that’s a mouthful, just to be very clear.

If you wake up and you ingest caffeine right away,

you’re blocking the adenosine receptor,

but you’re not clearing it out.

You’re also preventing cortisol

from having its normal increase in rise

such that it can directly clear out adenosine

because cortisol can clear out adenosine.

And that’s what you want.

You want to be at maximum alertness and focus

in your morning and throughout your day.

And by delaying your caffeine to 90 to 120 minutes

after waking, you set up your system

so that you get that morning cortisol peak,

ideally a peak that’s even greater

because you’re getting your bright light viewing.

And then when you ingest your caffeine

90 to 120 minutes after waking,

not only will you be craving it just a little bit,

but you will be drinking that caffeine

on an already existing backdrop of increased alertness

for two reasons.

One is adenosine is zeroed out

and your cortisol peak is higher.

And so now when you ingest caffeine,

you can actually ingest levels of caffeine

that are a little more reasonable

that almost with certainty are going to fall

in this one to three milligrams per kilogram dosage

and will allow you to feel really alert

and will carry that alertness well into the afternoon hours

without the need to drink more caffeine

and thereby will prevent you from drinking caffeine

and disrupting your nighttime sleep.

And of course, by getting better nighttime sleep,

you’re going to zero out your adenosine even more.

So what I’m describing here are essentially two tools.

I’m telling you to get morning sunlight

and maybe some exercise in conjunction with that,

even if it’s brief exercise.

But the main tool of delaying caffeine 90 to 120 minutes

after waking has immediate effects,

but it also sets in motion a cascade or domino falls

that lead to better sleep and more wakefulness

the next night and the next day and so on and so forth.

Now, I realize there are some people

who just simply cannot or will not delay their caffeine

90 to 120 minutes after waking for whatever reason.

First off, let me say that if you are somebody

who likes to wake up and do very intense exercise

within the first 90 minutes after waking,

well, in that case, it would be appropriate

to ingest your caffeine just prior to doing that exercise.

Not a problem, not a problem,

but you should expect that the combination

of drinking caffeine very shortly after waking

plus exercising very intensely shortly after waking

will increase the intensity of that early afternoon

and afternoon fatigue that you feel.

Now, for some people, that’s a great thing.

They can afford to take a nap or do non-sleep depressed,

step away from work and so forth.

In that case, I strongly encourage you to do whatever it is

that allows you to get regular exercise

because regular exercise is going to be very beneficial.

In fact, we did an entire episode

called Toolkit for Fitness that describes

a couple of different, but really one main structure

that allows you to get the appropriate amount

of resistance training and cardiovascular training

and flexibility training throughout the week.

I happen to follow that program and it works very well

and it does involve some of those workouts

to come very early in the morning, shortly after waking,

and in those cases, I do ingest caffeine just prior to those

so within 10, 20 minutes of waking.

However, on other days, I personally delay my caffeine

intake 90 to 120 minutes and I’ve done that to great benefit

and most people, if not all people that try that

have reported the same.

I should mention that some people will find getting out

to that 90 minutes to be excruciatingly difficult

because they’re so accustomed to ingesting caffeine

close to waking up, in that case,

maybe just push out your caffeine intake

by about 15 minutes each day

until you hit that 90 to 120 minute mark

and that will make it much easier.

It might take you a week or so to get there,

but once you get there,

you’ll find it to be quite easy to maintain.

The other thing is that if you are somebody

who insists on drinking caffeine very shortly after waking,

I would encourage you to drink half of your caffeine then

and then the other half of your caffeine

about an hour later.

That also will help offset some of the afternoon crash

for reasons related to the so-called kinetics of caffeine.

Caffeine has a quarter life of about 12 hours.

That means that if you were to ingest a cup of coffee

at let’s say 8 a.m. and let’s say 100 milligram coffee

just for sake of simplicity,

that about 25% of that caffeine action,

we wouldn’t really say 25 milligrams,

but about 25% of that caffeine action

will still be present at 8 p.m. that night,

which is pretty remarkable.

So there’s a long arc of caffeine effects

and this is why it can impede sleep

if we take caffeine in the afternoon.

But again, if you’re somebody who wakes up

and you really need caffeine right away

and you refuse to do this 90 to 120 minute delay thing

that I’m talking about,

well then in that case,

I would drink half of your caffeine upon waking

and then a little bit more or the other half

about an hour later.

And that will extend the arc of that caffeine effects

such that you don’t need it again in the afternoon

because you won’t experience the afternoon crash.

Because of the way caffeine works,

I should mention that if you ingest caffeine

on an empty stomach,

it will have a more potent stimulant effect

that will also tend to increase the level of jitteriness

that caffeine can produce.

Later, I’ll talk about ways to offset that jitteriness,

but I’ll just tell you one tool now.

Many people opt to take 100 milligrams of theanine,

T-H-E-A-N-I-N-E, theanine,

as a way to offset some of that jitteriness.

Theanine will reduce the jitteriness of caffeine,

which is why many energy drink manufacturers

and even some coffee manufacturers

are now putting theanine in energy drinks

and in ground coffee because, no surprise,

it allows people to consume more of that beverage

and thereby purchase more of that beverage,

which is what these vendors want,

without feeling overly anxious and jittery.

So you can take Pilform theanine

if you want with your caffeine.

I don’t tend to do that.

Rather, I control the total dosage of my caffeine.

I do tend to consume caffeine on an empty stomach

because I do restrict my caffeine intake

to the early part of the day.

And I generally eat my first meal somewhere around 11 a.m.

And then I generally eat my last meal

sometime around 8 p.m. or so.

Those are averages.

I would say plus or minus an hour.

And that’s not because I’m religiously following

any kind of time-restricted feeding.

It’s just that tends to work best

with my schedule and my appetite.

But again, that’s a general theme.

There are days in which I wake up and I’m very hungry

and I might ingest something, a small snack or something,

or if I’m meeting somebody for breakfast,

sometimes I’ll have breakfast, sometimes I won’t,

and so on and so forth.

The point is that you can get away

with drinking less caffeine to get the stimulant effect

if you do it on an empty stomach.

And if you’re somebody who likes to exercise

on an empty stomach, and I’m one of those people,

well, then ingesting caffeine just prior to exercise

can be a fantastic tool.

A little bit later, we’ll talk about some of the

physical performance-enhancing effects of caffeine,

but I’ll just briefly jump to a point about that

as we relate to morning exercise.

If you are somebody who regularly ingests caffeine,

and we can define regularly by

if you’ve ingested caffeine every day

for the last two weeks,

you’re a regular consumer of caffeine,

whereas if you’re somebody who only ingests caffeine

somewhere between two and four times per week,

well, then you are not a regular consumer of caffeine,

you’re an intermittent user of caffeine.

Well, if you’re somebody who’s a regular user of caffeine,

the performance-enhancing effects of caffeine

are going to be most dramatic

if you take two or three days off from drinking caffeine,

which to my mind, I don’t want to call myself a caffeine addict

but a regular caffeine user, that’s a horrible notion to me,

it’s an aversive notion

because I do like the effects of caffeine so much,

but if you really want to see the maximum performance

enhancing effects of caffeine,

you will do either one of two things,

you will either abstain from caffeine for a few days

or three days prior to ingesting caffeine,

or you will use caffeine on an empty stomach.

It’s very clear that caffeine on an empty stomach

enhances both the mental and physical

enhancing effects of caffeine.

And of course, all of that has to be stated

on the backdrop of consideration

that if you’re very, very hungry,

it can make it hard to concentrate and so on and so forth,

so I’m not encouraging people to starve themselves

by any means, certainly don’t do that,

but if you want to maximize

the performance-enhancing effects of caffeine,

you will consume it on an empty stomach.

And then as a final point to that, caffeine is a diuretic,

it causes us to lose fluid and along with that fluid

to excrete sodium because of the effects of caffeine

on various processes within the kidney.

So one thing that works very well

to maintain mood and alertness longer

given a certain amount of caffeine intake

and to avoid the jitteriness

and what can sometimes feel like a crash

or low blood sugar feeling or even blurry vision

is to make sure that you consume

at least an equal volume of water with your caffeine.

And ideally that water would contain

maybe a small pinch of salt

or some sort of electrolyte drink or powder rather.

For me, I use Element, full disclosure,

they are a podcast affiliate and sponsor,

but you don’t need to do that.

