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’s podcast episode is all about sleep.

We’re also going to talk about the mirror image of sleep,

which is wakefulness.

Now, these two phases of our life, sleep and wakefulness,

govern everything about our mental and physical health.

And we’re not just going to talk about

what’s useful about sleep.

We’re also going to talk about

how to get better at sleeping,

and that will include how to get better at falling asleep,

timing your sleep, and accessing better sleep quality.

In doing so, we’re also going to discuss

how to get more focused and alert in wakefulness.

So because sleep and wakefulness are related,

we really can’t have a conversation

about one without the other.

Now, in keeping with this theme,

you may catch a few snores in the background.

Unlike me, my bulldog Costello

can fall asleep anywhere, anytime,

and he happens to be sleeping over there in the corner.

So if you hear snoring, that’s what that’s about.

As always, I want to just mention that this podcast

is part of my effort to bring zero cost to consumer

public education about science and science-related tools.

It is unrelated to my teaching and research roles

at Stanford School of Medicine.

Our first sponsor is Athletic Greens.

Athletic Greens is an all-in-one

vitamin mineral probiotic drink.

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 twice a day is that it helps me cover

all of my basic nutritional needs.

It makes up for any deficiencies that I might have.

In addition, it has probiotics,

which are vital for microbiome health.

I’ve done a couple of episodes now

on the so-called gut microbiome

and the ways in which the microbiome interacts

with your immune system, with your brain to regulate mood,

and essentially with every biological system

relevant to health throughout your brain and body.

With Athletic Greens, I get the vitamins I need,

the minerals I need, and the probiotics

to support my microbiome.

If you’d like to try Athletic Greens,

you can go to athleticgreens.com slash Huberman

and claim a special offer.

They’ll give you five free travel packs,

plus a year supply of vitamin D3K2.

There are a ton of data now showing that vitamin D3

is essential for various aspects

of our brain and body health.

Even if we’re getting a lot of sunshine,

many of us are still deficient in vitamin D3.

And K2 is also important because it regulates things

like cardiovascular function, calcium in the body,

and so on.

Again, go to athleticgreens.com slash Huberman

to claim the special offer of the five free travel packs

and the year supply of vitamin D3K2.

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

Element is an electrolyte drink that has everything

you need and nothing you don’t.

That means the exact ratios of electrolytes are in Element,

and those are sodium, magnesium, and potassium,

but it has no sugar.

I’ve talked many times before on this podcast

about the key role of hydration and electrolytes

for nerve cell function, neuron function,

as well as the function of all the cells

and all the tissues and organ systems of the body.

If we have sodium, magnesium, and potassium

present in the proper ratios,

all of those cells function properly,

and all our bodily systems can be optimized.

If the electrolytes are not present,

and if hydration is low,

we simply can’t think as well as we would otherwise,

our mood is off, hormone systems go off,

our ability to get into physical action,

to engage in endurance and strength,

and all sorts of other things is diminished.

So with Element, you can make sure

that you’re staying on top of your hydration

and that you’re getting the proper ratios of electrolytes.

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

that’s lmnt.com slash Huberman,

and you’ll get a free Element sample pack

with your purchase.

They’re all delicious.

So again, if you want to try Element,

you can go to elementlmnt.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.

So let’s talk about sleep.

Sleep is this incredible period of our lives

where we are not conscious.

We might dream, we might twitch, we might even wake up,

but in sleep, we are only in relation

to things that are happening within our brain and body.

Outside sensory experience,

in most cases, can’t really impact us.

And yet sleep is this tremendously important period of life

because it resets our ability to be focused,

alert, and emotionally stable in the wakeful period.

So we can’t really talk about wakefulness,

focus, motivation, mood, wellbeing,

without thinking about sleep.

And that’s why we’re devoting this entire month

to the discussion about sleep.

But we also can’t talk about sleep and think about sleep

without thinking about wakefulness,

because it turns out that the period that we call sleep

and the period we call wakefulness

are tethered to one another.

What we do in the waking state determines

when we fall asleep, how quickly we fall asleep,

whether or not we stay asleep,

and how we feel when we wake up the next day.

And today, we’re gonna talk mostly

about how to get better at sleeping.

And the reason for starting the conversation that way,

as opposed to just diving into a lot of biology about sleep,

is because, first of all,

there’s a lot of information out there already

about the biology of sleep.

We’re gonna touch on a little bit of this,

things like stages of sleep and sleep spindles,

melatonin, and dreaming.

But I think that by now, most people are aware

that getting a really good night’s sleep

on a consistent basis is critically important.

But most people don’t know how to do that.

In fact, I’m guessing that very few of you out there

are consistently getting seven to nine hours

of really terrific sleep, waking up feeling rested,

like you’re ready to attack the day,

and being able to go through the day feeling focused

and alert without dips in energy or focus.

So if you’re like most people, which includes me,

you have some challenges with sleep,

at least every third or fifth night or so,

and maybe even more often.

So we’re really gonna go tool heavy today

and talk about tools that can help you fall asleep,

sleep better, and emerge from sleep feeling more rested.

And we’re gonna do that by grounding our discussion of tools

in peer-reviewed studies, mostly from the last 10 years,

although some even more recent than that.

And we’re gonna start by discussing what is sleep

and what governs the timing of the onset of sleep.

In other words, what makes you get sleepy

at a particular time of day?

So what determines how well we sleep

and the quality of our wakeful state?

Turns out that’s governed by two forces.

The first force is a chemical force.

It’s called adenosine.

Adenosine is a molecule in our nervous system and body

that builds up the longer we are awake.

So if you’ve just slept for eight or nine or 10

really deep restful hours,

adenosine is gonna be very low in your brain and body.

If however, you’ve been awake for 10, 15 or more hours,

adenosine levels are going to be much higher.

Adenosine creates a sort of sleep drive or a sleep hunger.

And actually hunger is the appropriate word here

because for most of what we’re gonna discuss today,

we can think of it in an analogous way to nutrition.

Your nutrition and how well you feel

after you eat certain foods,

your overall level of fitness and your cellular health

and your heart health isn’t governed by any one food item

that you might eat or not eat.

It’s governed by a number of different factors.

How often you eat, how much you eat,

which items you eat, et cetera,

and what works best for you.

In the same way, your sleep and your wakefulness

are the product of kind of the average

of a number of different behaviors.

How long you’ve been awake is a key one

because of this molecule adenosine.

So the reason you get sleepy when you’ve been up for a while

is because adenosine is creeping up steadily

the longer you’ve been awake.

And a good way to remember this and think about adenosine

is to think about caffeine.

Caffeine for most people,

except a very small percentage of people, wakes them up.

It makes them feel more alert.

In fact, some people are so sensitive to caffeine

that they feel jittery if they drink it

even in small amounts.

Other people can drink large amounts of caffeine

and not feel jittery at all.

Caffeine acts as an adenosine antagonist.

What that means is that when you ingest caffeine,

whether or not it’s coffee or soda or tea

or in any other form, it binds to the adenosine receptor.

It sort of parks there,

just like a car would park in a given parking slot.

And therefore, adenosine can’t park in that slot.

Now, when caffeine parks in the adenosine receptor slot,

nothing really happens downstream of that receptor.

The receptor can’t engage the normal cellular functions

of making that cell and you feel sleepy.

So the reason caffeine wakes you up

is because it blocks the sleepiness receptor.

It blocks the sleepy signal.

And this is why when that caffeine wears off,

adenosine will bind to that receptor,

sometimes with even greater, what we call affinity,

and you feel the crash.

You feel especially tired.

Now, I’m not here to demonize caffeine.

I love caffeine.

I drink it in the morning and I drink it in the afternoon,

but I’m one of these people that either

because of my tolerance or because of some genetic variations

that exist among people

in terms of their adenosine receptors,

I can drink caffeine as late as four or 5 p.m.

in the evening and still fall asleep just fine.

Some people can’t have any caffeine at all

or can’t have any caffeine past 11 a.m.

or else their sleep is totally disrupted.

All of this has to do with the relationship

between adenosine and these adenosine receptors,

genetic variation,

things that are very hard to find out except experimentally,

meaning each of you needs to decide

and figure out for yourselves

whether or not you can tolerate caffeine

and at what times of day you can tolerate caffeine

in order to still fall asleep easily and get good sleep.

So rather than demonize caffeine

or say that everyone can drink caffeine until late,

you need to figure out what’s right for you.

Caffeine has a lot of health benefits.

It also for some people can be problematic for health.

It can raise blood pressure, et cetera.

Caffeine increases this molecule

that’s a neuromodulator that we call dopamine.

