Lex Fridman Podcast - #210 - Matt Walker: Sleep

The following is a conversation with Matt Walker,

sleep scientist, professor of neuroscience

and psychology at Berkeley, author of Why We Sleep,

and the host of a new podcast called The Matt Walker Podcast.

It’s 10 minute episodes a couple of times a month,

covering sleep and other health and science topics.

I love it and recommend it highly.

It’s up there with the greats,

like the Huberman Lab Podcast with Andrew Huberman,

and I think David Sinclair is putting out

an audio series soon too.

I can’t wait to listen to it.

I’m really excited by the future of science

in the podcasting world.

To support this podcast, please check out our sponsors,

Stamps.com, Squarespace, Athletic Greens,

BetterHelp, and Onnit.

Their links are in the description.

As a side note, let me say that to me,

a healthy life is one in which you fall in love

with the world around you, with ideas, with people,

with small goals and big goals, no matter how difficult,

with dreams you hold onto and chase for years.

Life should be lived fully.

That, to me, is the priority.

That, to me, is a healthy life.

Second to that is the understanding and the utilization

of the best available science on diet, exercise,

supplements, sleep, and other lifestyle choices.

To me, science in the realm of health is a guide

for what we should try, not the absolute truth

of how to live life.

The goal is to learn to listen to your body

and figure out what works best for you.

All that said, a good night’s sleep can be a great tool

in making life awesome and productive,

and Matt is a great advocate of the how and the why of sleep.

We agree on some things and disagree on others,

but he’s a great human being, a great scientist,

and, as of recently, a friend with whom I enjoy

having these wide ranging conversations.

This is the Lux Friedman podcast,

and here is my conversation with Matt Walker.

You should try these shades on.

Let’s see what you look like.

So they are now your shades, and that’s not the question.

It’s the same thing as Putin took the Super Bowl ring,

and it’s now his ring.

Yeah, one wonders if he was offered it,

but they are yours.

When did you first fall in love with the dream

of understanding sleep?

Like, where did the fascination with sleep begin?

So back in the United Kingdom,

you can sort of start doing medicine at age 18,

and it’s a five year program,

and I was at the Queen’s Medical Center in the UK,

and I remember just being fascinated

by states of consciousness, and particularly anesthesia.

I was thinking, isn’t that, within seconds,

I can take a perfectly conscious human being,

and I can remove all existence of the mentality

and their awareness within seconds,

and that stunned me.

So I started to get really interested in conscious states.

I even started to read a lot about hypnosis,

and all of these things, hypnosis,

even sleep and dreams at the time,

they were very esoteric.

It was sort of charlatan science at that stage,

and I think almost all of my colleagues and I

are accidental sleep researchers.

No one, as I recall, in the classroom

when you’re sort of five years old,

and the teacher says,

what would you like to be when you grow up?

No one’s putting their hand up and saying,

I would love to be a sleep researcher.

And so when I was doing my PhD,

I was trying to identify different forms of dementia

very early on in the course,

and I was using electrical brainwave recordings to do that,

and I was failing miserably.

It was a disaster, just no result after no result.

And I used to go home to the doctor’s residence

with this sort of little igloo of journals

that at the weekend I would sort of sit in and read,

and which I’m now thinking,

do I really want to admit this?

Because it sounds like I had no social life,

which I didn’t, I was a social leper.

But, and I started to realize that some parts of the brain

were sleep related areas,

and some dementias were eating away

those sleep related areas.

Other dementias would leave them untouched.

And I thought, well, I’m doing this all wrong.

I’m measuring my patients while they’re awake.

Instead, I should be measuring them while they’re asleep.

Started doing that, got some amazing results.

And then I wanted to ask the question,

is that sleep disruption that my patients are experiencing

as they go into dementia,

maybe it’s not a symptom of the dementia.

I wonder if it’s a cause of the dementia.

And at that point, which was, cough, cough, 20 years ago,

no one could answer a very simple fundamental question.

Why do we sleep?

And I at the time didn’t realize

that some of the most brilliant minds in scientific history

had tried to answer that question and failed.

And at that point, I just thought, well,

I’m going to go and do a couple of years of sleep research

and I’ll figure out why we sleep.

And then I’ll come back to my patients

in this question of dementia.

And as I said, that was 20 years ago.

And what I realized is that hard questions

care very little about who asks them.

They will meter out their lessons of difficulty

all the same.

And I was schooled in the difficulty of the question,

why do we sleep?

But in truth, 20 years later,

we’ve had to upend the question

rather than saying, why do we sleep?

And by the way, the answer then was

that we sleep to cure sleepiness,

which is like saying, we eat to cure hunger.

That tells you nothing about the physiological benefits

of food, same with sleep.

Now we’ve actually have to ask the question,

is there any physiological system in the body

or any major operation of the mind

that isn’t wonderfully enhanced when we get sleep

or demonstrably impaired when we don’t get enough?

And so far, for the most part, the answer seems to be no.

So far, the answer seems to be no.

So why does the body and the mind crave sleep?

Crave sleep then?

Why do we sleep?