You could simply just have a glass of water

alongside your coffee or espresso or your yerba mate

and just put a small pinch of sea salt in that

or even just plain table salt.

And that will help offset

some of the jitteriness of caffeine.

A lot of people think that when they ingest caffeine,

they get the jitteriness and crash

because their blood sugar is low.

And while that can be the case,

oftentimes it’s simply because of the excretion of sodium

that’s occurred when they’ve ingested caffeine.

So I encourage you to hydrate well

and to hydrate with something

that contains a little bit of sodium,

obviously not so much that increases hypertension

or something of that sort,

but a small amount of sodium

or an electrolyte drink like Element.

And there are other electrolyte drinks out there

that can accomplish the same, of course.

Just a couple of quick notes about theanine

because there are a growing number of products out there

that contain theanine.

And there’s certainly a growing number of people out there

who are using theanine for the effect

that I described before,

which is to offset some of the jitteriness

associated with caffeine-containing beverages or foods.

And of course, I should mention

that I’ve talked about the effects of theanine on sleep.

At that sleep toolkit that you can find as a free download,

you don’t even have to sign up for anything.

You can just download it from hubermanlab.com,

go to the menu, go to newsletter,

you’ll see the toolkit for sleep.

You’ll see that the so-called sleep stack

that I use and recommend includes magnesium threonate,

something called apigenin and theanine.

Although that sleep stack is designed to be taken

30 to 60 minutes prior to sleep.

And I make the point there, and I’ll make it again here,

that ingesting theanine prior to sleep is not a good idea

if you are somebody who tends to have very vivid dreams,

night terrors or sleepwalking, excuse me, et cetera.

In that case, eliminate theanine from the sleep stack.

However, a number of people are using theanine

and products are using theanine to offset jitteriness

from caffeine-containing products during the daytime,

daytime consumption that is.

A couple of notes about theanine.

Theanine is something that is present in green tea, right?

It’s now been created as a supplement.

It’s what’s called a non-protein amino acid.

So while there are amino acids and proteins,

there are of course amino acids and non-proteins

and theanine is one such non-protein amino acid.

Theanine tends to stimulate the so-called glutamate

and glutamine pathway.

It’s actually very similar to glutamate and glutamine.

And it has a lot of effects on a lot of different aspects

of the nervous system.

But the general effect of theanine is to compete

for the receptors for certain neurotransmitters.

And the neurotransmitters I’m referring to

are all excitatory neurotransmitters, things like glutamate.

And they govern a tremendous amount of our daily thinking

and action and feeling, et cetera,

because they’re present at so many connections

between neurons in the brain.

Theanine competes for the receptors for glutamate

and tends to reduce our overall levels of alertness.

So really when people take theanine along with caffeine,

what they’re doing is they’re really taking a slight,

I don’t want to call it depressant

to the point where it misleads people

and makes people think that it will make you depressed.

The word is a little bit misleading,

but tends to reduce or blunt some of the more excitatory

pro-alertness actions of neurons in the brain.

So when you take it alongside caffeine,

tends to quote unquote, even things out a bit.

I should mention that the dosages of theanine

that are effective for offsetting the jitteriness

of caffeine is 200 to 400 milligrams.

And the studies that I was able to find showed

that essentially up to 900 milligrams per day can be safe,

but that’s a very high dosage of theanine.

In fact, so much so that it might increase sleepiness

to the point where it wouldn’t feel good.

There are also some positive effects

of daytime consumption of theanine that are independent

of reducing the jitteriness of caffeine.

For instance, there’s a study demonstrating

that 17 days of ingesting theanine

at this 200 to 400 milligram dosage

of at one to three times per day

can reduce depression and anxiety.

There are also some good data out there showing

that theanine can have positive effects

on endothelial cells, so blood vessels,

capillaries, and so on,

and increase some of the functional blood vessels,

allowing them to pass more blood through them

and give them a little bit more elasticity, if you will.

So theanine has certain pro-sleep effects

if it’s taken prior to sleep.

It can enhance the quality, depth, and duration of sleep.

Again, if you’re a sleepwalker

or somebody who has extremely vivid dreams

from which you wake up in the middle of the night,

probably best to leave out theanine

or maybe reduce the dosage down to 100 milligrams.

And if that’s still too much, then eliminate it completely.

But theanine can be terrific

for enhancing quality, depth, and duration of sleep.

It can also reduce the jitteriness

associated with caffeine-containing beverages and foods.

And it has certain antidepressant and pro-endothelial effects

that is it can offset depression, it can offset anxiety,

although those are minor effects, okay, subtle effects.

And it has been shown to improve endothelial cell,

that is vessel and capillary function and structure

in ways that can be beneficial for both brain and body.

Now, one final point about theanine

that’s worth paying attention to

is that the kinetics of theanine are such

that you don’t need to take theanine

every time you ingest a caffeinated beverage.

When we ingest caffeine,

the peak effects of caffeine occur about 30 minutes

after we drink it.

And there, I’m assuming one takes it all at once.

And this is a key point that we’ll come back to later,

rather than sipping your coffee slowly

over a couple of hours or an hour.

If you drink all 200 or 300 milligrams of caffeine

in your coffee or 600 milligrams of your coffee,

if you’re getting one of those commercial coffees,

and you take theanine along with it,

theanine will block some of the jitteriness

and anxiety-inducing effects of caffeine

that can occur for much longer

than the effects that caffeine lasts.

So, the peak in theanine occurs

about an hour after ingestion.

I suppose if you wanted to get really fancy

and really dial in the kinetics,

you could ingest theanine about a half hour

before you ingest your caffeine.

But I think that’s getting a little bit excessive

in terms of controlling your microenvironment, if you will.

I think it would be perfectly fine

to take a 100 to 200 milligram capsule of theanine

along with your coffee or tea and so forth.

And just realize that if you drink more caffeine

or you extend your caffeine intake over several hours,

that you don’t necessarily have to take theanine

repeated times throughout the day.

Let’s talk for a moment about when to avoid caffeine.

And in the same stroke,

let’s also talk about some of the myths around caffeine.

For instance, one of the major myths around caffeine

is that it can increase osteoporosis.

Turns out that while there is a relationship, of course,

between calcium and osteoporosis,

that is reductions in bone density.

And it is the case that caffeine can extract calcium

from certain tissues.

The large scale studies that are out there

essentially prove that if people are ingesting

enough calcium through their diet, which most everybody is,

although certainly there are some people

that need to supplement calcium

or make it a point to consume more calcium-containing foods.

But assuming that you are getting adequate levels of calcium,

there is no direct relationship

between caffeine intake and osteoporosis,

at least not that I’m aware of.

I know this was debated for a number of years

in the literature,

but the literature seems to have arrived

at a general consensus now that caffeine itself

is not going to create or exacerbate osteoporosis,

provided people are getting enough calcium

through their diet, that is through foods,

through supplementation, or both.

Some of the other myths around caffeine

are that, for instance, caffeine will reduce

testosterone levels or will reduce estrogen levels.

Other myths out there are an exact opposite to that,

that caffeine will increase testosterone levels,

in particular, free testosterone levels.

There’ve been some large-scale studies

addressing the hormone effects of caffeine.

They are a little bit difficult to do.

I should just mention that caveat.

And the reason they are difficult to do

is because 90% of adults are consuming caffeine,

and therefore, you can imagine,

it’s very hard to find a control group

to compare the caffeine consumers to,

in particular, a control group

that’s well-controlled for other things

like lifestyle, diet, exercise, et cetera.

However, when one controls as well as one can

for all the various factors that could impact hormones,

what one discovers is that caffeine intake,

at least at the dosages we talked about earlier,

one to three milligrams per kilogram of body weight,

or even up to double that,

that there are no consistent increases or reductions

in testosterone or estrogen in men or women

that can be directly attributed to the caffeine intake.

And I say directly attributed

because in these association studies,

one always has to wonder, for instance,

if because people are ingesting more caffeine,

they have more energy and therefore exercising more

and exercise is known to have effects

on testosterone, estrogen, and other hormones,

whether or not the effects of caffeine on those hormones

is indirect and so on and so forth.

And this all just underscores the challenges

of doing studies on humans in the wild

in their natural habitat of living,

as opposed to an acute study, as it’s called,

to bring someone into the laboratory

and studying them just for those hours or moments.

With all that said, there does appear to be a relationship

between caffeine intake and so-called sex hormone

binding globulin, which is a protein present in the body

of both men and women that binds to the sex steroid hormones,

testosterone and estrogen,

and prevents them from being in their free or active form.