We discussed this in episode one,

which tends to make us feel good,

motivated and give us energy

because as you may have learned in episode one,

dopamine is related to another neuromodulator

called epinephrine, which gives us energy.

In fact, epinephrine is made from dopamine.

So let’s just take a step back

and think about what we’re talking about

when we’re talking about sleepiness.

Sleepiness is driven by increases in adenosine

that happen naturally.

Caffeine prevents the adenosine

from having its action of making us sleepy

by blocking that receptor.

So it gives us energy and it increases our dopamine levels,

but some people can’t tolerate caffeine very well.

Other people can tolerate it just fine.

So you need to determine that experimentally.

All the data say there’s tremendous variation.

And right now, the only way that I’m aware of

for you to decide whether or not

caffeine is a good or a bad thing for you

and whether or not you should ingest it

at a given time of day or at all

is really to figure that out on your own.

In fact, there’s a small subset of people

that can drink caffeine until very late

and they have no trouble falling asleep

because they actually have a mutant form

of the adenosine receptor.

So in keeping with the theme of science

and science-related tools,

this is one of those cases where I can’t give you

a one-size-fits-all prescription,

except to say you need to experiment with caffeine

in a way that’s safe for you and explore that

and figure out what works for you and then stick with that.

Okay, so adenosine is driving the sleep hunger.

When adenosine is low, it’s like we’re well-fed,

we’re not very hungry.

And when adenosine is high,

it’s like we’re fasted for a long time

and we tend to be very hungry.

So when adenosine is high, we really want to fall asleep.

If you want, I’m not suggesting you do this experiment,

but you can do it.

You can stay up for four more hours

than you’re used to staying up

and you’ll find that you’re very, very sleepy.

That’s because adenosine is building up

at levels higher and higher

because you’ve been awake for those extra four hours.

However, if you’ve ever pulled an all-nighter,

you’ll notice something interesting.

As morning rolls around,

you’ll suddenly feel an increase in your energy

and alertness again,

even though adenosine has been building up

for the entire night.

Why is that?

The reason that is is because there’s a second force

which is governing when you sleep and when you’re awake.

And that force is a so-called circadian force.

Circadian means about a day or about 24 hours.

And inside all of us is a clock

that exists in your brain and my brain

and the brain of every animal that we’re aware of

that determines when we want to be sleepy

and when we want to be awake.

Just think about it.

We don’t go through the day

wanting to fall asleep every 30 minutes

and then feeling like we’re wide awake.

Our sleep and our period of sleepiness

tends to be condensed into one block,

typically one six to 10 hour block,

although there’s also variation

in terms of how much people want to sleep.

And we’re going to discuss

how you can diagnose your absolute sleep need

as well as how to recover sleep that you’ve lost.

That block of sleep and when it falls

within each 24 hour cycle

is governed by a number of different things.

But the most powerful thing that’s governing

when you want to be asleep

and when you want to be awake is light.

And in particular, it’s governed by sunlight.

Now I can’t emphasize enough how important

and how actionable this relationship is

between light and when you want to sleep.

It’s quite simple on the face of it,

and it’s quite simple to resolve,

but people tend to make a big mess

of this whole circadian literature, frankly.

So let’s just break it down from the standpoint

of what’s going on in your brain and body

as you go through one 24 hour day.

Let’s start with waking.

So regardless of how well you slept at night

or whether or not you were up all night,

most people tend to wake up sometime

around when the sun rises,

maybe not right at sunrise,

but within an hour or two or maybe three of sunrise.

And I realize there are night shift workers

and there are people traveling and experiencing jet lag

where this is not going to be the case.

We are going to deal with jet lag and shift work

at the end of this podcast.

But for most people, we tend to wake up

about the time that the sun is rising or so.

And as we do that, adenosine levels tend to be low

if we’ve been asleep for reasons that you now understand.

And our system generates an internal signal

that is in the form of a hormone.

Now I’ve talked a lot about neuromodulators

and neurotransmitters.

I haven’t talked a lot about hormones yet on this podcast.

The definition of a hormone is it’s a substance,

a chemical that’s released from one organ in your body

that goes and acts on other organs elsewhere in your body,

including your nervous system.

When you wake up in the morning,

you wake up because a particular hormone called cortisol

is released from your adrenal glands.

Your adrenal glands sit right above your kidneys

and there’s a little pulse of cortisol.

There’s also a pulse of some, and when I say a pulse,

I just mean that the release of a little bit.

There’s also a pulse of epinephrine,

which is adrenaline from your adrenals

and also in your brain and you feel awake.

Now that pulse of cortisol and adrenaline and epinephrine

might come from your alarm clock.

It might come from you naturally waking up,

but it tends to alert your whole system in your body

that it’s time to increase your heart rate.

It’s time to start tensing your muscles.

It’s time to start moving about.

It’s very important that that cortisol pulse

come early in the day,

or at least early in your period of wakefulness.

I say that because some people are waking up at 8 p.m.

and are sleeping all day,

but it’s very important that that pulse of cortisol

occur early in the day

and that it happens all at once.

It sort of sets a rising tide of cortisol in your system.

Now, many of you have probably heard about cortisol

in relation to stress.

And indeed, as we go through our day and our life,

different stressors, different events happen in our life

that make us feel more alert.

Some of the more stressful ones

might be looking at your credit card bill

and seeing what seems to be a fraudulent charge,

or looking at your phone and suddenly seeing a text

that something you thought was going to happen

at a particular time is not going to happen

or you’re running late.

Those will tend to increase norepinephrine and epinephrine,

an adrenaline in your system.

And if they’re severe enough,

you’ll start getting some pulses of cortisol

released from your adrenals throughout the day.

But there’s this normal, healthy rising tide of cortisol

that happens early in the day.

And I say healthy because it wakes you up.

It makes you feel alert.

It makes you feel able to move and wanting to move

and to go out your day for work, for exercise, for school,

for social relations, et cetera.

So when you wake up in the morning

is when that cortisol pulse takes off

and something else important happens.

A timer is set in your body and in your nervous system

that dictates when a different hormone called melatonin,

which makes you sleepy,

will be secreted from a particular brain region.

So let’s talk about that.

When you wake up in the morning

and you experience that rise in cortisol,

there’s a timer that starts going,

and these are cellular timers,

and they’re dictated by the relation

between different organs in your body

that says to your brain and body

that in about 12 to 14 hours, a different hormone,

this hormone we’re calling melatonin,

will be released from your pineal gland.

So there’s two mechanisms here,

a wakefulness signal and a sleepiness signal.

And the wakefulness signal triggers the onset of the timer

for the sleepiness signal.

Now that sleepiness signal that we call melatonin

that’s released from the pineal comes only from the pineal.

Unless you’re taking exogenous melatonin,

you’re supplementing with melatonin,

the only source of melatonin in your body

is going to be this pineal gland.

So let’s talk about the pineal gland for a second.

The pineal gland is a gland that sits

kind of in the little structure

near it for the aficionados out there.

It’s kind of near the fourth ventricle.

It’s about the size of a pea.

Descartes, the philosopher,

said that the pineal was the seat of the soul.

He said that because it’s one of the few structures

in the human brain that there’s only one of them.

You know, most structures,

there’s one on either side of the brain,

so-called bi-hemispheric, but the pineal, there’s only one.

I don’t know anything about souls, really.

Certainly not the science of souls,

but I think it’s very unlikely

that the pineal is the seat of the soul,

but it is a very interesting organ

because it’s the only organ in our body

that releases melatonin,

and that melatonin makes us sleepy and lets us fall asleep.

Now, I’m guessing that many of you are probably asking,

should I take melatonin?

My personal bias on this is, except in rare cases, no,

for the following reason.

Melatonin has a second function,

which is that melatonin also suppresses

the onset of puberty.

In kids, and especially in babies,

melatonin isn’t just released in the evening,

12 to 16 hours after we wake.

Melatonin is released chronically or tonically

throughout the day and night,

and that chronic or tonic release of melatonin

is known to suppress some of the other hormones

in other regions of the brain

that trigger the onset of puberty.

Now, if you or your child has been taking melatonin,

don’t freak out.

As always, any kind of supplement

or anything that you’re going to take

or think about taking,

you really need to consult with your doctor.

I’ve said this many times on this podcast

and it’s in the show notes, et cetera.

But before you remove anything

or add anything to what you’re already doing,

please do consult with a healthcare professional.

However, melatonin is known

to suppress the onset of puberty,

so much so that regular cyclic,

cycled periods of melatonin release from the pineal

really correlate with the onset of puberty

and early adulthood,

meaning as we start secreting melatonin only at night,

that’s also when we tend to transition out of puberty.