How can we begin to answer that question then?

So I think one of the ways that I think about this

or one of the answers that came to me is the following.

The reason that we implode so quickly

and so thoroughly with insufficient sleep

is because human beings seem to be one of the few species

that will deliberately deprive themselves of sleep

for no apparent good reason, biological.

And what that led me then to was the following.

Mother nature as a consequence.

So no other species does what we do in that context.

There are a few species that do undergo sleep deprivation,

but for very obvious, clear biological reasons.

One is when they’re in a condition of severe starvation.

The second is when they’re caring for their newborn.

So for example, killer whales will often deprive themselves.

The female will go away from the pod, give birth,

and then bring the calf back.

And during that time,

the mother will undergo sleep deprivation.

And then the third one is during migration

when birds are flying trans oceanographic 2,000, 3,000 miles.

But for the most part,

it’s never seen in the animal kingdom,

which brings me back to the point,

therefore mother nature in the course of evolution

has never had to face the challenge of this thing

called sleep deprivation.

And therefore she has never created a safety net in place

to circumnavigate this common influence.

And there is a good example where we have,

which is called the adipose cell, the fat cell.

Because during our evolutionary past,

we had famine and we had feast.

And mother nature came up with a very clever recipe,

which is how can I store caloric credit

so that I can spend it when I go into debt?

And the fat cell was born, brilliant idea.

Where is the fat cell for sleep?

Where is that sort of banking chip for sleep?

And unfortunately we don’t seem to have one

because she’s never had to face that challenge.

So even if there’s not some kind of physics,

fundamental need for sleep

that physiologically or psychologically,

the fact is most organisms are built such that they need it.

And then mother nature never built an extra mechanism

for sleep deprivation.

So it’s interesting that why we sleep

might not have a good answer,

but we need to sleep to be healthy is nevertheless true.

Yeah, and we have many answers right now.

In some ways the question of why we sleep

was the wrong question too.

It’s what are the plory potent many reasons we sleep?

We don’t just sleep for one reason

because from an evolutionary perspective,

it is the most idiotic thing that you could imagine.

When you’re sleeping, you’re not finding a mate,

you’re not reproducing,

you’re not caring for your young,

you’re not foraging for food,

and worse still, you’re vulnerable to predation.

So on any one of those grounds,

especially as a collective,

sleep should have been strongly selected against

in the course of evolution.

But in every species that we’ve studied carefully to date,

sleep is present.

Yeah, so it is important.

So like you’re right.

I think I’ve heard arguments

from an evolutionary biology perspective

that sleep is actually advantageous,

maybe like some kind of predator prey relationships.

But you’re saying,

and it actually makes way more sense what you’re saying

is it should have been selected against.

Like why close your eyes?

Yeah, why?

Because there was an energy conservation hypothesis

for a while,

which is that we need to essentially go

into low battery mode, power down,

because it’s unsustainable.

But in fact, that actually has been blasted out the water

because sleep is an incredibly active process.

In fact, the difference between you just lying on the couch

but remaining conscious versus you lying on the couch

and falling asleep,

it’s only a savings of about 140, 150 calories.

In other words, you just go out

and club another baby seal or whatever it was,

and you wouldn’t worry.

So it has to be much more to it than energy conservation,

much more to it than sharing ecosystem space and time,

much more to it than simply predator prey relationships.

If sleep really did,

and looking back,

even very old evolutionary organisms like earthworms,

millions of years old,

they have periods where they’re active

and periods where they’re passively asleep.

It’s called lethargicus.

And so what that in some ways suggested to me

was sleep evolved with life itself on this planet,

and then it has fought its way through heroically

every step along the evolutionary pathway,

which then leads to the sort of famous sleep statement

from a researcher that if sleep doesn’t serve

an absolutely vital function or functions,

then it’s the biggest mistake

the evolutionary process has ever made.

And we’ve now realized Mother Nature

didn’t make a spectacular blender with sleep.

You’ve mentioned the idea of conscious states.

Do you think of sleep

as a fundamentally different conscious state than awakeness?

And how many conscious states are there

so when you’re into it,

you’re understanding of what the mind can do,

do you think awake state, sleep state,

or is there some kind of continuum?

There’s a complicated state transition diagram.

Like how do you think about this whole space?

I think about it as a state space diagram.

And I think it’s probably more of a continuum

than we have believed it to be or suggested it to be.

So we used to think absent of anesthesia

that there were already three main states of consciousness.

There was being awake, being in non rapid eye movement sleep

or non dream sleep,

and then being in rapid eye movement sleep or dream sleep.

And those were the three states

within which your brain could percolate and be conscious.

Conscious during non REM sleep is maybe a stretch to say,

but I still believe there is plenty of consciousness there.

I don’t believe that though anymore.

And the reason is because we can have daydreams

and we are in a very different wakeful state

in those daydreams than we are when we are as we are now

together present and extra septively focused

rather than intra septively focused.

And then we also know that as you are sort of progressing

into those different stages of sleep during non REM sleep,

you can also still dream,

depends on your definition of dreaming,

but we seem to have some degree of dreaming

in almost all stages of sleep.