It has been shown that ingestion of caffeine,

even in the sorts dosage ranges that are considered safe

and that we’ve been discussing,

can increase sex hormone binding globulin

such that it can slightly reduce overall levels

of free testosterone and free estradiol in women.

Now, those effects are relatively minor, but they do exist.

If any of you are interested in reading further

into the effects of caffeine on hormones,

I’ll just refer you to a couple of studies.

We will link to this in the show note caption.

The title of the study is consumption of caffeinated

beverages and serum concentrations

of sex steroid hormones in US men.

And within this study, there’s a reference

to a equally sized empowered study done on women,

both of which converged on the same conclusion

by examining more than a thousand.

So in this case, 1,410 men or more than a thousand women

that there are increases in sex hormone binding globulin

associated with increased intake of coffee in particular,

but they were able to narrow that down specifically

to ingestion of caffeine.

So it’s not coffee per se that’s causing the increase

in sex hormone binding globulin.

It’s actually caffeine itself.

Now, again, the increases in sex hormone binding globulin

were not so significant that at least to my mind,

they seem like a concern.

Although I think that it is worth noting

that if you’re going to consume caffeine,

that you probably want to consume caffeine in a way

that is in dosages and with the sort of timing

that will allow you to get away with ingesting caffeine,

but not to excess.

So to derive the benefits of caffeine without, for instance,

driving up sex hormone binding globulin too far.

Now, why would that be a good idea?

Why would you want to make sure

that you have enough free testosterone and free estrogen?

Well, some of that is related to the acute effects

of those hormones in terms of wellbeing and libido

and strength and mood, et cetera.

But some of this also relates to the longer term effects

of sex steroid hormones.

Many people don’t realize this,

but the sex steroid hormones operate on the receptors

at the surface of cells to have immediate effects,

but they also can enter cells

and actually go into the nucleus of cells

where the DNA of those cells are contained

and control gene expression in those cells.

So the sex steroid hormones, testosterone and estrogen

are controlling a lot of different cellular functions

over long periods of time.

So blunting their action over long periods of time

is probably not a great idea.

But again, at the dosages of caffeine

that we’re talking about today,

one to three milligrams per kilogram of body weight,

unlikely that the increases in sex hormone binding globulin

that one experiences from that are going to be detrimental.

And certainly the positive effects of caffeine

that one experiences in terms of mental performance

and physical performance,

and the fact that it increases energy

to do the sorts of things like exercise

that we know can profoundly improve hormone profiles,

twofold or threefold improvement in hormone profiles.

In that case, it seems that ingesting caffeine

is overall a good thing provided it’s not in excess.

That also makes this the appropriate time to mention

one of the more impressive effects of caffeine,

which is on overall levels of mood and mental health.

There are several studies on this,

but the one that I’m particularly fond of

was published in 2019 in Psychiatry Research.

And the title of the paper is Inverse Association

Between Caffeine Intake and Depressive Symptoms

in US Adults.

And these are data from the National Health

and Nutrition Examination Survey.

And the basic takeaway is that while of course

there are a ton of different factors

that are going to relate to whether or not

people are depressed or not,

life circumstances, genetics, and so on,

that, and here I’m quoting from the study,

caffeine’s psychostimulant properties,

that just means the ability to make us feel more alert

and positive, appear to protect against depressive symptoms.

And of course they acknowledge

that additional studies are needed,

but this is just one of several studies

pointing to the fact that people who regularly ingest caffeine

in the appropriate dosages do seem to enjoy

an antidepressive effect overall.

I wouldn’t want anyone to consider caffeine

a treatment for severe depression,

or at least not alone a treatment for severe depression,

but provided the anxiety-inducing effects of caffeine

can be kept in check through use of theanine

or making sure that the dosage

and the timing of caffeine ingestion is correct,

then caffeine overall seems to be good for our mood

and prevent depression or at least keep depression at bay

when depression might otherwise surface or be more severe.

And of course there are the don’ts

surrounding caffeine intake as it relates to sleep.

And to put it very simply,

sleep, that is getting enough quality sleep each night,

is the foundation, it is the bedrock of mental health,

physical health, and performance.

Sleep and the power of sleep far exceeds

any nootropic you could ever take,

any prescription drug you could ever take,

any health-promoting tool for your immune system,

your metabolism, your mental function,

your physical function you could ever take.

Sleep is the bedrock.

I know a lot of people experience challenge with sleep.

Nobody is perfect about sleep,

that’s important to keep in mind.

I think a good goal is to get enough quality sleep

of sufficient duration, 80% of the nights of your life,

and then as much as possible to make sure

that the remaining 20% of nights

you’re not getting enough sleep for good reasons

as opposed to hard reasons.

Good reasons would include raising children,

that’s important.

After all, every species desires to make more of itself

and to preserve and extend the wellbeing of its young,

so child-rearing is a perfectly legitimate reason

to get a lack of sleep,

but you really want to strive to get quality sleep

most nights of your life,

which means that even if you’re somebody

who can quote-unquote drink an espresso

and then fall right asleep,

that you avoid caffeine intake

in the 12 hours prior to sleep.

I realize not everyone will be able to do that,

and in fact, I sometimes violate that,

so I tend to go to sleep around 10 p.m. every night,

sometimes 11, occasionally 12 midnight,

but usually around 10 p.m. every night.

I confess that my last ingestion of caffeine

is not always 10 a.m. or prior to that,

so sometimes I will have caffeine up until 11 a.m.

or maybe noon, and very, very rarely

I’ll have an afternoon coffee or espresso

or non-calorie-containing soda or tea

or something of that sort,

but I really try to restrict my caffeine intake

to the early part of my day, that is before noon,

given that I go to sleep around 10 p.m. each night,

and I strongly encourage everyone out there

to try and limit their afternoon caffeine intake.

This is something that Dr. Matt Walker,

who’s an expert sleep researcher

out of University of California, Berkeley,

Psychology and Neuroscience Department there,

author of the incredible book, Why We Sleep.

He’s been on this podcast, many other podcasts,

talking about the importance of sleep.

He will remind us, and I’ll remind you now,

that the quarter-life of caffeine is 12 hours.

I mentioned this earlier, but I’m going to repeat it again,

and that means that if you ingest caffeine at noon,

25% of its effects, more or less,

I’m using a broad stroke here to talk about quarter-life,

25% of that is still going to be bioactive

at midnight that night,

which will disrupt the early phase of your night,

the amount of slow-wave sleep,

which then in turn will disrupt

the amount of rapid eye movement sleep,

which will disrupt your emotional processing

during the following day, and so on and so forth.

None of this is to say

that if you have the occasional cup of coffee

in the afternoon, that it’s going to completely demolish

your sleep-wake cycle forever,

but I really encourage people to avoid drinking caffeine

in the 12 hours prior to sleep,

and if you can’t do that within the 10 hours prior to sleep,

and if you can’t do that

within the eight hours prior to sleep,

so really try and limit your caffeine intake

in the eight to 12 hours prior to going to sleep at night.

And of course, slow-wave sleep, aka deep sleep,

is the sleep that’s associated with somewhat mundane dreams,

which makes it sound like it might not be that important,

but it’s also the sleep that’s associated

with growth hormone release,

which is important for protein synthesis,

repair of all bodily tissues and metabolism,

and slow-wave sleep is also critically attached

to your immune system’s ability

to clear out bacteria and viruses

that might otherwise infect your tissues.

Now I’d like to talk about caffeine

and its positive effects on performance

when used correctly, and here we are referring

to both mental performance and physical performance.

The exploration of caffeine as a pro-performance tool

has been explored since the 1930s,

at least that’s some

of the earliest documented literature on this,

although I have to imagine,

given that people have been using caffeine

for much longer than that,

that long ago somebody realized

that by ingesting a certain plant

that they felt much more alertness

and were able to hunt and gather

or do any number of different things better,

and as a consequence,

decided to consume more of that plant.

Now, these days we consume a lot of caffeine

in the form of coffee and tea mainly,

and some people consume it in the form

of caffeine tablets or energy drinks, et cetera.

Across the board, one finds that caffeine intake

at a level of one to three milligrams per kilogram

of body weight improves reaction time,

that is it reduces the amount of time

to take a physical action

or to answer a question correctly with a verbal response.