Now, there are a lot of things

that correlate in our nervous system,

so it doesn’t necessarily mean it controls it,

but in this case, we know based on lots of data,

endocrinology and so forth,

that melatonin suppresses the onset of puberty.

So supplementing melatonin could be problematic

for that reason,

but if you’ve already gone through puberty,

it could also have some impact

on other hormone systems in your body.

So that’s why I personally don’t like

to use melatonin to fall asleep.

There’s another reason,

which is that melatonin will help you fall asleep,

but it won’t help you stay asleep.

And many people who take melatonin

find that they wake up three to five hours later

unable to fall back asleep.

Part of the reason for that might be

that melatonin purchased,

you can buy it over the counter in most areas of the world,

even though it’s a hormone, which is a little unusual,

you can’t just go into a pharmacy,

at least in the U.S. and buy testosterone

or cortisol or estrogen,

you need a prescription,

but you can go buy melatonin for whatever reason.

I don’t know the reasons for that legality,

but it’s been shown many times.

And now I’m borrowing from some items

that were in Matt Walker’s book,

Why We Sleep,

where he stated there is evidence

that in commercially available melatonin,

the amount of melatonin has been tested for various brands,

and it can range anywhere from being 15%

of what’s listed on the bottle,

so if they list this as a hundred milligrams

would be a tremendously high dose,

it turns out it’s only 15 milligrams

in that particular pill or capsule,

or up to 400 times more than what’s listed on the bottle.

So it’s completely unregulated.

And so for those of you taking melatonin,

I will discuss at the end of the podcast,

some other potential alternatives that are probably safer

and don’t have these issues.

So should you take melatonin?

My personal bias is no,

but for many people they find that it does help them,

and so if you do find it helps you,

then just consider what I’m saying

in light of the other practices that you’re doing

and talk to your healthcare professional.

Okay, so the rhythm of cortisol and melatonin

is what we call endogenous.

It’s happening in us all the time

without any external input.

In fact, if we were in complete darkness,

living in a cave with no artificial lights whatsoever,

or we were in complete brightness

where we never experienced any darkness,

these rhythms of cortisol and melatonin would continue.

You would have a bump in cortisol or a pulse in cortisol

that would drop off with time,

and then melatonin would come up

about 12 to 14 hours later.

But these endogenous systems of our body,

which are both hormonal and neural,

were set so that external things

could govern when they happen.

Now, this takes us back to episode one of the podcast

that if you haven’t listened to already,

you might want to listen to,

where we talked about sensation and perception and all that.

I’m not going to review it again here,

but there’s one particular sensory event,

one particular influence on your nervous system

that determines when that cortisol

is going to start to rise.

So if you were in complete darkness,

it would happen once per 24-hour cycle,

but it would be somewhat later and later each day.

Whereas under normal circumstances,

what happens is you wake up,

and what happens when you wake up?

You open your eyes.

When you open your eyes, light comes into your eyes.

Now, the way this system works

is that you have a particular set of neurons in your eye.

They’re called retinal ganglion cells.

You don’t have to remember that if you don’t want to,

but these retinal ganglion cells are brain neurons.

Again, the retina is just the one piece of your brain,

actually two pieces,

because most of you have two retinas,

that resides outside the skull per se.

When light comes into the eye,

there’s a particular group of retinal ganglion cells

or type of retinal ganglion cells

that perceives a particular type of light

and communicates that to this clock

that resides right above the roof of your mouth

called the suprachiasmatic nucleus, okay?

So I know this can get a little complicated,

but these retinal ganglion cells,

when you open your eyes, light comes in,

and an electrical signal is sent to this central clock,

we call the suprachiasmatic nucleus.

And the suprachiasmatic nucleus has connections

with essentially every cell and organ of your body.

Now, it’s vitally important

that we get light communicated to the central clock

in order to time the cortisol and melatonin properly.

When I say properly, I can say that with confidence,

because we know based on a lot of evidence

that if you don’t get your cortisol

and melatonin rhythms right,

there are tremendously broad and bad effects

on cardiovascular health, dementia, metabolic effects,

learning, depression, dementia.

In fact, there’s so many negative effects

associated with getting this wrong

that I don’t want to go into it in too much detail.

In fact, I feel like we’ve been bombarded

with all this information about how we’re not sleeping well,

we’re not sleeping at the right times,

we’re not sleeping enough,

to the point where people now have sleep anxiety.

They can’t sleep well for a night,

they’re feeling overwhelmed by that,

and it’s sort of now they’re stressed

about not being able to sleep,

which is making it harder to sleep, et cetera.

I really want to focus on what we can do

to anchor these systems properly.

So let’s think about what happens when we do this correctly

and how to do it correctly.

When we wake up, our eyes open.

Now, if we’re in a dark room,

there isn’t enough light to trigger the correct timing

of this cortisol melatonin thing, these rhythms.

You might say, well, why won’t any light do it?

Well, it turns out that these neurons in our eye

that set the circadian clock

and then allow our circadian clock

to set all the clocks of all the cells and organs

and tissues of our body,

responds best to a particular quality of light

and amount of light.

And those are the qualities of light

and amount of light that come from sunlight.

So these neurons, what they’re really looking for,

although they don’t have a mind of their own,

is the sun at what we call low solar angle.

The eye and the nervous system

don’t know anything about sunrises or sunsets.

It only knows the quality of light that comes in

when the sun is low in the sky.

This system evolved so that when the sun is low in the sky,

there’s a particular contrast between yellows and blues

that triggers the activation of these cells.

So if you wake up and you look at your phone

or your computer,

or you flip on a bunch of artificial lights,

will these cells be activated?

And the answer is sort of.

They’ll be activated, but not in the optimal way.

What you want to do is get sunlight in your eyes

as close to waking as possible.

Now, I want to be really clear about this

because I’ve talked about it on other podcasts

when I was a guest,

and I’ve talked about it on my Instagram feed,

and there seemed to be the same questions

coming up again and again.

These neurons don’t know sunlight per se.

They don’t know sunrise or sunset for that matter.

They don’t know artificial light from sunlight.

What they respond best to, however,

is the quality and amount of light that comes in

when the sun is low in the sky.

That means that if you can watch the sunrise, great.

That’s perfect for triggering activation of these cells.

However, if you wake up a few hours after the sunrise,

which I tend to most days personally,

you still want to get outside and view sunlight.

You don’t need the sunlight beaming you

directly in the eyes.

There’s a lot of photons, light energy,

that’s scattered from sunlight at this time.

But the key is to get that light energy from sunlight,

ideally, into your eyes.

Now, I know many of you are already asking,

well, I live in Scandinavia or I can’t get sunlight.

There’s buildings around me, et cetera.

We will get to all of that.

But it’s critically important that you get outside

to get this light.

I had a discussion with a colleague of mine,

Dr. Jamie Zeitzer,

who’s in the Department of Psychiatry

and Behavioral Sciences at Stanford,

a world expert in this.

And he tells me that it’s 50 times less effective

to view this sunlight through a window,

through a car windshield,

or through a side window of a car,

than it is to just get outside with no sunglasses

and view light early in the day.

Now, if you can’t see the sunrise, like I said,

you can see this within an hour or two of sunrise,

but it has to be low solar angle.

Once the sun is overhead, the quality of light shifts

so that you miss this opportunity

to time the cortisol pulse.

And that turns out to be a bad thing to do.

You really want to time that cortisol pulse properly

because, we’ll get into this a little bit more later,

but a late shifted cortisol pulse,

in particular in 9 p.m. or 8 p.m. increase in cortisol,

is one of the consequences,

and maybe one of the causes

of a lot of anxiety disorders and depression.

So it’s kind of a chicken egg thing.

We don’t know whether or not it’s the correlated with,

it’s the cause or the effect,

but it’s a signature of depression and anxiety disorder.

Bringing that cortisol pulse earlier

in your wakeful period, earlier in your day,

has positive benefits,

ranging from blood pressure to mental health, et cetera.

I’m not going to list them all off

because there’s just so many of them,

but many, many positive things happen

when you are getting the cortisol early in the day,

far away from your melatonin pulse.

So how long should you be outside?

Well, this is going to vary tremendously

because some people live in environments

where it’s very bright.

So let’s say it’s Colorado in the middle of winter,

there’s a snow field,

there’s no cloud cover and you walk outside,

there’s going to be so much photon light energy

arriving on your retina,

that probably only takes 30 to 60 seconds

to trigger the central clock

and set your cortisol and melatonin rhythms properly

and get everything lined up nicely.