We’ve also then found that when you are sleep deprived,

there are even individual brain cells will fall asleep.

Despite the animal being, you know,

behaviorally from best we can tell awake,

individual brain cells and clusters of brain cells

will go into a sleep like state.

And humans do this too.

When we are sleep deprived,

we have what are called microsleeps

where the eyelid will partially close

and the brain essentially falls lapses

into a state of sleep,

but behaviorally you seem to be awake.

And the danger here is road traffic accidents.

So these are the,

what we call these sort of microsleep events at the wheel.

Now, if you’re traveling at 65 miles an hour

in a two ton vehicle,

you know, it takes probably around one second

to drift from one lane to the next

and it takes two seconds to go completely off the road.

So if you have one of these microsleeps at the wheel,

you know, it could be the last microsleep

that you ever have.

But I don’t now see it as a set of,

you know, very binary distinct,

you know, step function state.

It’s not a one or a zero.

I see it more of a, as a continuum.

So I’ve for five, six years at MIT

really focused on this human side of driving question.

And one of the big concerns is the microsleeps,

drowsiness, these kinds of ideas.

And one of the open questions was,

is it possible through computer vision to detect

or any kind of sensors?

The nice thing about computer vision

is you don’t have to have direct contact to the person.

Is it possible to detect increases in drowsiness?

Is it possible to detect these kinds of microsleeps

or actually just sleep in general?

Among other things, like distraction,

these are all words that have so many meanings

and so many debates, like attention is a whole nother one.

Just because you’re looking at something

doesn’t mean you’re loading in the information.

Just because you’re looking away

doesn’t mean your peripheral vision

can’t pick up the important information.

There’s so many complicated vision science things there.

So I wonder if you could say something to,

they say the eyes are the windows to the soul.

Do you think the eyes can reveal

something about sleepiness through computer vision,

just looking at the video of the face?

And Andrew Huberman and I, your friend,

have talked about this.

I would love to work on this together.

It’s a fascinating problem.

But drowsiness is a tricky one.

So there’s, what kind of information?

There’s blinking and there’s eye movement.

And those are the ones that can be picked up

with computer vision.

Do you think those are signals that could be used

to say something about where we are in this continuum?

Yeah, I do.

And I think there are a number of other features too.

I think, you know, aperture of eye.

So in other words, partial closures, full closures,

duration of those closures, duration of those partial

closures of the eyelid.

I think there may be some information in the pupil as well,

because as we’re transitioning between those states,

there are changes in what’s called

the automatic nervous system,

or technically it’s called the autonomic nervous system,

part of which will control your pupillary size.

So I actually think that there is probably

a wealth of information.

When you combine that probably with aspects of steering,

angle steering maneuver.

And if you can sense the pressure on the pedals as well,

my guess is that there is some combinatorial feature

that creates a phenotype of,

you are starting to fall asleep.

And as the autonomous controls develop,

that it’s time for them to kick in.

Some manufacturers, auto manufacturers sort of have

something beta version, maybe an alpha version of this

already starting to come online,

where they have a little camera in the wheel

that I think tries to look at some features.

Almost everybody doing this and it’s very alpha.

So, you know, the thing that you currently have,

some people have that in their car,

there’s a coffee cup or something that comes up

that you might be sleepy.

The primary signal that they’re comfortable using

is the steering wheel reversals.

So basically using your interaction with the steering wheel

and how much you’re interacting with it

as a sign of sleepiness.

So if you have to constantly correct the car,

that’s a sign of like you starting to drift

into microsleep.

I think that’s a very, very crude signal.

It’s probably a powerful one.

There’s a whole nother component to this,

which is it seems like it’s so driver and subject dependent.

How our behavior changes as we get sleepy and drowsy

seems to be different in complicated, fascinating ways

where you can’t just use one signal.

It’s kind of like what you’re saying,

there has to be a lot of different signals

that you should then be able to combine.

The hope is there’s the searches for like universal signals

that are pretty damn good for like 90% of people.

But I don’t think we need

to take necessarily quite that approach.

I think what we could do in some clever fashion

is using the individual.

So what you and I are perhaps suggesting here

is that there is an array of features

that we know provide information

that is sensitive to whether or not

you’re falling asleep at the wheel.

Some of those, let’s say that there are 10 of them,

for me, seven of them are the cardinal features.

For you, however, you know, six of them

and they’re not all the same sort of overlapping

are those for you.

I think what we need is algorithms

that can firstly understand when you are well slept.

So let’s say that people have sleep trackers at night

and then your car integrates that information

and it understands when you are well slept.

And then you’ve got the data of the individual behavior

unique to that individual, snowflake like,

when they are well slept.

This is the signature of well rested driving.

Then you can look at deviations from that

and pattern match it with the sleep history

of that individual.

And then I don’t need to find the sort of, you know,

the one size fits all approach for 99% of the people.

I can create a very bespoke tailor like set of features,

a Savile Row suit of sleepiness features.

You know, that would be my,

if you want to ask me about moon shots and crazy ideas,

that’s where I go.