It can also improve coordination,

it can also improve memory,

although I do want to mention that whereas most studies

of the effects of caffeine on improving mental

and physical performance involve taking caffeine

at one to three milligrams per kilogram of body weight

before the mental task or physical task,

there is also a pro-performance effect of caffeine

on memory if one takes caffeine

after learning certain material,

or I should say being exposed to certain material.

We’ll come back to that in a few minutes.

If one examines reaction time, mood, alertness,

focus, and memory or the ability to call up information

from memory or physical dexterity, power output, endurance

and overall feelings of wellbeing during exercise

and exertion, caffeine has been shown in numerous studies

in both men and women to improve all

of those metrics significantly.

So this is all just to say

that caffeine is an incredible performance enhancing tool.

Now, what’s not obvious from the statement

that caffeine is a performance enhancing tool

across the board and in men and women

and in different contexts is that the way

in which caffeine is taken is very important.

Because 90% or more of adults consume caffeine,

finding controls for studies of caffeine

is really challenging.

That is finding people who don’t ingest caffeine regularly

is a very challenging task for the researcher.

And as a consequence, many of the studies of caffeine

on human beings involve depriving regular caffeine users

of caffeine and then examining the effects of caffeine given

after a period of say five to 15 days of abstinence

in a person that is essentially experiencing

mild withdrawal symptoms because they haven’t had

the caffeine that they were used to getting.

So this is an important point.

And it’s a point that likely exacerbates

the observed pro-performance effects of caffeine.

Now, all of that isn’t necessarily a problem

provided you keep it in mind.

And it actually points to a way in which

even if you’re a regular caffeine user,

you can extract more of the benefits of caffeine.

The simplest way to do this, for instance,

is to look back to what we talked about earlier

in terms of the need to have most

of your cortisol increase restricted to the hour or hours

just after waking in terms of mood

and alertness and performance.

One of the ways to increase the peak of that cortisol

early in the day is to consume caffeine shortly

after that peak occurs.

And this was really nicely demonstrated in a study

entitled Caffeine Stimulation of Cortisol Secretion

Across the Waking Hours in Relation to Caffeine

Intake Levels.

We will provide a link to this study.

It’s a somewhat complicated study

because they looked at a bunch of different times of day

for caffeine intake.

And I should mention this study,

they use this 300 milligrams per day

or 600 milligrams per day.

So that’s quite high,

although for people of sufficient body weight

and who are accustomed to taking caffeine,

it’s certainly not going to be in excess

of what a lot of people out there are taking.

But basically what they observed was the following.

Cortisol responses to caffeine are reduced

but not eliminated in people who consume caffeine

on a daily basis.

What this means is that if you wake up

and as I recommended earlier,

you avoid drinking caffeine for the first 90

to 120 minutes after waking,

but you do get some sunlight or other bright light

in your eyes in that time,

maybe even get some exercise in that time,

which would be even better.

And then you ingest caffeine,

you’ll get a further increase in cortisol,

which provided it’s restricted to the early part of the day

is a good thing overall for mood and alertness.

So this is a simple performance enhancing tool,

which is to stack caffeine on the tail

of that early cortisol peak.

I should also mention, however, that in this study,

they had people do a five-day caffeine abstinence

prior to being tested with 300 milligrams

or 600 milligrams of caffeine.

So the simple tool to extract from this

and other studies like it,

is that if you want to experience

the maximum alertness promoting effects of caffeine

when you ingest it early in the day,

you would abstain from caffeine for five days

and then ingest caffeine 90 to 120 minutes after waking.

I would still hope that you were doing

all the other things that I described,

morning sunlight, exercise, et cetera, correctly.

But regardless, it’s very clear

that a five-day abstinence from caffeine,

however painful that might be,

will increase the performance enhancing effects of caffeine

when you take caffeine on that sixth day.

Now, I’m sure many of you out there are saying,

why would I ever want to abstain from caffeine

for five days in order to just get

this six-day performance enhancing effect?

Well, there are a couple of reasons for doing that.

Perhaps you’re planning to travel to a new time zone

and you want to use caffeine as a stimulant

to stay up during the day in the new time zone.

That’s a somewhat unusual case.

Others of you might be interested

in the pro-physical performance effects of caffeine.

We’ll talk more about these in a little bit,

but you want to get the maximum strength increase

or the maximum endurance increase from ingesting,

in this case, 300 to 600 milligrams.

Well, in that case, abstaining from caffeine for five days

will greatly exacerbate the pro-performance effects

of caffeine when you take it on that sixth day.

Although, admittedly, those five days

are likely to be pretty painful

if you’re a regular caffeine user.

Another variation on this, however,

might be to halve the amount of caffeine

that you ingest on a daily basis

and then go back to your regular level of caffeine intake

on that day in which you need the caffeine

to really boost your mood, energy, and performance.

Another reason why you might want to abstain from caffeine

or reduce your caffeine intake for a period of time

and then go back to your regular caffeine intake

is simply to identify how much of an effect

caffeine is really having on your overall level

of daily functioning and mood.

This was something that was actually covered

in beautiful detail in a book by Michael Pollan

all about caffeine.

It’s available on Audible.

I really enjoyed that book.

It describes his experience with the decision

to completely abstain from caffeine for a period of months.

Although, I confess that after hearing that book,

what it basically made me want to do

is never quit drinking caffeine

because it sounded as if, at least my interpretation was,

that even after several weeks or months

of abstaining from caffeine,

that he still fantasized about the effects of caffeine.

But he did mention that when returning to ingesting caffeine

after a period of long abstinence,

that it had almost a, let’s not call it a psychedelic

property, but it had such obvious effects

on mood and alertness and feelings of wellbeing

that it really highlighted for him

the extent to which caffeine normally was allowing him

to just function what he thought was normally.

So in other words, many of us don’t even really know

what our normal basal level of cognitive

and physical functioning is

because we’re ingesting caffeine on such a regular basis.

I confess that as much as I enjoyed that book

and as intriguing as his description of caffeine abstinence

and then the return to caffeine was,

I don’t intend to ever find out personally.

Now, a very good reason why you might want to abstain

from caffeine for a deliberate period of time

and then return to caffeine intake

is for its physical performance-enhancing effects.

And here we can look to a really interesting study,

title of which is Time Course of Tolerance

to the Performance Effects of Caffeine.

And what I like about this study is that while, yes,

it does say that abstaining from caffeine

and then returning to caffeine intake

can enhance physical performance in a very specific way,

it also says that if you take caffeine regularly,

you can still see the physical performance-enhancing effects

of caffeine, although they are not quite as robust

as they would be had you abstained from caffeine.

The design of the study is pretty straightforward.

They had people either ingest three milligrams

per kilogram of caffeine for 20 consecutive days.

Many people are already doing that, I realize,

but they had people do that

or ensure that they were doing that

or others ingested a placebo for 20 days.

So they abstained from caffeine without realizing it.

Then after that 20 days of either ingesting caffeine

or a placebo, their peak performance was measured

in terms of aerobic output,

but prior to that measurement, they had caffeine.

Okay, so it’s 20 days of caffeine

and then a 21st day of caffeine

and then the physical task on that 21st day,

or it’s 20 days of abstinence from caffeine

and then on day 21, you get caffeine

and you get the same physical test.

And what they discovered was that the ingestion

of caffeine increased peak performance

in this aerobic output dramatically

if people had abstained from caffeine,

but for people that had consumed caffeine

all the way through up until that day,

it still was effective to ingest caffeine on day 21,

but not as effective as it would have been

had they abstained.

And in fact, the magnitude of the,

what they call ergogenic effect,

which is the pro-performance enhancing effect of caffeine,

was higher on the first day than in subsequent days

when they allowed people to continue caffeine intake.

So the takeaway from this study is really straightforward.

If you want to get the maximum physical performance

enhancing effects of caffeine,

you abstain from caffeine for 20 days,

then on day 21, when you’re going to do the physical thing,

the task, you ingest caffeine about 30 minutes to an hour

before you do that physical challenge.

Now, 20 days of abstinence is going to be rough

for a lot of people.

I certainly don’t want to sign up for this study,

in which case you might want to do five days of abstinence

as we talked about before.

And then on day six is the day that you ingest caffeine

and do the physical task.

There are even some studies showing

that you can abstain from caffeine for just two days,

for just 48 hours.

And in particular, if you are a regular user of caffeine,

this allows you to, on day three, ingest caffeine

at the dose that’s appropriate for you

and do the physical,

or I should mention mental performance task

and perform significantly better

than those that have been taking caffeine

throughout the entire period leading up to the challenge.