Whereas if you’re in Scandinavia in the depths of winter

and you wake up at 5 a.m.

and the sun is just barely creeping across the horizon

then goes back down again a few hours later,

you probably are not getting enough sunlight

in order to set these rhythms.

So many people find that they need to use

sunlight simulators in the form of particular lights

that were designed to simulate sunlight.

However, I’m not out to attack the companies

that produce those.

There’s another solution to that.

You can simply go outside for longer.

Even if there’s a lot of dense cloud cover,

you’re probably getting anywhere from 10,000

to 50,000 lux LUX, which is just a measure of light energy.

And that should be sufficient to set the circadian clock.

You could say, well, the lights in my house or my phone

are really, really bright, right?

Everyone’s telling us to stay off our phones at night

because they’re really bright.

But guess what?

It turns out that early in the day,

your retina is not very sensitive,

which means you need a lot of photons,

ideally coming from sunlight to set these clock mechanisms.

So looking at your phone or artificial lights is fine

if you wake up before sunrise,

but it’s not going to work to set these clock mechanisms.

And this is supported by dozens,

if not hundreds of quality peer reviewed studies.

So you want to use sunlight.

If you can’t see sunlight because of your environment,

then you are going to have to opt for artificial light.

And in that case, you’re going to want an artificial light

that either simulate sunlight or has a lot of blue light.

Now, without going off course here,

you might be saying,

wait, I’ve heard blue light is bad for me.

Actually, blue light is great for this mechanism

during the day.

We can talk about blue light and blue blockers,

but you really want a lot of blue and yellow light

arriving on the retina early in the day.

Let me be clear about something.

You never ever want to look at any light,

sunlight or artificial light that is painful to look at.

If you find that your eyes are watering

or you’re having challenges maintaining,

looking at this thing for a while because it’s painful,

that light is too bright

and you do not want to damage your retina.

So you don’t want to gaze at the sun,

refusing to blink and burn your retina.

That’s actually possible to do.

You don’t want to do that.

You have a proper blink reflex installed in you since birth.

And if you feel like something’s too bright

and you need to blink,

it means you need to blink,

that it’s too much light.

So please don’t beam your eyes with really bright light.

But blue light, in particular,

blue light and yellow light coming from sunlight is ideal.

If you’re going to get it from artificial light

because you can’t get enough sunlight,

well then, artificial lights that are rich in blue,

blue wavelengths are going to be ideal

for setting this mechanism.

A lot of people will say,

oh, I should be wearing blue blockers throughout the day.

No, that’s the exact wrong thing.

If you’re going to use blue blockers,

we can talk about that.

That should be reserved for late in the evening

because light suppresses melatonin.

I’ve been asked many times before about this pineal gland.

And there are a lot of ancient practices

that map to some of the things that I’m saying.

And people always say,

oh, I heard that sunlight is great for the pineal.

Well, perhaps,

but we have to be careful about that phrase.

Sunlight inhibits the pineal.

It prevents it from releasing melatonin.

Darkness allows the pineal to release melatonin.

So the pineal is not the gland or the organ of sunlight.

It is the gland of darkness.

In fact, melatonin can be thought of as a sleepiness signal

that’s correlated with darkness.

So get up each morning, try and get outside.

I know that can be challenging for people,

but anywhere from two to 10 minutes of sunlight exposure

is going to work well for most people.

And you want to do this on a regular basis

and you don’t have to do it exactly at sunrise.

I realize I’m repeating myself,

but somehow despite barking at people about this

for a couple of years now,

I keep getting the same questions

and somehow it hasn’t been sinking in,

which could be related to some circadian disorder.

I’m just kidding.

If it’s not sinking in,

it’s probably that I’m not being effective

in communicating the information.

But get that bright light early in the day from sunlight.

And if you can’t get it from sunlight,

get it from artificial light.

What kinds of artificial lights will work?

Well, there are these sunrise simulators,

but the ring lights that people use for selfies

and this sort of thing for posting on Instagram,

those generate a lot of blue light.

If you want to get experimental about this,

there’s a free app.

I have no relationship to the app,

but it’s a great app called Light Meter

that you can use your phone

and you can measure the amount of photon energy

in your environment.

And it’s kind of a fun experiment to do.

You can go outside in the morning

and you’ll see that there’s 10,000, 20,000 lux,

even though it might seem like it’s kind of dim

or there’s tree cover or cloud cover.

You go inside and you shine

that artificial light at your phone,

press the button on Light Meter,

and you’ll find that it’s only 500 or 1,000 lux.

And you realize that even though it seems really bright,

the artificial light is very condensed,

whereas the outside light is scattered in the atmosphere.

And so you can think that you’re not getting much sunlight,

but you’re actually getting much more outside.

So get outside, get that sunlight early in the day

and try and do it on a consistent basis.

If you can’t do it every day,

or you sleep through this period of the early day,

low solar angle, don’t worry about it.

The systems in the body,

these hormone systems and neurotransmitter systems

that make you awake at certain periods of the day

and sleepy at other times are operating

by averaging when you view the brightest light.

Now, that can immediately tell us

that what most people are doing is terrible.

They’re waking up and they’re looking at their phone,

which isn’t triggering activation of these cells in the eye

in the central circadian clock.

Then a few hours later,

they might get in their car with sunglasses and drive.

Now, a note about sunglasses and prescription lenses.

Absolutely never, ever, ever compromise safety

for the sorts of things I’m talking about.

So if you need to wear sunglasses for safety reasons,

wear them.

Absolutely, if you wear prescription lenses or contacts,

wear them.

They won’t filter out the wavelengths of light

that are necessary for setting these central clocks.

So safety first, of course.

If you have a retinal degenerative disorder,

retinitis pigmentosa, macular degeneration, or glaucoma,

or those run in your family,

you want to avoid excessively bright light all the time.

You want to be very cautious about that.

You’re going to want to get your light exposure

through seeing dimmer light, including sunlight,

but for longer periods of time, perhaps.

You might immediately ask,

what about low vision or blind people?

How do they set these central clocks?

Well, it turns out that low vision and blind people,

most of them, provided they still have eyes,

that the eyes weren’t removed because of a burn or tumor

or something like that,

still maintain these neurons that set the circadian clock,

which brings me to a really important point.

It’s not about seeing and perceiving the sun.

This is a subconscious mechanism by which these neurons,

which are called melanopsin ganglion cells,

these neurons set your central clocks

by getting activated by the particular wavelengths of light

that are present in the atmosphere,

even coming through cloud cover,

and you don’t need to see or perceive the sun

in order to get this mechanism to start.

Now, it’s such a vitally important mechanism

because it dictates how well and what time

you will want to fall asleep later in the day.

So for those of you that are night owls,

and you insist that you’re a night owl,

and you have the genetic polymorphism

that makes you a night owl,

you may very well have that genetic polymorphism,

those genes that make you want to stay up late

and wake up late.

But chances are about half of you

that think that you’re night owls

are just not getting enough sunlight early in the day.

So viewing light early in the day, ideally sunlight,

is key for establishing healthy sleep-wake rhythms

and for allowing you to fall asleep easily at night.

Now, it’s not gonna make sure

that all that happens every single time,

but it is the foundation of proper sleep

and what we call circadian health.

It governs metabolism and so many other things

that are supposed to exist on a regular 24-hour cycle.

Some of you, many of you might be asking,

what else can help set this rhythm?

Well, it turns out that light

is what we call the primary zeitgeber, the time giver.

But other things can help establish this rhythm

of cortisol followed by melatonin

12 to 16 hours later as well.

The other things besides light are timing of food intake,

timing of exercise, as well as various drugs or chemicals

that one might ingest, not illegal drugs,

although those will impact circadian mechanisms as well.

But the reason we focus so heavily on light

is that light is the main way that the central clock,

the suprachiasmatic nucleus, was supposed to be set.

We know that because it’s the only direct input

to the clock.

These neurons in the eye that are also part of the brain

that we call melanopsin ganglion cells

that not so incidentally were discovered

by my friend and colleague David Burson

at Brown University and others,

Samar Hattar, King Wai Yao, et cetera,

worked out the mechanisms, the molecular mechanisms,

but it was really David Burson

that discovered these incredibly fascinating non,

you know, these are cells that aren’t important for sight

like pattern vision, but are for setting our clocks.

David’s really credited with making that discovery.

Those cells are the main way

and the only direct way to set the clock.

In fact, it’s fair to say that light

viewed by these melanopsin cells, particular sunlight,

is 1,000 to 10,000 times more effective

than say getting up in darkness and just exercising.

That doesn’t mean that you shouldn’t exercise

early in the day in darkness if that’s what you like to do.