But to start with, I think your approach is a great one.

Let’s find something that covers 99% of the people

because the worrying thing about microsleeps of course,

unlike, you know, drugs or alcohol, which you know,

certainly is a terrible thing to be behind the wheel.

With those often you react too late.

And that’s the reason you get into an accident.

When you fall asleep behind the wheel,

you don’t react at all.

You know, at that point,

there is a two ton missile driving down the street

and no one’s in control.

That’s why those accidents can often be more dangerous.

Yeah, and the fascinating thing is,

in the case of semi autonomous vehicles,

like Tesla autopilot,

this is where I’ve had disagreements with Mr. Elon Musk,

and the human factors community,

which is this community that one of the big things they study

is human supervision over automation.

So you have like pilots, you know, supervising an airplane

that’s mostly flying autonomously.

The question is, when we’re actually doing the driving,

how do microsleeps or general,

how does drowsiness progress

and how does it affect our driving?

That question becomes more fascinating, more complicated

when your task is not driving,

but supervising the driving.

So your task is to take over when stuff goes wrong.

And that is complicated,

but the basic conclusions from many decades

is that humans are really crappy at supervising

because they get drowsy and lose vigilance much, much faster.

The really surprising thing with Tesla autopilot,

it was surprising to me,

surprising to the human factors community,

and in fact, they still argue with me about it,

is it seems that humans in Teslas with autopilot

and other similar systems are not becoming less vigilant,

at least with the studies we’ve done.

So there’s something about the urgency of driving.

I can’t, I’m not sure why,

but there’s something about the risk,

I think the fact that you might die

is still keeping people awake.

The question is, as Tesla autopilot

or similar systems get better and better and better,

how does that affect increasing drowsiness?

And that’s when you need to have,

that’s where the big disagreement was,

you need to have driver sensing,

meaning driver facing camera

that tracks some kind of information about the face

that can tell you drowsiness.

So you can tell the car if you’re drowsy

so that the car can be like,

you should be probably driving or pull to the side.

Right, or I need to do some of the heavy lifting here.

Yeah, so there needs to be that dance of interaction

of a human and machine,

but currently it’s mostly steering wheel based.

So this idea that your hands should be

on the steering wheel,

that’s a sign that you’re paying attention

is an outdated and a very crude metric.

I agree, yeah.

I think there are far more sophisticated ways

that we can solve that problem if we invest.

Can I ask you a big philosophical question

before we get into fun details?

On the topic of conscious states,

how fundamental do you think is consciousness

to the human mind?

I ask this from almost like a robotics perspective.

So in your study of sleep,

do you think the hard question of consciousness

that it feels like something to be us,

is that like a nice little feature,

like a quirk of our mind,

or is it somehow fundamental?

Because sleep feels like we take a step out

of that consciousness a little bit.

So from all your study of sleep,

do you think consciousness is like deeply part of who we are

or is it just a nice trick?

I think it’s a deeply embedded feature

that I can imagine has a whole panoply

of biological benefits.

But to your point about sleep,

what is interesting if you do a lot of dream research

and we’ve done some,

it’s very, very rare at all, in fact,

for you to end up becoming someone

other than who you are in your dreams.

Now you can have third person perspective dreams

where you can see yourself in the dream

as if you’re sort of,

you’ve risen above your physical being.

But for the most part,

it’s very rare that we lose our sense of conscious self.

And maybe I’m sort of doing a sleight of hand

because it’s really what I’m saying,

it’s very rare that we lose our sense

of who we are in dreams.

We never do.

Now that’s not to suggest that dreams aren’t utterly bizarre.

And I mean, when you slept last night,

which I know may have been perhaps a little less than me,

but when you went into dreaming,

you became flagrantly psychotic.

And there are five essentially good reasons.

Firstly, you started to see things which were not there,

so you were hallucinating.

Second, you believe things that couldn’t possibly be true,

so you were delusional.

Third, you became confused about time and place and person,

so you’re suffering from what we would call disorientation.

Fourth, you have wildly fluctuating emotions,

something that psychiatrists

will call being affectively labile.

And then how wonderful, you woke up this morning

and you forgot most if not all of that dream experience,

so you’re suffering from amnesia.

If you were to experience any one of those five things

while you’re awake,

you would probably be seeking psychological help.

But so I place that as a backdrop

against your astute question,

because despite all of that psychosis,

there is still a present self nested at the heart of it,

meaning that I think it’s very difficult for us

to abandon our conscious sense of self.

And if it’s that hard,

the old adage in some ways,

that you can’t outrun your shadow.

But here it’s more of a philosophical question,

which is about the conscious mind

and what the state of consciousness actually means

in a human being.

So I think that that to me,

you become so dislocated from so many other rational ways

of waking consciousness.

But one thing that won’t go away,

that won’t get perturbed or sort of, you know,

manacled, is this your sense of conscious self?

Yeah, that’s a strong sign that consciousness

is fundamental to the human mind.

Or we’re just creatures of habit

who gotten used to having consciousness.