So you don’t necessarily need to abstain for 20 days

in order to get the pro performance effects of caffeine

on day 21.

You could do five days of abstinence prior

or even two days of abstinence prior,

or if that’s intolerable to you,

as it is in my mind to me,

to just reduce your caffeine intake slightly,

or even perhaps have it, if you can tolerate that,

in the week or two weeks,

or maybe even three weeks preceding

some physical or mental challenge.

Now, again, this sort of implies

that you’re going up against a marathon

or you’re going up against a series of long tests,

maybe standardized tests in one day.

There, I just really want to point out

that there is an abundant literature

showing that people perform best on mental tests

if they are in the state that they were

when they studied for that material.

Now, in college, I knew a number of people

who took this to the extreme,

thinking that if they were to study

under the effects of alcohol,

that they would be best off consuming alcohol

prior to taking exams,

and it turns out to not be the case.

Here, we’re talking in particular

about psychostimulant effects of caffeine

and other compounds.

So don’t think that you can drink

or be under the influence of THC

and then take, when you study,

and then take an exam under the same influence

and do just as well as you would

had you not ingested anything.

Please don’t let that be the takeaway.

However, do let it be the takeaway

that caffeine’s effects are made more potent

by a brief to not-so-brief period of abstinence

prior to taking a dosage of caffeine.

And then the final point to make

is that if you are somebody

who is not accustomed to drinking caffeine,

meaning you’re hypersensitive to caffeine

or you don’t regularly ingest caffeine,

please do not ingest caffeine

on the day of any important mental

or physical challenge or performance,

because what you will find

is that because you are not caffeine-adapted,

you will experience changes in your thermal regulation,

in your levels of anxiety and jitteriness,

and your levels of focus

that could be very detrimental

to mental or physical performance.

So you don’t want to throw yourself in the deep end

by ingesting caffeine if you’re not used to it.

And I should mention that for people

that are not accustomed to ingesting caffeine

or are very sensitive to caffeine,

even 25 to 50 milligrams of caffeine

in the amount that’s found in, for instance,

a piece of certain types of chocolate

can actually cause anxiety.

So be careful there.

Here, I’m referring only to people

that are accustomed with caffeine intake.

So what I recommend is to explore

the ergogenic effects of caffeine during your training,

and then to make a decision

about what you can reasonably and reliably do

in terms of abstinence,

and then pulse with caffeine on the day of the challenge.

I get a lot of questions as to whether or not caffeine

has different effects on the nervous system

and on performance in particular,

depending on phases of the menstrual cycle.

So I explored that in my research for this episode,

and I found two studies,

both of which we will reference in the show note captions.

The first one is entitled

Caffeine Consumption and Menstrual Function.

So it’s actually the relationship

between caffeine and menstrual function.

We will do an entire episode

about the menstrual cycle and menstrual function.

But the other one, as it relates to performance,

was published in 2020 in the European Journal of Nutrition,

which is Ergogenic Effects of Caffeine

on Peak Aerobic Cycling Power During the Menstrual Cycle.

And the basic takeaway of this study,

this is frankly a very nice study,

showed that, quote,

“‘Caffeine increased peak aerobic cycling power

in the early follicular, pre-ovulatory,

and mid-luteal phases of the menstrual cycle.

Thus, the ingestion,”

and again, here they use three milligrams of caffeine

per kilogram of body mass,

“‘might be considered an ergogenic aid

for women who are in the menstrual cycle

during all three phases of their cycle.’”

So keep that in mind.

Women, for those of you that are regular users of caffeine

or you’re using caffeine to enhance physical performance,

there does not seem to be any menstrual cycle

phase-dependent effects of caffeine on performance.

That is, caffeine seems to always increase

physical performance,

regardless of the phase of the menstrual cycle

you might happen to be in.

I’d like to touch on a little bit more

of the use of caffeine for enhancing mental performance.

Yes, it is the case that ingesting one to three milligrams

of caffeine per kilogram of body weight

in the 30 minutes or so prior to doing a memory task

or sitting down to doing some studying

or learning of any kind,

physical or mental performance of any kind,

is beneficial for all the reasons we talked about before,

related to dopamine and acetylcholine, et cetera.

But it turns out that it is also the case

that spiking one’s adrenaline

and other so-called catecholamines,

so this would be dopamine, norepinephrine, and epinephrine,

after a bout of learning,

can greatly enhance memory for the information

that one was trying to learn.

That’s right.

Spiking your adrenaline after learning

can greatly increase memory

for the material you’re trying to learn.

In fact, this is a practice that dates back centuries

and was written about

in a beautiful annual review of neuroscience

on the biology of memory by James McGaugh,

where he talks about medieval practices

of children being taught information

and then being thrown, literally, into cold water

to stimulate the release of adrenaline

and that increase in adrenaline,

while the mechanism wasn’t completely understood,

it was understood that that sort of shock to the system

from the cold water led to better memory

and retention of the information

that these children had been exposed to.

And it turns out the exact same thing is true for adults

in the laboratory or kids in the laboratory.

And here, I’m not suggesting throwing anyone

into cold water.

If you want to get into cold water,

there’s a reason we call it deliberate cold exposure

on the podcast is that it should be deliberate

and controlled by you, not by somebody else.

If it’s controlled by somebody else,

that might be military screening or something.

But here we’re talking about deliberately increasing

your levels of adrenaline and other catecholamines,

dopamine, norepinephrine, et cetera.

You can do that certainly by deliberate cold exposure

with a cold shower or getting in up to your neck

in cold water of any kind.

But the other way to do that is to spike your adrenaline

by ingesting one to three milligrams per kilogram

of caffeine after sitting down

to try and learn some material.

I confess that more often than not,

I use caffeine the same way that most people use it,

which is, okay, I’m going to sit down,

I’m going to research information for a podcast

or assemble some information for a paper or grant,

and I want to focus.

So I will drink a cup of coffee at the beginning of that,

and maybe even throughout that,

or a couple of yerba mate at the beginning

or throughout that, or I’ll sip on one or both

throughout trying to learn.

And that works quite well in terms of maintaining focus

and alertness and retention of information.

But it is indeed the case,

that is the research supports the fact,

and I’ve experienced the fact,

that if I abstain from caffeine

while I’m trying to learn something,

but then I drink caffeine immediately after,

somewhat surprisingly to me,

but certainly in a way that’s consistent

with the research literature,

memory for the information that I was focused on

prior to ingesting that caffeine is much greater.

And here I’m talking about it as a personal anecdote,

but this is actually what the data point to

both in animals and in humans.

And if you think about it, it makes perfect sense,

because the way that the memory systems

of the brain are organized

is that we go through life experiencing things,

we encounter surprises, both good and bad,

we go through the motions of things,

both typical, mundane, exciting,

and novel and not novel.

And then every once in a while,

something will happen that will spike our catecholamines,

dopamine, typically if it’s a positive surprise,

adrenaline, which can be associated

with both positive surprise or positive events

and negative events or surprises,

and without fail, increases in the catecholamines

tend to lock in memories for things that preceded

the increase in those catecholamines.

Again, the catecholamines being dopamine,

epinephrine and norepinephrine,

sometimes all three in combination,

sometimes just two of those,

sometimes just one of those, depending on the experience.

So it makes perfect sense that using caffeine

at the end of a learning bout would enhance our memory

for the information that we’re trying to learn.

So if you decide that you want to try and extract

this performance enhancing effect of caffeine,

what I recommend would be to try and abstain from caffeine

for a day or two prior,

but if you can’t, to just continue

with your normal caffeine intake.

But then when you sit down to study or learn something,

to not ingest any caffeine as you do that,

but then afterward to ingest caffeine.

Now, in theory, you could probably further enhance

the memory encoding effects of adrenaline

and the other catecholamines by drinking caffeine

and then taking a cold shower,

doing deliberate cold exposure if you really wanted to

or had the ability to,

or doing some sort of intense form of exercise.

And we’ll talk in a moment about how caffeine exercise

and the adrenaline system interact.

But as a brief, but relevant aside,

brief bouts of intense exercise,

ranging from 10 to 50 minutes or so,

have been shown to improve memory for information

that one was trying to learn prior to the intense exercise.

This is work from Dr. Wendy Suzuki’s lab at NYU,

as well as other laboratories.