It will have somewhat an effect

on raising your wakefulness early in the day

and setting these rhythms.

And this is because of some other pathways.

For the aficionados out there

who want to know more neuroscience, here’s how it goes.

You’ve got this clock above the roof of your mouth

that churns out this 24 hour rhythm

and is communicated to all the other organs

and tissues of your body.

But there’s another structure, has a cool name.

It’s called the intergeniculate leaflet,

which sits a few millimeters away in the brain.

And it’s involved in regulating the clock output

through what’s called non-photic,

non-light type influences like exercise

and feeding, et cetera.

So if you are not feeling awake during the day

and you’re having trouble sleeping,

get the sunlight exposure that we just talked about.

But in addition to that,

if you want to become an early riser, for instance,

and you want to feel more awake

during the early part of the day,

by getting that light exposure

and exercising early in the day,

you will, after two or three days,

you will naturally start to wake up earlier in the day.

And that’s because these clock mechanisms have shifted.

It’s like setting the clock earlier

as opposed to delaying the clock.

And that takes us to a somewhat complicated,

but very important aspect to all this,

which is what sets the clock and keeps it anchored.

The main thing is that bright light early in the day.

The other thing is sunset.

When the sun is also at low solar angle,

low close to the horizon,

by viewing sunlight at that time of day in the evening

or afternoon, depending on what time of year it is

and where you are in the world,

these melanopsin cells, these neurons in your eye

signal the central circadian clock

that it’s the end of the day.

And there’s a really nice study that was published last year

and I will put links to these references on a website

not too long from now.

There was a really nice study that showed

that viewing sunlight around the time of sunset

doesn’t have to be just crossing the horizon,

but circa sunset within an hour or so of sunset

prevents some of the bad effects of light

in preventing melatonin release later that same night.

So let me repeat this.

Viewing light early in the day is key.

Viewing light later in the day when the sun is setting

or around that time can help protect these mechanisms,

your brain and body,

against the negative effects of light later in the day.

So let me talk about how you would do that.

You’d go view the sunset or you would go outside

in the late afternoon or evening.

Again, if you safely can do that with sunglasses off,

you will.

If you need to wear sunglasses, fine,

but it will take probably 100 to 1,000 times longer

with dark sunglasses than if you take them off.

Again, if you want to do this through a window at work,

that’s fine, but it’ll take 50 times longer.

So the best thing to do is just to get outside

for a few minutes,

anywhere from two to 10 minutes also in the afternoon.

Having those two signals arriving to your central clock

that your body, your internal world knows

when it’s morning and knows when it’s evening

is tremendously powerful.

Maybe think about it this way.

Every cell in your body needs glucose and energy.

It needs, whether or not it gets that from meat

or it gets it from ketones

or it gets it from carbohydrates or fruit or vegetables,

doesn’t matter.

It is eventually converted into a certain form of energy

that all your cells use.

But you don’t take glucose,

you don’t take a bread or a steak or a nice orange

and shove it in your ear.

You put it in your mouth, it goes into your stomach,

it’s digested,

and then that resource is distributed

to all the cells of your body.

Every cell in your body needs oxygen

and you don’t put a hose through your nostril

or through your ear

or through some other orifice in your body.

You inhale air and it’s then distributed via the lungs

to the cells in your bloodstream

and that’s distributed to all the organs of your body.

Every cell and organ in your body needs light information.

And the way to get that light information

to all those cells because you have a thick skull

and dark, you know, inside of you is dark inside your skin,

there’s no sunlight getting in there,

is by viewing sunlight with your eyes

at the two times a day that I’m referring to.

Okay, that’s the only route.

There was a study published in Science,

an excellent journal well over 10 years ago

that showed that light shown on the back of the knee

could set these circadian rhythms.

That study was retracted

and unfortunately most people don’t know

that it was retracted.

There were some experimental flaws

that people were actually viewing light through their eyes.

That study was repeated,

turns out there is no extraocular photoreception in humans.

Whatever somebody tells you that light to the skin

or light to the wherever is beneficial for your health,

we can talk about that,

but there’s no way that light information

is setting your clocks.

You need these cells in your eyes to perceive

or to see light at the particular times of day

that I’m referring to.

Some animals like snakes and other reptiles

actually have a hole in the top of their skull

to get light information directly to their pineal

to suppress melatonin.

We don’t have that hole.

I mean, most of you don’t have holes in your skull.

These holes in your skull

that we call the sockets for the eyes

are actually there primarily to allow light information

to the central clock

and then vision and pattern vision and color vision

came much later in evolution.

We know this on the basis of genetic studies

we get to discuss in a future podcast.

So get that light information

to the cells of your brain and body

by viewing sunlight at the two times a day

that I referred to.

There’s always a lot of questions about how long, how much,

how do I know if I’ve had enough?

You’ll know because your rhythm will start to fall

into some degree of normalcy.

You’ll start to wake up at more or less

the same time each day.

You’ll fall asleep more easily at night.

Generally, it takes about two or three days

for these systems to align.

So if you’ve not been doing these behaviors,

it’s going to take a few days,

but they can have tremendous benefits

and sometimes rather quickly on a number of different

mental and physical aspects of your health.

Now let’s talk about the bad effects of light

because light is not supposed to arrive in our system

at any time.

And nowadays, because of screens and artificial light,

we have access to light at times of day and night

that normally we wouldn’t.

Now, earlier I said that you need a lot of light

in particular sunlight to set these clock mechanisms.

That’s true, but there’s a kind of diabolical feature

to the way all this works,

which is the longer you’ve been awake,

the more sensitive your retina and these cells are to light.

So that if you’ve been awake for 10, 12, 14 hours,

it becomes very easy for even a small amount of light

coming from a screen or from an overhead light

to trigger the activation of the clock

and make you feel like you want to stay up later,

make it harder to fall asleep

and disrupt your sleep pattern.

Okay, so the simple way to think about this is

you want as much light as is safely possible

early in the day, morning and throughout the day,

including blue light.

So take those blue blockers off during the day,

unless you have a real issue with screen light sensitivity.

And you want as little light coming into your eyes,

artificial or sunlight, after say 8 p.m.

And certainly you do not want to get bright light exposure

to your eyes between 11 p.m. and 4 a.m.

And here’s why.

David Burson, who I mentioned before,

and another friend and colleague, Samer Hattar,

who’s director of the chronobiology unit

at the National Institutes of Mental Health,

published a paper in Cell, which is a journal,

another excellent journal, very high stringency,

showing that light that arrives to the eyes

between 11 p.m. and 4 a.m. approximately

suppresses the release of dopamine,

this neuromodulator that makes us feel good

as sort of an endogenous antidepressant,

and can inhibit learning

and create all sorts of other detrimental effects.

It does this through a mechanism,

for those of you who want to know the neural pathways,

that involves light to the eyes

that’s then signaled to a structure called the habenula.

The habenula looks like two little bat ears

sitting right in the middle of a structure

in your brain called the thalamus.

Don’t worry about these names

if you’re not interested in this stuff.

If you are, these are just avenues to explore.

When that habenula gets activated,

it’s actually called the disappointment nucleus,

because it actually makes us feel less happy

and more disappointed,

and can lead to certain forms of depression

in the wakeful state.

Now, if you wake up in the middle of the night

and you need to use the bathroom,

or you’re on an all-night flight

and you need to read or whatever it is, fine.

Every once in a while, it’s not going to be a problem

to get bright light exposure to your eyes

in the middle of the night.

But if you think about our lifestyle nowadays

and being up late looking at phones,

even if you dim that screen,

you’re triggering this activation,

because your retinal sensitivity

and the sensitivity of these neurons

has gone up late in the day.

Now, I’m not here to dictate what you should or shouldn’t do,

but for those of you

that are experiencing challenges with mood,

those of you that have anxiety, learning problems,

issues focusing,

the questions I usually get are, how can I focus better?

Well, we will get to that.

But one of the best ways you can support your mechanisms

for good mood, mental health,

learning, focus, metabolism, et cetera,

is to take control of this light exposure behavior at night

and not get much or any bright light exposure

in the middle of the night.

Red light won’t trigger this pathway,

but very few people have the kind of infrared lights

that are set up or floor lights.

And that brings me to an important point,

which is about the location of light.

This hasn’t been discussed much out there, I don’t think.

These cells in our eye, these neurons,

that signal the central clock,

reside mostly, not exclusively,

but mostly in the bottom half of our retina.

And because we have a lens in front of our retina,

and because of the optics of lenses,

that means that these cells

are actually viewing our upper visual field.