Maybe it just takes a lot of either chemical substances

or a lot of like mental work to escape that.

I mean, it’s like trying to launch a rocket.

You know, the energy that has to be put in

to create escape velocity

from the gravitational pull of this thing

called planet earth is immense.

Well, the same thing is true

for us to abandon our sense of conscious self.

The amount of biological, the amount of substances,

the amount of wacky stuff that you have to do

to truly get escape velocity from your conscious self.

What does that tell us about then

the fundamental state of our conscious self?

Yeah, it also probably says that it’s quite useful

to have consciousness for survival

and for just operation in this world.

And perhaps for intelligence.

I’m one of the, on the AI side,

people that think that intelligence requires consciousness.

So like high levels of general intelligence

requires consciousness.

Most people in the AI field think like consciousness

and intelligence are fundamentally different.

You could build a computer that’s super intelligent.

It doesn’t have to be conscious.

I think that if you define super intelligence

by being good at chess, yes.

But if you define super intelligence

as being able to operate in this living world of humans

and be able to perform all kinds of different tasks,

consciousness, it seems to be somehow fundamental

to richly integrate yourself into the human experience,

into society.

It feels like you have to be a conscious being.

But then we don’t even know what consciousness is

and we certainly don’t know how to engineer it

in our machines.

I love the fact that there are still questions

that are so embryonic because, you know,

I suspect it’s the same with you.

Answers to me are simply ways to get to more questions.

You know, it’s questions where, you know,

questions turn me on, answers less so.

And I love the fact that we are still embryonic

in our sense of arguing about

even what the definition of consciousness is.

But I also find it fascinating.

I think it’s thoroughly delightful

to absorb yourself in the thought.

Think about the brain and we can move back

across the complexity of phylogeny

from, you know, humans to mammals

to sort of birds to reptiles, amphibians, fish.

You can, bacteria, whatever you want.

And you can go through this and say, okay,

where is the hard line of, you know,

what we would define as consciousness?

And I’m sure it’s got something to do

with the complexity of the neural system.

Of that, I’m fairly certain.

But to me, it’s always been fascinating.

So what is it then?

You know, is it that I just keep adding neurons

to a Petri dish and I just keep adding them

and adding them and adding them.

At some point when I hit a critical mass

of interconnected neurons, that is the mass of the,

you know, the interconnected human brain, then bingo.

All of a sudden it kicks into gear

and we have consciousness.

Like a phase shift, phase transition of some kind.

Correct, yeah.

But there is something about the complexity

of the nervous system that I think

is fundamental to consciousness.

And the reason I bring that up is because

when we’re trying to then think about creating it

in an artificial way, does that inform us

as to the complexity that we should be looking at

in terms of development?

I also think that it’s a missed opportunity

in the sort of digital space for us

to try to recreate human consciousness.

We’ve already got human consciousness.

What if we were to think about creating

some other form of, why do we have to think

that the ultimate in the creation of, you know,

an artificial intelligence is the replication,

you know, of a human state of consciousness?

Can we not think outside of our own consciousness

and believe that there is something even more incredible

or more complimentary, more orthogonal?

So I’m sometimes perplexed that people

are trying to mimic human consciousness

rather than think about creating

something that’s different.

I think of human consciousness or consciousness in general

as this magic superpower that allows us

to deeply experience the world.

And just as you’re saying, I don’t think that superpower

has to take the exact flavor as humans have.

That’s my love for robots.

I would love to add the ability to robots

that can experience the world and other humans deeply.

I’m humbled by the fact that that idea

does not necessarily need to look anything like

how humans experience the world.

But there’s a dance of human to robot connection

the same way human to dog or human to cat connection,

that there’s a magic there to that interaction.

And I’m not sure how to create that magic,

but it’s a worthy effort.

I also love, just exactly as you said,

on the question of consciousness

or engineering consciousness,

the fun thing about this problem

is it seems obvious to me that a hundred years from now,

no matter what we do today,

people, if we’re still here,

will laugh at how silly our notions were.

So like, it’s almost impossible for me to imagine

that we will truly solve this problem fully in my lifetime.

And more than that,

everything we’ll do will be silly a hundred years from now,

but it’s still, that makes it fun to me

because it’s like you have the full freedom

to not even be right, just to try.

Just to try is freedom.

And that’s how I see that.

Get me that T shirt, please.

I love that.

So, and human robot interaction is fascinating

because it’s like watching dancing.

I’ve been dancing tango recently

and just, it’s like, there is no goal.

The goal is to create something magical

and whether consciousness or emotion

or elegance of movement,

all of those things aid in the creation of the magic.

And it’s a free, it’s an art form to explore

how to make that, how to create that

in a way that’s compelling.

Yeah, I love the line in Sense of a Woman with Al Pacino

where he’s speaking about the tango

and he said, really, it’s just freedom

that if you get tangled up, you just keep tangoing on.

I still, to this day, I think first or second time

I talked to Joe Rogan on his podcast,

I said, we got into this heated argument

about whether Sense of a Woman

is a better movie than John Wick.

Because it’s one of my favorite movies for many reasons.