Some of the work that’s being done at Stanford

in the mind-body laboratories.

And our laboratory points in the direction

of these kinds of effects as well.

They all come back to the same general neurochemical theme,

which is that when we experience an increase

in these catecholamines that include adrenaline,

dopamine, and norepinephrine,

the memory systems of the brain flip on

in a way that try to capture the information

and the perceptions and the experiences

that we were exposed to just prior

to the increase in catecholamines and caffeine,

but also exercise and also cold water.

And of course, any of those alone or in combination

all increase the levels of catecholamines.

So it makes perfect logical mechanistic sense

as to why this would work.

And in fact, it does work.

If you want to remember specific information,

you might consider using caffeine

as you move through and absorb

and are exposed to that information,

but you might also consider using caffeine

after being exposed to that information

because studies in animals and humans

show that that is a potent way to increase memory

for what you were just exposed to.

I should mention that what I just described

also pushes back on something

that I know a number of people perhaps have heard about

and maybe even use, which is this notion of the nappuccino.

I remember hearing about this a few years back.

It was a sort of trend, if you will.

The trend involved drinking a cup of coffee

or double espresso and then going down for a nap,

typically in the afternoon, and then waking up.

And the idea was that the caffeine would hit your system

right at the time that you awake from the nap

and that you would be better able to focus and exercise.

There are a couple of things about that practice

that I don’t like.

First of all, it implies in most cases

that you’re napping and ingesting caffeine in the afternoon,

which I realize for many students

and for people that are comfortable

staying up until the wee hours of the night

and then waking up late the next day

might be compatible with their schedule.

But again, because of the sleep

diminishing effects of caffeine,

and we talked about earlier,

I’m not crazy about the idea of people

ingesting caffeine in the late afternoon

in order to perform better in the late afternoon.

Far better would be to restrict caffeine intake

to the early part of the day, as we talked about earlier.

The other reason is that the data

on things like non-sleep, deep rest

and naps in the afternoon.

And again, the rule here is that you don’t have to nap,

but if you want to nap,

it’s been shown that naps of 90 minutes or less

or non-sleep, deep rest protocols,

and you can find those, for instance,

there’s one with me speaking,

you just put NSDR Huberman into YouTube,

you can hear that, it’s completely zero cost.

There are other NSDR scripts out there now, of course,

that if you prefer those,

that those can all lead to increases

in one of the catecholamines at least, which is dopamine.

That’s been shown in a really nice

neurotransmitter labeling study,

not from my laboratory, but from another laboratory,

but also can improve mood focus and alertness

on its own without the need to ingest caffeine

prior to going into those states.

And in fact, ingesting caffeine prior to a nap

or ingesting caffeine prior to NSDR

is most certainly going to reduce the effectiveness

of that nap and NSDR in restoring natural levels

of alertness and focus that would lead

to the performance enhancing effect.

So I’m not such a fan of the so-called nappuccino,

although if any of you out there

have derived great benefit from it,

definitely let me know your protocol

and what you’ve experienced.

Put it in the comment section, if you would.

I’d appreciate that.

There’s another very important and potent use of caffeine

for enhancing performance.

And this relates not just to the dopamine and epinephrine

and the arousal inducing effects of caffeine.

And it doesn’t even just relate to the effect of caffeine

on enhancing frontal lobe function.

It does include all that,

but it also includes those reinforcing effects of caffeine

that we talked about at the beginning of the episode.

And the best way to illustrate

these performance enhancing effects of caffeine

that stem directly from its association with reinforcement

is to highlight a study.

And the title of the study is blood dopamine level

enhanced by caffeine in men after treadmill running.

And as the title suggests, this was carried out in men,

but there’s no reason to think that the same results

wouldn’t also be present in women.

There are some sex dependent effects of caffeine.

I’ll touch on just briefly at the end,

but those are largely present in kids.

That is adolescents and teens, as opposed to adults.

So this study is really interesting.

What they had people do was run on a treadmill

and either ingest caffeine again,

three milligrams per kilogram of body weight,

or to not ingest caffeine.

And then they looked at levels of dopamine

and other neurotransmitters and hormones,

such as prolactin and cortisol.

And the basic takeaway is, as the title suggests,

that exercise while on its own can increase cortisol

in healthy ways, provided it’s not too intense and too long.

Little note here,

if you have trouble recovering from exercise

or you want to continue to derive

the benefits from exercise,

in general, best not to do high intensity exercise

for longer than 75 minutes or 90 minutes,

probably being the outer threshold.

I realize that there are some genetic freaks out there

or people that are chemically assisted

that can recover from very intense long bouts of exercise,

but most people don’t do well

long bouts of intense exercise on a regular basis

and limiting their intense exercise to 60 minutes or less,

that doesn’t include the warmup, is going to be beneficial.

See the episode on a toolkit for fitness

if you’d like details on that.

Exercise is known to increase levels of dopamine,

cortisol, and other catecholamines

and neurotransmitters very potently.

And things like testosterone and estrogen

in ways that we know are beneficial to us.

And of course have all these positive effects

on the musculoskeletal system and cardiovascular effects.

But unbeknownst to most people,

ingesting three milligrams per kilogram of caffeine

prior to exercise further increases the dopamine release

associated with exercise specifically.

And this has two important effects.

First of all, that increase in dopamine is great

because it provides a long lasting increase

in focus, alertness, and motivation,

not just during the exercise, but also after the exercise.

And second, it, that is caffeine and dopamine in combination

act as a reinforcer to make the experience of exercise

and the period immediate after exercise more pleasant

and in fact, reinforcing.

So in other words, one way to enjoy exercise more

and to enjoy the activities that follow exercise more

and to experience a genuine increase in dopamine

that’s beneficial for mood and alertness

is to ingest caffeine prior to exercise.

Now, this is important because a number of people out there

are exercising, love exercise, love eating great,

love doing all the things that are beneficial

for their health.

But a number of people out there

really don’t like to exercise.

And that serves as a serious block for their willingness

and their consistency to exercise.

Ingesting caffeine gives us energy to exercise.

It increases the release of neurochemicals and hormones

that are good for us during exercise.

But as I’m highlighting here,

it also increases the reinforcement pathways

associated with exercise.

That is, it creates a positive feeling

about the general theme of engaging in exercise.

And it creates a general positive experience

of the things that follow exercise.

So I think this, if nothing else,

is a call for or support for the idea

that ingesting caffeine as a performance enhancing tool

makes perfect sense.

But for those out there that don’t enjoy exercise,

in particular, certain forms of exercise,

ingesting caffeine can change your relationship

to that exercise.

In other words, make it more positive,

much in the same way that ingesting caffeine

alongside a certain taste

that would otherwise be neutral or maybe even negative

can actually make the taste of that particular drink

or food positive.

So again, this brings us back

to the reinforcing properties of caffeine

that are subconscious.

It’s not just about the enhanced performance in the test

or the enhanced performance on the treadmill

or with the weights in the gym.

It’s enhanced feelings of mood and wellbeing

that are genuine because of the effect of caffeine

on certain neurotransmitter and hormone systems.

But it also is creating an overall milieu

of reinforcing all of the things that led into,

occur during and occur after exercise.

I do want to point out something that’s very important

as it relates to combining things like caffeine

and exercise in order to increase dopamine.

This is something that came up in the episode

that I did on dopamine motivation and drive,

which turns out to be one of our most popular episodes.

Again, you can find that at hubermanlab.com

and links to all formats with timestamps, et cetera.

This also came up in the episode on ADHD

because of the relationship between ADHD and dopamine.

And that’s this notion of dopamine stacking.

In the episode on dopamine motivation and drive,

I pointed out that while there are a near infinite number

of things that can increase dopamine release,

most notably positive surprise or positive anticipation

or experiencing a win,

certainly there are compounds, both drugs of abuse,

food, sex, and certain supplements

that can increase dopamine to varying levels

and to varying degrees, both healthy and unhealthy.

That’s all contained in that episode

on dopamine motivation and drive.

But what I pointed out is that if you are somebody

who tends to experience difficulty with motivation,

that so-called dopamine stacking, as I called it,

might be something that you want to avoid.

What is dopamine stacking?

Dopamine stacking would be combining

a highly caffeinated energy drink

that also includes the amino acid tyrosine,

which is a precursor to dopamine, plus loud music,

plus getting yourself really ramped up

then an intense workout.

All of that can be great if you do it every once in a while.