There’s an inversion of the visual image, et cetera.

You can look that up

if you want to learn more about retinal optics.

It’s fascinating, but not the topic for today.

These cells are in the bottom half of your retina mostly,

and so they’re viewing the overhead visual space around you.

This is probably not coincidental

that these cells were essentially designed

to detect sunlight, which is overhead, of course.

So if you want to avoid improper activation

of these neurons, it’s better to place lights

that you use in the evening

low in your physical environment,

so on desktops or even the floor,

if you want to go that way,

as opposed to overhead lights.

So overhead fluorescent lights would be the worst.

That would be the worst case scenario.

Lights that are overhead that are a little bit softer

of the sort of yellow or reddish tints

would be slightly better,

but dim lights that are set low in the room

are going to be best

because they aren’t going to activate these neurons

and therefore shift your circadian clock.

So that’s a goal.

Some people like Samer Hattar that I mentioned earlier,

he turns his home basically into a cave in the evenings.

Candlelight actually does not trigger activation

of these cells, so candlelight and fireplaces

and campfires are fine.

Dim lights, very dim lights are fine

and lights low in the physical environment.

Of course, the problem with candlelight and fireplaces

is the fire hazard, but you’re smart people,

you know what to do about that.

Don’t burn down whatever structure you’re in,

including forest police.

So keep the lights low in your environment.

What if you wake up in the middle of the night

and you find yourself watching TV or on the computer?

And well, in that case,

you might want to wear blue blockers

and you certainly would want to dim the screen,

but ideally you’re not doing that.

It’s remarkable the positive effects

of getting that bit of sunlight early in the day,

maybe even also around sunset and avoiding bright lights

and especially overhead bright lights

between about 11 p.m. and 4 a.m.

Now I’m not talking about shift work.

I’m realizing that we’re probably going to have to have

an entire discussion devoted just to shift workers

because there’s some good information there

about how they can protect themselves

against some of the very bad health effects of shift work,

of getting light in the middle of the night.

But we rely on shift workers and they’re super important

to culture and society and the economy.

So I want to acknowledge them and let you know

that we will do a discussion about shift work and jet lag.

But let’s talk about what light can do

in terms of shifting us in healthy ways.

So the way to think about this whole system,

again, is you’ve got adenosine building up

depending on how long you’ve been awake

and it’s making you sleepy.

And then you’ve got their circadian mechanisms

that are timing your wakefulness

and timing when you want to be asleep,

mainly through cortisol and melatonin.

But there are a bunch of other things

that are downstream of cortisol and melatonin.

Like we tend to be hungrier during our wakeful period

than late at night.

Some people like to eat it late at night,

but if you’re finding that you can’t become a day person

or a morning person, shifting your light exposure,

exercise and food intake to the daytime will help.

Some people like to stop eating around 6 or 8 p.m.

because of metabolic reasons,

or they’re trying to maintain their weight or lose weight.

That’s actually not supported so well by the literature.

The literature around nutrition essentially says

that it’s best to restrict your feeding

to a certain period of each 24-hour cycle

to not be eating around the clock.

And whether or not that’s four hours or eight hours

or 16 hours is a much lengthier discussion

than we have time for now.

I would refer you to Sachin Panda’s book,

The Circadian Code, which talks all about that.

He’s an expert, a former colleague of mine

from the Salk Institute in San Diego.

You can explore intermittent and circadian fasting,

so to speak, through Sachin’s literature.

We’ll talk about that.

We might even get Sachin in here

if we’re lucky at some point in the future.

But you can actually use light to wake up earlier.

Jamie Zeitzer and colleagues did a beautiful study

showing that if you turn on the lights before waking up,

so around 45 minutes to an hour before waking up,

even if your eyelids are closed,

provided you’re not under the covers,

after doing that for a few days,

that increases your total sleep time

and shifts forward the time at which you feel sleepy.

It makes you want to go to bed earlier each night.

Now, in a kind of a diabolical way,

they did this with teenagers who are notorious

for wanting to wake up late and stay up late.

And what they found was bright light flashes,

just turning on the lights in their environment,

overhead lights,

because they’re trying to activate the system,

and that’s why they’re using overhead lights,

even through the eyelids before these kids woke up,

then made those kids naturally want to go to bed earlier

and they ended up sleeping longer.

So that’s something you could try.

You could put your lights on a timer to go on

early in the day before you wake up.

You could open your blinds so that sunlight is coming

through.

And again, if you curl up under the covers,

then it’s not going to reach these neurons,

but it’s remarkable the light can actually penetrate

the eyelids,

activate these neurons and go to the central clock.

That study illustrates a really important principle

of how you’re built,

which is you have the capacity for what are called

phase advances and phase delays.

And I don’t want to complicate this too much.

So the simplest way to think about phase advances

and phase delays is that if you see light late in the day,

and in particular in the middle of the night,

your brain and body, for reasons that now you understand,

will think that that’s morning light,

even though it’s not sunlight,

because you have this heightened sensitivity

and it will phase delay, will delay your clock.

It will essentially make you want to get up later

and go to sleep later.

So if you get light exposure too late in the evening

or in the middle of the night,

it’s going to make it hard to want to wake up the next

morning early and to go to bed early.

The opposite is also true.

If you wake up early, say, you know,

6 a.m. or 7 a.m. and get light exposure or even earlier,

4 a.m. and get light exposure,

it will phase advance your clock, okay?

It’s going to make your clock think it’s earlier

and you’ll want to wake up earlier.

So the simple way to think about this is if you’re having

trouble waking up early and feeling alert early in the day,

you’re going to want to try and get bright light exposure

even before waking up,

because it will advance your clock.

It will, it’s sort of like turning the clock forward.

Whereas if you are having trouble waking up early,

you definitely don’t want to get too much light exposure

or any light exposure to your eyes late in the evening

and in the middle of the night,

because it’s just going to delay your clock more and more.

So rather than get into the specifics of everybody’s

situation, because there are many of you out there with

different situations and lifestyle requirements, et cetera,

the way to think about this is that you have these internal

mechanisms of adenosine and circadian clocks,

and they’re always operating.

And what you’re trying to do is provide them anchors.

You’re trying to provide them consistent, powerful anchors.

So that your cortisol, your melatonin,

and then everything that’s that cascades down from that,

like your metabolism and your ability to learn and your

sense of alertness, your dopamine, your serotonin,

all that stuff is timed regularly.

One of the reasons why there’s so much, you know,

challenge out there with focus and anxiety and depression,

there are a lot of reasons for that.

But one of the reasons is that people’s internal mechanisms

aren’t anchored to anything regular.

Now this doesn’t require being neurotically attached to

getting up at a very specific time, going outside,

viewing the sunlight same time every day.

These systems again will average,

but if you can provide them consistent light anchors early in

the day and in the evening and avoiding light at night,

you will be amazed at the tremendous number of positive

effects that can come from that at the level of metabolic

factors, hormones, and just general feelings of wellbeing.

In fact, most of us are familiar with what it is to not

sleep well and all the terrible effects that has.

Maybe one night you’re fine,

two nights even for the new parents out there.

I sympathize with you,

but most people are not familiar with what it is to sleep

really, really well on a consistent basis.

And when you start doing that by controlling your sleep

environment, right?

Get the proper sleep surface, get the proper pillow,

get the temperature in the room, right?

Get your light exposure, right?

Start timing your exercise at normal periods or times

throughout the day and week.

It’s amazing how many other biological systems just naturally

fall in line.

And this is why whenever people ask me, what should I take?

Which is one of the most common questions I get,

what supplement should I take?

What drug should I be taking?

What things should I be taking?

The first question I always ask them is how’s your sleep?

And 90% of the time they tell me they either have trouble

falling asleep or staying asleep,

or they don’t feel rested throughout the day.

A brief note about naps.

Naps provided that they’re less than one Ultradian cycle,

provide their 20 minutes or 30 minutes, or even an hour,

can be very beneficial for a lot of people.

You don’t have to take them,

but many people naturally feel a dip in energy and focus

late in the afternoon.

In fact, if we were going to look at wakefulness,

what we would find is that you get that morning light

exposure, hopefully your cortisol goes up,

people start feeling awake.

And then around two or three or four in the afternoon,

there’s a spike in everything from alertness to ability to

learn some metabolic factors drop,

and then it just naturally comes back up.

And then it tapers off as the night goes on.

So for some of you, naps are great.

I love taking naps.

Some people they wake up from naps feeling really groggy.

That’s probably because they’re not sleeping as well as they

should at night or as long as they should at night.

And so they’re dropping into REM sleep or deeper forms of

sleep in the daytime.