One is Sense of a Woman.


I didn’t know that, by the way.

I was just gonna.

You just.

Yeah, I didn’t know if you would actually know

of the movie.

Awesome, awesome.

No, yeah, I said, I love the tango scene.

I love Al Pacino’s performance.

It’s a wonderful movie.

Then Joe was saying, John Wick is better.

So we, to this day, argue about this.

I think it depends on what conscious state you’re in

that you would be ready and receptive to.

But Sense of a Woman, I think it has one of the best

monologues at the end of the movie

that has ever been written or at least performed.

When Al Pacino defends the younger.

Yeah, I often think about that.

There’s been times in my life, I don’t know about you,

where I wish I had an Al Pacino in my life,

where integrity is really important in this life.

It is.

And sometimes you find yourself in places

where there’s pressure to sacrifice that integrity.

And you want, what is it, Lieutenant Colonel

or whatever he was.

To come in.


To come in on your side and scream at everyone

and say, what the hell are we doing here?

Being, you know, unfortunately British

and sort of having that slightly awkward

sort of Hugh Grant gene.

It’s very, very, very at the opposite end of the spectrum

of the remarkable feat of Al Pacino

at the end of that scene.

But, and yeah, integrity is, it’s a challenging thing

and I value it much.

And I think it can take 20 years to build a reputation

and two minutes to lose it.

And there is nothing more that I value than that integrity

and, you know, if I’m ever wrong about anything,

I truly don’t want to be wrong for any longer

than I have to be.

You know, that’s what being in some ways a scientist is.

You’re just driven by truth.

And the irony relative to something like mathematics

is that in science, you never find truth.

What you do in science is you discount the things

that are likely to be untrue,

leaving only the possibility of what could be true.

But in math, you know, when you create, you know, a proof,

it’s a proof for, you know, from that point forward,

there is truth in mathematics.

And there’s, I think there’s a beauty in that,

but I kind of like the messiness of science

because again, to me, it’s less about the truth

of the answer and it is more about the pursuit of questions.

But their integrity becomes more and more important

and it becomes more difficult.

There’s a lot of pressures,

just like in the rest of the world,

but there’s a lot of pressures than a scientist.

One is like funding sources.

I’ve noticed this, that, you know,

money affects everyone’s mind, I think.

I’ve been always somebody that I believe money can’t,

you can’t buy my opinion.

I don’t care how much money, billions or trillions.

But that pressure is there and you have to be

very cognizant of it and make sure that your opinion

is not defined by the funding sources.

And then the other is just your own success of, you know,

for a couple of decades, publishing an idea

and then realizing at some point

that that idea was wrong all along.

And that’s a tough thing for people to do,

but that’s also integrity is to walk away,

is to say that you were wrong.

That doesn’t have to be in some big dramatic way.

It could be in a bunch of tiny ways along the way.


Like reconfigure your intuition about a particular problem.

That’s, and all of that is integrity.

When everybody in the room, you know,

believes a certain thing,

everybody in the community believes a certain thing,

to be able to still be open minded in the face of that.

Yeah, and I think it comes down in some ways

to the issue of ego that you bond your correctness

or your rightness, your scientific theory

with your sense of ego.

You know, I’ve never found it that difficult to let go

of theories in the face of counter evidence

in part because I have such low self esteem.

Well, I kind of liked that.

I always liked that combination.

I have the same, I’m like very self critical,

imposter syndrome, all those things,

putting yourself below the podium,

but at the same time having the ego

that drives the ambition to work your ass off.

Like some kind of weird drive,

maybe like drive to be better.

Like thinking of yourself as not that great

and always driving to be better.

And then at the same time,

because that can be paralyzing and exhausting and so on,

at the same time, just being grateful to be alive.

But in the sciences, in the actual effort,

never be satisfied, never think of yourself highly.

It seems to be a nice combination.

I very much hope that that is part of who I am

and I remain very quietly motivated and driven.

And I, like you, love the idea of perfection

and I know I will never achieve it,

but I will never stop trying to.

So similar to you, which sounds weird

because there’s all these videos of me on the internet.

So I think I just naturally lean into the things

I’m afraid of and I’m uncomfortable doing.

Like I’m very afraid of talking to people

and just even before talking to you today,

just a lot of anxiety and all those kinds of things.

About talking to me?

Yeah, yeah.

Oh, I like.


Fear in some cases, self doubt and all those kinds of things.

But I do it anyway.

So the reason I bring that up

is you’ve launched a podcast.

I have.

Allow me to say, I think you’re a great science communicator.

So this challenge of being afraid

or cautious of being in the public eye

and yet having a longing to communicate

some of the things you’re excited about

in the space of sleep and beyond.

What’s your vision with this project?

I think firstly to that question, like you,

I am always more afraid of not trying than trying.


That to me frightens me more.

But with the podcast,

I think really I have two very simple goals.

I want to try and democratize the science of sleep

and in doing so,

my goal would be to try and reunite humanity

with the sleep that it is so desperately bereft of.

And if I can do that through a number of different means,

the podcast is a little bit different than this format.