But what you will quickly find is that the extent

to which your dopamine peaks also dictates the extent

to which your dopamine will drop after that peak.

And when I say drop, I mean drop below baseline.

So a lot of people find that if they stack a lot of things

to peak their dopamine, that then they experience a low

and it does take some time for them to return to baseline.

And I highly recommend not engaging in activities

or consuming compounds that are in attempt

to accelerate that return to baseline

because all it will do is drive

that baseline lower and lower.

So this requires being able to tolerate a drop

in dopamine baseline for a period of time, et cetera.

Now, the reason I’m bringing this up now

in the context of this caffeine episode

is I just described a study

in which using caffeine prior to exercise

increases dopamine after exercise.

And so you might be saying,

especially if you heard that earlier episode,

wait, isn’t that dopamine stacking?

Aren’t you encouraging me to stack my dopamine?

Well, in some sense, yes, but keep in mind,

I’m not suggesting that you do this every time you exercise.

So just as in that earlier episode,

I emphasized the fact that while stacking multiple stimuli,

right, caffeine or energy drinks and music and et cetera,

for exercise or for mental work

or for any experience for that matter

is okay to do every once in a while for most people.

You don’t want to get in the habit

of doing it consistently every time you exercise

or every time you go out, for instance.

And so you really want to be cautious.

That is you want to protect your both baseline levels

of dopamine and your peak levels of dopamine.

That said, for people that want to experience

an increase in mood, alertness and performance

or who want to condition themselves

because that’s really what it is.

It’s conditioning yourself

by the reinforcing effects of dopamine

to increase your liking

or maybe even your loving of exercise,

occasionally using caffeine

or frequently using caffeine prior to exercise is fine,

but be very careful.

And by being very careful,

what I mean is pay attention to how you feel

in the hours and days after

that dopamine increase wears off.

So for instance, if you ingest caffeine

and then exercise very intensely

and you’re feeling great afterwards,

but then eight hours later or the next day,

you’re feeling a little bit low,

I suggest you don’t go back

and do the exact same thing right away.

I would give yourself a little bit of time

to let that baseline of dopamine return to normal.

So again, stacking different things,

chemical and behavioral in order to increase dopamine

can be done in a safe way that’s beneficial to you

depending on your goals,

but be careful about not stacking too many stimuli

for dopamine too often, that’s the key.

Early in the episode,

I mentioned one possible caffeine consuming schedule

that works very well,

that doesn’t fortunately subject you

to long 20 day bouts or five day

or even two day bouts of abstinence.

And that’s the every other day schedule of caffeine.

If you look at the half-life of caffeine

and you look at its effects on the dopamine system

and its performance enhancing effects

and how a period of abstinence

can in fact increase the performance

enhancing effects of caffeine,

but also take into consideration

that caffeine can be habit forming

and we can develop a sort of tolerance to caffeine.

Well, then what emerges from all of that

is that being a person who consumes caffeine

every other day can actually help you maximize

most of the positive effects of caffeine

without subjecting you to the kind of misery that occurs

if you’re accustomed to consuming caffeine every single day

and then suddenly go into a two or five

or 20 day abstinence.

So I myself have never tried

an every other day caffeine approach,

although I’m considering doing it

based on the literature that I’ve read.

And I’m considering doing it in a very specific way,

which will be to only consume caffeine

on the days in which I resistance train.

And since I tend to do that

about three or four days per week

organized in a way that’s every other day.

Again, if you want to see the exercise schedule

that I follow, including cardiovascular exercise

and weight training and all the reasons

and rationale for what I do

and how it maps onto the scientific literature

related to health span and life span, vitality, et cetera.

You can find that at hubermanlab.com.

And we had a toolkit for fitness

that ought to be posted to our website before long.

The every other day schedule of caffeine intake

to me seems like the most rational one.

If one wants to maximize on the performance

enhancing effects of caffeine

without suffering the effects of caffeine withdrawal

that are associated with being a regular consumer of caffeine

and then stopping caffeine intake,

such as headache and irritability and so forth,

not I nor anyone in my life

wants me to experience those effects.

And I’m sure you don’t want to experience

those effects for you either.

So if you’re somebody that decides to try

the every other day protocol,

or you are somebody who’s already doing that protocol,

please let me know what your experiences with that are.

At least by my read of the literature on caffeine

and its performance enhancing effects,

but also the effects of caffeine

on neurotransmitter and hormone systems.

The every other day caffeine’s schedule

does seem to be the most rational

and scientifically grounded one

in order to maximize on all those effects.

In addition to so-called performance enhancing effects

of caffeine, there are also the well-studied

and now fairly well mechanistically understood

pro-health effects of caffeine.

Now here, when I talk about pro-health effects of caffeine,

I want to be very clear that if your schedule

of caffeine intake, that is your timing of caffeine intake

or anything else for that matter,

offsets getting regular high quality sleep

of sufficient duration, well then you are undermining

the pro-health effects of that thing.

This is true for exercise, this is true for caffeine,

this is true for supplementation,

this is true for prescription drugs.

Again, you don’t want to be neurotically attached

to the idea that you have to get perfect sleep every night

because that’s simply not true,

but it is absolutely the case that anything,

whether or not it’s good for you or bad for you

in the short term, that disrupts your sleep

because of the timing in which you’re doing that thing

is going to undermine your immediate

and long-term health before long.

So with that said, there are several well-described

health promoting effects of caffeine ingestion.

And once again, when I say caffeine ingestion,

I’m referring to that one to three milligrams per kilogram

of body weight dosage.

There are really nice studies showing

that being a regular consumer of caffeine

can help offset some of the probability,

some of the probability of developing Parkinson’s

and maybe Alzheimer’s related dementia as well.

These are not terribly controversial data

because of the fact that caffeine is known

to increase the release of those catecholamines,

dopamine, epinephrine, and norepinephrine,

as well as acetylcholine.

All those neurotransmitter and neuromodulator systems

are the ones that are known to be defective

in Parkinson’s and Alzheimer’s,

although there are other transmitter and hormone systems

that are defective as well.

There are beautiful reviews on the neuroprotective effects

of caffeine and neurodegenerative diseases.

They’re quite extensive.

And I’ll just refer you to one and the references therein,

and we’ll provide a link to this in the show note captions.

So the title as the topic at hand suggests

is the Neuroprotective Effects of Caffeine

and Neurodegenerative Diseases.

This was published in 2016.

I’m sure there’ve been other reviews since then,

but it includes many, many quality references

and studies both in animals and in humans

pointing to the fact that specific enzymes

that are associated with the health

of in particular dopamine neurons

are made more robust by regular ingestion of caffeine.

It also points to the fact

that the increase in dopamine receptors

that is induced by regular ingestion of caffeine

that I referred to earlier

is another way in which dopamine,

however many dopamine neurons remain around

in people with Parkinson’s or people who are aging

that lose dopamine neurons naturally,

that dopamine can have its maximal effect

because of the increase in receptors for dopamine

that caffeine induces.

And there are other biological mechanisms

that further support why caffeine

ought to be neuroprotective,

including its effects on the acetylcholine system,

which is one of the major systems

disrupted in Alzheimer’s dementia.

So in other words, it makes perfect sense

as to why caffeine would be neuroprotective.

Caffeine has also been shown to diminish headache,

particularly when taken in combination with aspirin.

And that’s because of the effects of caffeine

and aspirin on blood flow.

There’s also evidence that caffeine can provide brief

but substantial relief from asthma.

So I wouldn’t want people to rely on caffeine

as a life saving approach to an asthmatic attack.

That said, for people that suffer from minor asthma,

that caffeine intake, again, of the dosages

that we talked about before,

has been shown to alleviate some of the major symptoms

of asthma for anywhere from one to four hours.

And I know this is of relevance

to a lot of people out there.

Because caffeine increases the catecholamines,

and in particular because caffeine increases

dopamine transmission in the prefrontal cortex,

this area of the brain associated with focus

and rule setting and context and task switching,

caffeine is known to improve focus and alertness,

in particular in people who have symptoms of ADHD

or other attention and focus issues.

Now, caffeine alone does not appear to be as potent

for the treatment of ADHD as are things like

ritalin, Adderall, modafinil and armodafinil and Vyvanse.

If you would like a sort of head-by-head comparison

of prescription drugs, supplements and things like caffeine,

as well as coverage of behavioral tools

and nutritional tools, et cetera,

that can positively offset some of the symptoms of ADHD,

please see the episode that I did on ADHD.