And then they wake up and they feel kind of disoriented.

Other people feel great after a nap.

So that’s another case where just like with caffeine,

you sort of have to evaluate for yourself.

As we discuss this,

you’re probably realizing this is a lot like nutrition where

nowadays it’s just crazy.

I mean, if you go on social media,

it’s like you’ve got people who are pushing carnivore,

you got other people who are pushing vegan,

other people who are pushing, you know, paleo,

every variation of every diet.

And there’s a lot of data to support any and all of those.

And the arguments go on and on.

And there’s probably a lot of genetic variation and

lifestyle variation that’s going to dictate whether or not

something is good for you, whether or not you like it,

whether or not you’ll stick to it.

The same thing is true for circadian and sleep and

wakefulness behaviors,

except the light viewing behavior that I talked about

before, there’s no way around that.

That’s hardwired into our system.

The same way we could factually say that everybody needs

some nutrition at some level from some source,

everybody needs light information arriving in their system in

some way at regular intervals.

So that’s really what this is about.

Okay, so naps are going to be good for some people,

not for others.

I have a colleague,

a very accomplished neuroscientist who likes to take naps

just after lunch.

I personally like to take a nap around three or 4 p.m.,

but there’s a practice that I’ve adopted in the last five

years that I’ve found to be immensely beneficial.

That is sort of like napping, but isn’t napping.

It’s a thing that they call yoga nidra.

Yoga nidra actually means yoga sleep.

And it’s a sort of meditation that you listen to.

There are a number of scripts.

I’ve talked about this on podcasts before,

but I’m going to post a link to the two that I like most,

that allows you to consciously bring your entire body and

mind into a state of deep relaxation.

And sometimes you fall asleep and sometimes you don’t.

This is done for 10 to 30 or even 60 minutes at a time.

The other thing that works really well is meditation.

So I’m talking about naps,

but I’m also talking about yoga nidra,

which is sort of a form of meditation and then more standard

forms of meditation.

All three of those do something powerful,

which is that they bring our mind into a state of less so

called sympathetic nervous system activation.

Go back and listen to episode one,

if that doesn’t make any sense,

which is what governs your alertness.

And instead it activates cells and circuits in your body that

promote the parasympathetic nervous system or the calming

system.

A lot of people are not good at falling asleep because

they’re not good at calming down.

So some people have no trouble falling asleep,

but many people have a hard time falling asleep,

or at least every once in a while experience challenges

falling asleep.

I don’t have problems falling asleep most nights,

but I’ve noticed that if I’m working very hard or if the

world is particularly stressful,

my mind gets into a bit of a kind of OCD loop where I tend

to ruminate on things.

And I’m not even thinking about anything in particular.

It’s just challenging for me to disengage and fall asleep.

Meditation and yoga nidra scripts have been immensely

helpful for me in terms of accelerating the transition to

sleep.

So they involve taking a few minutes,

10 to 30 minutes or so,

just like you would for a nap and just listening to a script

almost passively.

And it has you do some particular patterns of breathing and

some other kind of body scan like things that can really

help people learn to relax, not just in that moment,

but get better at relaxing and turning off thinking in order

to fall asleep when they want to do that at night.

There’s another thing that’s similar to this,

which is certain forms of hypnosis for sleep for that.

I’ll just refer you to the website of a colleague and

collaborator of mine, David Spiegel,

who’s our associate chair of psychiatry and behavioral

sciences at Stanford.

He’s developed a website, which is reverie,

R E V E R I E health.com.

So reveriehealth.com that has a lot of science supported,

clinically supported hypnosis scripts that essentially take

the brain into states of deep relaxation for sake of

rewiring the brain and neuroplasticity.

But one of those scripts that’s there and is available free

is for sleep.

And we’ll talk more about hypnosis at a later time because

it has a ton of other effects that aren’t just limited to

sleep.

So a period of time each day that you devote to getting

better at falling and staying asleep is actually a really

good practice to adopt.

The other thing about these practices like meditation,

yoga, nidra, and hypnosis is people always say to me,

well, when should I do them?

And I always say, well,

the best time of day to do it is when you first wake up in

the morning, provided you’ve gotten your sunlight already,

anytime you wake up in the middle of the night or any time

of day. In other words,

they’re always good for you because it’s a training

mechanism by which you self-train your nervous system to go

from a state of heightened alertness that you don’t want to

heighten relaxation that you do want.

And so it’s really teaching you to hit the brake.

And that brings us to an even more important point perhaps,

which is we’ve all experienced that we can stay up if we

want to, right?

If we want to stay up late on new years,

or we want to push an all nighter,

some people can do that more easily than others,

but we’re all capable of doing that.

But it’s very hard to make ourselves fall asleep.

And so there’s a sort of asymmetry to the way our autonomic

nervous system, which governs this alertness,

calmness thing,

the sympathetic and parasympathetic nervous system.

There’s an asymmetry there where we are more easily able to

engage wakefulness and drive wakefulness.

We can force ourselves to stay awake.

Then we are able to force ourselves to fall asleep.

And one of the things that I say over and over again,

and I’m going to continue to say over and over again,

is it’s very hard to control the mind with the mind.

When you have trouble falling asleep,

you need to look to some mechanism that involves the body and

all the things I described, meditation, hypnosis,

yoga, Nidra, all involve exhale,

breathing certain ways of lying down and controlling the

body.

We’re going to get into breathing in real depth at another

time,

but all of those involve using the body to control the mind

rather than trying to, you know,

wrestle your mind into a certain pattern of relaxation.

So earlier in episode one,

I talked about the Mobius strip,

this continuous loop that is the brain body relationship or

the mind body relationship.

And when we’re having trouble controlling the mind,

I encourage people to look towards the body,

look toward sunlight, avoid sunlight, if in bright light,

if that happens to be late at night.

So there’s a theme that’s starting to emerge,

which is in order to control this thing that we call the

nervous system,

we have to look back to some of the things we discussed

earlier, like sensation, perception, et cetera.

But we have to ask, what can we control?

Well, I’m talking about controlling light exposure,

controlling your breathing and body.

I’m not going into details right now,

but you can see the yoga Nidra script or the reverie

health.com or headspace would be a great place to adopt the

meditation practice.

Any of those are really teaching you to use your body,

to control your mind and to allow you to explore the mind

body relationship in a way that gives you more control over

your mind and the mind body relationship.

Okay. So we talked about light.

We talked about activity and timing of light,

talked about the usefulness of naps and these things that

I’m calling non-sleep deep rest,

which include meditation, yoga, Nidra, and hypnosis,

non-sleep deep rest, or what I hereafter,

we will refer to as NSDR, not to be confused with EMDR.

I don’t think I’ve ever heard NSDR.

So I’m, I’m planting a flag for NSDR,

non-sleep deep rest as a way to reset one’s ability to be

awake after you emerge from NSDR.

So to get some more wakefulness and ability to attend some

emotional stability,

reset as well as make it better and easier to fall asleep

when you want to go to sleep at night.

Now non-sleep deep rest does have some research to support

it. There’s a beautiful study done out of a university in

Denmark. I will later provide a link to that study that

showed that this meditation and yoga,

Nidra type meditation allows dopamine and other

neuromodulators in an area of the brain called the striatum

that’s involved in motor planning and motor execution to

reset itself. In other words,

this NSDR can reset our ability to engage in the world in a

way that’s very deliberate in not to throw in another

acronym, but NSDR resets your ability to engage in DPOs,

duration, path, and outcome.

So now you’re probably rolling your eyes like, oh my

goodness, the number of acronyms, but just bear with me

because NSDR is so powerful because first of all,

it doesn’t require that you rig yourself to any device.

It doesn’t require that you take much time out of your day.

It doesn’t require that you ingest anything except air,

and it can have so many positive effects right down to the

neuromodulator level. So I think in years to come,

my lab’s exploring this in collaboration with David

Spiegel’s lab, but other labs are looking at this as well.

I think NSDR is going to start to play a more prominent role

in what we call wellness and health,

both mental health and physical health.

So I encourage you to explore those practices.

Okay, so what about things that we can and maybe should or

should not take in order to control and access better sleep

and better wakefulness?

We’ve talked about things you can do or not do.

We’ve talked about nutrition and the timing of nutrition.

Now let’s talk about compounds.

Those could be prescription drugs.

Those could be supplements.

There are a number of different things that will affect your

circadian timing and behavior.

In fact,

almost everything that you could take will affect your

circadian timing and behavior. That’s right.

So years ago, when I was in graduate school,

I had a professor, unfortunately he passed away now,

but his name was Ted Jones, the late Edward Jones,

who was a world-class neuroanatomist.