It’s going to be short form monologues from yours truly

that will last usually less than just 10 minutes.

And I see it as simply a little slice of sleep goodness

that can accompany your waking day.

It’s hard to know what is the right way

to do science communication.

Like your friend, mine, Andrew Huberman,

he’s an incredible human being.

Oh gosh.

So he does like two hours of,

I wonder how many takes he does.

I don’t know, but it looks like he doesn’t do any.

Yeah, I suspect he’s that magnificent of a human being.

When I talk to him in like in person,

he always generates intelligent words,

well cited, nonstop for hours.

So I don’t.

He’s a Gatling gun of information and it’s pristine.

And passion and all those kinds of things.

So that’s an interesting medium.

I wouldn’t have,

it’s funny because I wouldn’t have done it

the way he’s doing it.

I wouldn’t advise him to do it the way he’s doing it.

Cause I thought there’s no way you could do

what you’re doing.

Cause it’s a lot of work,

but he is like doing an incredible job of it.

I just think it’s the same with like Dan Carlin

and hardcore history.

I thought that the way Andrew’s doing it

would crush him the way it crushes Dan Carlin.

So Dan has so much pressure on him to do a good job

that he ends up publishing like two episodes a year.

So that pressure can be paralyzing.

The pressure of like putting out like

strong scientific statements

that can be overwhelming.

Now, Andrew seems to be just plowing through anyway.

If there’s mistakes, he’ll say there’s corrections and so on.

I just, I wonder,

I actually haven’t talked to him too much about it.

Like psychologically, how difficult is it

to put yourself out there for an hour to a week

of just nonstop dropping knowledge.

Any one sentence of which could be totally wrong.

It could be a mistake.

And there will be mistakes.

And I, in the first edition of my book,

there were errors that we corrected

in the second edition too.

But there will be probabilistically,

if you’ve got 10 facts per page of a book

and you’ve got 350 pages,

odds are it’s probably not going to be

utter perfection out the gate.

And it will be the same way for Andrew too.

But having the reverence of

a humble mind

and simply accepting the things that are wrong

and correcting them and doing the right thing.

I know that that’s his mentality.

I do want to say that I’m just kind of honored to be,

it’s a cool group of like scientific people

that I’m fortunate enough to now be interacting with.

It’s you and Andrew and David Sinclair

has been thinking about throwing his hat in the ring.

Oh, I hope so.

David is another one of those very special people

in the world.

So it’s cool because podcasts are, it’s cool.

It’s such a powerful medium of communication.

It’s much freer than more constrained

like publications and so on.

Or it’s much more accessible and inspiring than like,

I don’t know, conference presentations or lectures.

And so it’s a really exciting medium to me.

And it’s cool that there’s this like group of people

that are becoming friends and putting stuff out there

and supporting each other.

So it’s fun to also watch how that’s going to evolve

in your case, because I wonder it’ll be two a month.

Or devolve is the answer to that.

Well, I mean, some of it is persistence

through the challenges that we’ve been talking about,

which is like.

I think I’ve got a lot to learn.


But I will persist.

Can I ask you some detailed stuff?

You mentioned that.

Oh my goodness, go anywhere you wish with sleep.

So I’m a big fan of coffee and caffeine.

And I’ve been, especially in the last few days,

consuming a very large amount.

And I’m cognizant of the fact that my body is affected

by caffeine different than the anecdotal information

that other people tell me.

I seem to be not at all affected by it.

It’s almost, it feels like more like a ritual

than it is a chemical boost to my performance.

Like I can drink several cups of coffee right before bed

and just knock out anyway.

I’m not sure if it’s a biological chemical

or it has to do with just the fact

that I’m consuming huge amounts of caffeine.

All that to say, what do you think is the relationship

between coffee and sleep, caffeine and sleep?

If there’s an interesting distinction there.

There is a distinction.

So I think the first thing to say,

which is going to sound strange coming from me

is drink coffee.

The health benefits associated with drinking coffee

are really quite well established now.

But I think that the counterpoint to that,

well, firstly, the dose and the timing make the poison.

And I’ll perhaps come back to that in just a second.

But for coffee, it’s actually not the caffeine.

So, a lot of people have asked me

about this rightful paradox between the fact

that sleep provides all of these incredible health benefits

and then coffee, which can have a deleterious impact

on your sleep has a whole collection of health benefits.

Many of them Venn diagram overlapping

with those that sleep provides.

How on earth can you reconcile those two?

And the answer is that, well, the answer is very simple.

It’s called antioxidants, that it turns out

that for most people in Western civilization

because of diet, not being quite what it should be,

the major source through which they obtain antioxidants

is the coffee bean.

So the humble coffee bean has now been asked

to carry the astronomical weight of serving up

the large majority of people’s antioxidant needs.

And you can see this if, for example,

you look at the health benefits of decaffeinated coffee,

it has a whole constellation

of really great health benefits too.

So it’s not the caffeine.

And that’s why I liked what you said,

this sort of separation of church and state

between coffee and caffeine.