Again, that’s available at hubermanlab.com in all formats.

But that said, caffeine does increase focus

and it does it through a number of different mechanisms,

not the least of which is to increase dopamine transmission

in the forebrain,

just as a drug like ritalin or Adderall would,

although not to the same extent

as a drug like ritalin or Adderall does.

Before we close today,

I do want to just briefly return

to the reinforcing effects of caffeine

that we talked about earlier.

This study on the honeybees that showed that

bees prefer certain nectars because they contain caffeine,

even though they are not aware

that those nectars contain caffeine.

They just come to like the feeling

that those nectars provide them so much

that they associate that in a subconscious way

with the flowers themselves

and they come to like those flowers.

Or human beings, for instance,

children that ingest caffeinated beverages

come to adore the taste of those beverages.

And beautiful studies have been done

that describe how children and adults

truly cannot distinguish between the taste

of a caffeinated and non-caffeinated beverage.

And caffeine can be placed into essentially any beverage

in order to give us a preference for that beverage or food.

In fact, the studies have been done with yogurt.

If you put caffeine into yogurt of different flavors,

even plain yogurt, which most kids don’t like,

they will come to prefer

whatever flavor contain the caffeine,

even if then you remove the caffeine from that flavor.

Now, eventually their preference

for that flavor will be extinguished.

But all of this is just to say

that so many of the things that we like,

whether or not it’s coffee or tea

or a given flavor of food or given experience

or even exercise occur

because we ingest caffeine in conjunction

with those activities.

Now, these are not tricks

that your nervous system plays on you.

These are real neurochemical reinforcing effects.

And I think that we would all do well to think about

and to leverage these reinforcing effects

much in the same way we would do well to think about

and hopefully not leverage aversive effects

of certain compounds, right?

The simple way to put this is,

I or anyone could get you to dislike something,

someone or some place

by making you feel slightly less good, lower mood.

I don’t even have to make you feel nauseous,

but less good after ingesting something

or having a certain kind of interaction

or being in a certain environment.

Very straightforward to do that

because of the way that your nervous system

is wired for conditioning.

However, there’s the positive side of all this,

which is that it’s very straightforward

to reinforce the experience of a given food,

including its taste, but all the context around it,

the container, the texture,

the people you consume it with,

where you consume it, et cetera.

For instance, I wonder why we are not pairing caffeine

with broccoli.

And here, I’m not suggesting

that people actually do that experiment

or play that trick on people.

But you have to sort of imagine

that if caffeine is this incredible reinforcer

of all sorts of things,

in particular things that we ingest

and would want to ingest more of

if it’s paired with caffeine,

well, then you actually can use caffeine

as a tool to increase reinforcement of different things.

And you can avoid caffeine

as a way to further reinforce things

that you would like to stop.

And here, I’d like to just give the example

of sugar cravings.

A lot of people ask me,

how do I avoid sugar cravings?

I’ve talked about the use of L-glutamine for that.

I’ve talked about making sure you’re getting enough

essential fatty acids and essential amino acids

as a way to reduce sugar cravings.

Please note, however,

that if you are somebody who likes to have your sugar,

whether or not it’s a piece of chocolate

or your dessert, et cetera,

I’m not saying that’s bad,

but if you’re trying to reduce your sugar cravings,

ask yourself, are you ingesting sugar along with caffeine?

Could be the caffeine contained

in that sugar-containing food like chocolate,

or it could be that you’re having a cup of coffee

along with your pastry,

and then you’re struggling with sugar cravings.

Well, think about it.

You’re not just being reinforced by the sugar

and the effects of sugar on dopamine,

which are real and both conscious and subconscious

through the gut-to-the-brain dopamine system

and direct-on-the-brain dopamine system,

but by co-ingesting caffeine,

you are also further enhancing

the reinforcing effects of sugar.

The flip side to all of this is that you could use caffeine

as a way to increase your appetite for certain things.

I actually know somebody,

I won’t reveal who this person is,

but they are quite prominent podcaster

who ingests 125 to 150 milligrams of caffeine

in tablet form, in tablet form,

along with herbal tea and use this as a way

to develop a preference for herbal tea

because they found that coffee was giving them other effects

that weren’t good for them.

So it works quite well in animals,

and it works quite well in insects,

and it works quite well in humans.

I suppose animals, insects, and humans

are all animals at the end of the day,

so no surprise there,

but it all underscores the extent

to which caffeine is an absolutely fascinating molecule.

I mean, it’s an ability to offset the sleepiness system,

if you will, this adenosine system,

and to control our schedules in that way,

to essentially take a withdrawal against the bank

that is adenosine and then pay that back later

in the form of getting sleepy later

as opposed to when we want to be alert.

It’s ability to enhance focus, alertness, and mood,

and if taken after trying to learn something

and remember it to enhance memory especially,

and its ability to increase VO2 max, increase strength.

We didn’t even talk today about it,

but I’ll just briefly mention that caffeine ingested

in the sorts of doses we talked about earlier

because its effects on the neuromuscular system

and the calcium system associated

with neuromuscular exertion and fatigue

can increase peak power output and muscle contractibility.

So it’s enhancing performance there as well.

And of course, caffeine does a number of other things

just generally related to our overall

and basal level of mood and alertness,

not the least of which are these increases in dopamine.

So caffeine is really an incredible molecule.

It’s affecting all these various neurotransmitter systems,

but not haphazardly.

It’s increasing dopamine and acetylcholine

in the forebrain to increase attention.

It’s reducing fatigue.

It’s improving mental and physical performance

for some obvious and some not so obvious reasons.

And what I think is among the more miraculous

and powerful effects of caffeine,

it is a potent, potent, potent reinforcer

of things, foods, people, and experiences.

And it’s one that you can leverage

in any direction that you like

once you understand the way that caffeine

exerts those reinforcing properties.

So today I’ve really tried to cover as much as I could

about the mechanisms of caffeine action

in the brain and body,

as well as tools and schedules and dosages

in which you can leverage caffeine

in order to meet your physical performance,

mental performance, and frankly,

mental health and overall health goals.

If you’re learning from and are enjoying this podcast,

please subscribe to our YouTube channel.

That’s a terrific zero cost way to support us.

In addition, please subscribe to the podcast

on both Spotify and Apple.

And on both Spotify and Apple,

you can leave us up to a five-star review.

If you have questions for us or comments about the podcast

or guests that you’d like me to interview

on the Huberman Lab podcast,

please put those in the comment section on YouTube.

We do read all the comments.

In addition, please check out the sponsors

mentioned at the beginning and throughout today’s episode.

That’s the best way to support this podcast.

If you’re not already following Huberman Lab

on social media, we are Huberman Lab on all platforms.

So that’s Instagram, Twitter, LinkedIn, and Facebook.

And all of those places,

I describe science and science-related tools,

some of which overlap with the contents

of the Huberman Lab podcast,

but much of which is distinct from content

on the Huberman Lab podcast.

So again, it’s Huberman Lab on all social media platforms.

During today’s episode and on many previous episodes

of the Huberman Lab podcast, we discuss supplements.

While supplements aren’t necessary for everybody,

many people derive tremendous benefit from them

for things like sleep, hormone augmentation, and focus.

If you’d like to see the supplements discussed

on various episodes of the Huberman Lab podcast,

please go to livemomentous.com slash Huberman.

We partnered with Momentous

because they are extremely high quality,

they ship internationally,

and they formulated supplements in the precise ways

that are discussed as optimal to take

for various outcomes here on the Huberman Lab podcast.

If you haven’t already subscribed

to the Huberman Lab podcast newsletter,

it is a monthly newsletter that includes summaries

of podcast episodes, as well as toolkits,

all of which are completely zero cost.

All you have to do is provide your email to sign up.

We do not share your email with anybody.

You do this by going to HubermanLab.com,

go to the menu and tab down to newsletter,

provide your email, you’ll get a confirmation link,

click on that link

and you’ll receive our monthly newsletters.

And you can also access any of the previous newsletters

that we’ve released, including the toolkit for sleep,

for fitness, deliberate cold exposure, and so on,

by going to HubermanLab.com, going to the menu,

going to newsletter, and there you’ll see those

as immediately downloadable PDFs.

Thank you for joining me for today’s discussion

about caffeine, both its mechanisms

and its many powerful uses.

And last, but certainly not least,

thank you for your interest in science.

Thank you.