He wrote the book on the thalamus.

In fact, it’s called the thalamus and an expert on patterns

of activation in the brain during sleep.

And I’ll never forget that during one of these lectures,

someone asked Ted the question, you know,

what is the effect of some drug on these waves of activity

in the thalamus or something?

And his answer was incredible.

He was a pretty gruff guy.

And so his answer was delivered in the form of a kind of

aggressive direct statement.

He said a drug is a substance that when injected into a

person produces a scientific publication.

And what he was saying is actually quite true,

which is that most every compound will have some effect on

some aspect of biology.

This is why it’s hard to sort through everything

that’s on PubMed.

If you put any molecule or compound or drug into PubMed,

and then you put sleep next to it or alertness next to it,

you’re likely to find a paper where there’s an effect,

but that’s not necessarily telling you that that drug is

useful or helpful for that.

What it’s telling you is that anytime you change

what you take or you stop taking something,

say you’re taking sleeping pills,

Ambien or whatever it is, and you stop taking them,

your sleep behavior will change.

Let’s say you take an aspirin,

you don’t normally take aspirin.

You will shift your circadian rhythm.

Now you might not shift it perceptibly.

You might not create problems for yourself,

but anytime you ingest a compound at high potency,

you’re going to change,

provide some shift to your circadian rhythm.

Now that said,

there are a couple of things that are directly in line with

the biology related to falling and staying asleep and

directly in line with the biology of wakefulness.

There’s a whole category of things like stimulants,

cocaine, amphetamine, and prescription stimulants that are,

the prescription ones were designed for the treatment of

narcolepsy.

So things like modafinil or armadafinil that are designed to

create wakefulness.

They are all essentially chemical variants of things that

increase epinephrine and dopamine.

Now, of course,

I’m of the standpoint that things like cocaine,

amphetamine are just across the board bad.

They have so many addictive and terrible effects in the

proper setting prescribed by the proper professional things

like modafinil for narcolepsy might be appropriate.

I know that a lot of people out there take Adderall,

even though they haven’t been prescribed Adderall in order

to increase wakefulness.

That is essentially, you know, well, it’s illegal for one,

but it’s also it’s abusing the system in the sense that

you’re pushing back on the Adenosine system slightly

differently than you do caffeine.

It will make you feel more alert.

There tends to be a heavy rebound and they do have an

addictive potential.

There are also some other effects of those that can be quite

bad. So we’re going to explore a stimulants in a whole

month related to drugs,

but there are some supplements and some things that are

safer, certainly safer.

And that in cases where you’re doing all the right behaviors,

you’re exercising and eating correctly,

and you’re still having trouble with sleep that can be

beneficial for falling and staying asleep.

Now I want to be very clear. I am not pushing supplements.

I’m just pointing you towards some things that have been

shown in peer reviewed studies to have some benefit.

The first one is magnesium.

There are many forms of magnesium,

but certain forms of magnesium can have positive effects on

sleepiness and the ability to stay asleep mainly by way of

increasing neurotransmitters like GABA,

which help turn off the DPO,

the kind of thinking about the future duration,

path outcome analysis,

and make one sort of one’s mind kind of drift in space and

time and make it easier to fall asleep.

There are a lot of forms of magnesium out there,

but one in particular is magnesium threonate, T-H-R-E-O-N-A-T-E

which you have to check to see if this right is right for

you check with your doctor,

but magnesium threonate is associated with transporters in

the body that bring more of it into cells that allow people

to feel this kind of drowsiness and help them fall asleep.

So I personally,

I can only talk about what I personally do.

I personally take three or 400 milligrams of magnesium

threonate about 30 to 60 minutes before sleep.

And it helps me fall asleep.

The other thing is theanine, T-H-E-A-N-I-N-E,

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

a hundred to 200 milligrams of theanine for me also helps me

turn off my mind and fall asleep.

I take it 30 to 60 minutes throughout the day.

Interestingly,

theanine is now being introduced to a lot of energy drinks in

order to take away the jitters that are associated with

drinking too much caffeine or with some other things that

are in the energy drinks.

Energy drinks are, can be problematic.

They can contain a lot of L-taurine.

I’ll just tell you an anecdote.

When I was a postdoc,

I was drinking a lot of a particular energy drink,

has a lot of taurine in it.

And actually the whites of my eyes,

the sclera as it’s called in my eyes turned beet red.

And I went to a friend who’s an ophthalmologist.

I said, look, I’m not a marijuana smoker.

I haven’t been hit on the head.

I don’t know what’s going on.

And he looked and he said,

I think you’ve got some microvascular damage.

And we walked through what I was taking and doing.

And he said, oh, it’s probably the taurine,

excessive levels of taurine can create some

microvascular damage.

So if you’re having the microvascular damage in your eye,

you’re probably have microvascular damage deeper

in your skull.

So I stopped.

That’s the reason why I don’t take energy drinks.

So just a consideration.

Again, I’m not here to tell you what to do or not do,

but just want to arm you with information.

The thing about theanine and magnesium is taken together.

They do, for some people,

they can make them so sleepy and sleep so deeply

that they actually have trouble waking up in the morning.

So you have to play with these things and titrate them

if you decide to use them.

Again, if you decide to go this route,

I would not start by taking supplements.

I would start by getting your light viewing behavior

correct, and then think about your nutrition,

and then think about your activity,

and then think about whether or not you want a supplement.

We already talked about melatonin earlier.

There’s another supplement that could be quite useful,

which is apigenin, A-P-I-G-E-N-I-N,

which is a derivative of chamomile.

50 milligrams of apigenin also can augment

or support this kind of creation of a sleepiness

to help fall asleep and stay asleep.

A note about sleepwalkers and people with very vivid dreams.

Theanine can often make your dreams very vivid.

Sleepwalkers should be careful about taking theanine.

Everyone should be careful about taking anything,

and don’t take anything without consulting

your board certified MD or healthcare professional first.

Your health is your responsibility.

I am not going to take responsibility

for what you decide to do experimentally in any case,

but especially as it relates to supplementation and drugs.

As a important point,

apigenin is a fairly potent estrogen inhibitor.

So women who want to keep their estrogen levels high

or at whatever levels they happen to be at

should probably avoid apigenin altogether.

And men take that into consideration as well.

Men need estrogen also.

You don’t want to completely eliminate your estrogen.

That can create all sorts of bad effects

on libido and cognition, et cetera.

So apigenin in some people

is going to be a pretty strong estrogen inhibitor.

So keep that in mind.

There are other things you can take to help you sleep better.

Those are the legal ones that at least I’m aware of

have pretty broad safety margins.

But again, you need to explore your safety margins

with any compound.

I think a great website that I can refer you to

is examine.com.

Examine the word just as it sounds.

Dot com is a website.

I have no relation to them,

but there you can find links to peer-reviewed studies

for any compound or supplement,

as well as some important warnings

related to the things I discussed,

as well as any other thing

that you might decide to supplement with or ingest

to help improve your sleep.

Okay.

That was a lot of information

about how to get better at sleeping,

falling asleep, wakefulness, et cetera.

An important feature of this podcast, as you know,

is that we dive deep into topics

for several episodes at a time,

at least a month at a time.

So by stopping here,

I recognize that there are probably many more questions

that you still have.

And the great thing about that

is that we have another episode coming up soon.

I’m going to hold office hours

where I’m going to answer your specific questions

about episodes one and two.

So if you have questions about this episode,

you have questions about episode one,

write them down, put them in the comments.

I’ll also do a post on Instagram

where you can put them in the comments there,

but put them in the comments to this episode as well.

Please recommend the podcast if you like it.

Please subscribe to it here on YouTube.

Please subscribe to it on Apple.

We’re now on Spotify as well.

Recommend it to a friend.

The community that we’re creating here

around these topics of sleep and wakefulness

and other neuroscience and health-related themes

is best supported by your involvement and your questions.

Last but not least,

a number of you have very graciously asked

how you can support the podcast.

The best way to support the podcast

is to subscribe on YouTube or one of the other platforms.

We’re now on Spotify and Apple.

And the other way you can really support the podcast

is to check out our sponsors,

which were discussed at the beginning.

And as mentioned at the beginning of today’s episode,

we are now partnered with Momentous Supplements

because they make single ingredient formulations

that are of the absolute highest quality

and they ship international.

If you go to livemomentous.com slash Huberman,

you will find many of the supplements

that have been discussed on various episodes

of the Huberman Lab Podcast,

and you will find various protocols

related to those supplements.

Thank you so much for your time and attention.

And above all, thank you for your interest in science.

♪♪