It’s not the caffeine, it’s the coffee bean itself

that provides those health benefits.

But coming back to how it impacts sleep,

it impacts sleep in probably at least three different ways.

The first is that for most people,

caffeine can make it obviously a little harder

to fall asleep.

Caffeine can make it harder to stay asleep.

But let’s say that you are one of those individuals

and I think you are, and you can say,

look, I can have three or four espressos with dinner

and I fall asleep just fine

and I stay asleep soundly across the night.

So there’s no problem.

The downside there is that even if that is true,

the amount of deep sleep that you get will not be as deep.

And so you will actually lose somewhere

between 10 to 30% of your deep sleep

if you drink caffeine in the evening.

So to give you some context,

to drop your deep sleep by let’s say 20%,

I’d probably have to age you by 15 years,

or you could do it every night with a cup of coffee.

I think the fourth component

that is perhaps less well understood about coffee

is its timing, and that’s why I was saying

the timing and the dose make the poison.

The dose, by the way,

once you get past about three cups of coffee a day,

the health benefits actually start to turn down

in the opposite direction.

So there is a U shape function.

It’s sort of the Goldilocks syndrome,

not too little, not too much, just the right amount.

The second component is the timing though.

Caffeine has half life of about five to six hours,

meaning that after five to six hours,

50% of that on average for the average adult

is still in the system,

which means that it has a quarter life of 10 to 12 hours.

So in other words, if you have a coffee at noon,

a quarter of that caffeine is still circulating

in your brain at midnight.

So having a cup of coffee at noon,

one could argue is the equivalent

of tucking yourself into bed at midnight,

and before you turn the light out,

you swig a quarter of a cup of coffee.

But that doesn’t still answer your question

as to why are you so immune?

So I’m someone who is actually unfortunately

very sensitive to caffeine.

And if I have even two cups of coffee in the morning,

I don’t sleep as well that night.

And I find it miserable because I love the smell of coffee.

I love the routine.

I love the ritual.

I think I would love to be invested in it.

It’s just terrible for my sleep.

So I switched to decaf.

There is a difference from one individual to the next,

and it’s controlled by a set of liver enzymes

called cytochrome P450 enzymes.

And there is a particular gene

that if you have a different sort of version of this gene,

it’s called CYP1A2.

That gene will determine the speed

of the clearance of caffeine from your system.

Some people will have a version of that gene

that is very effective and efficient

at clearing that caffeine.

And so their half life could be as short as two hours

rather than five to six hours.

Other people, hands up Matt Walker,

have a version of that gene

that is not very effective at clearing out the caffeine.

And therefore their half life sort of sensitivity

could be somewhere between eight to nine hours.

So we understand that there are individual differences,

but overall, I guess the top line here is drink coffee

and understand that it’s not the caffeine,

it’s the coffee that’s the benefit

and the dose makes the poison.

Is there some aspect to it that it’s like a muscle

in terms of all the combination of letters and numbers

that you just said?

Is there some aspect that if I can improve

the quarter life, the half life,

could decrease that number if I just practice?

Like I drink a lot of coffee,

so like habit alters how your body’s able

to get rid of the caffeine.

Not how the body is able to get rid of the caffeine,

but it does alter how sensitive the body is to the caffeine.

And it’s not at the level of the enzyme

degrading the caffeine.

It’s at the level of the receptors

that caffeine will act upon.

Now it turns out that those are called adenosine receptors

and maybe we can speak about what adenosine is

and sleep pressure and all of that good stuff.

But as you start to drink more and more coffee,

the body tries to fight back

and it happens with many different drugs by the way,

and it’s called tolerance.

And so one of the ways that your body becomes tolerant

to a drug is that the receptors that the drug is binding to,

these sort of welcome sites, these sort of picture myths,

as it were, that receive the drug,

those start to get taken away from the surface of the cell

and it’s what we call receptor internalization.

So the cell starts to think, gee whiz,

there’s a lot of stimulation going on, this is too much.

So I’m just going to, when normally I would coat my cell

with let’s just say five of these receptors

for argument’s sake,

things are going a little bit too ballistic right now.

I’m going to take away at least two of those receptors

and downscale it to just having three of those.

And now you need two cups of coffee to get the same effect

that one cup of coffee got you before.

And that’s why then when you go cold turkey on coffee,

all of a sudden the system has equilibrated itself

to expecting X amount of stimulation

and now all of that stimulation is gone.

So it’s now got too few receptors

and you have a caffeine withdrawal syndrome.

And that’s why, for example, with drugs of abuse,

things like heroin, when people go into abstinence,

as they’re sort of moving into their addiction,

they will build up a progressive tolerance to that drug.

So they need to take more of it to get the same high.

But then if they go cold turkey for some period of time,

the system goes back to being more sensitive again.

It starts to repopulate the surface of the cell

with these receptors.

But now when they reuse and they fall off the wagon,

if they go back to the same dose

that they were using before 10 weeks ago

or three months ago, that dose can kill them.

They can have an overdose.

Even though they were using the same amount

at those two different times,

the difference is that it’s not the dose of the drug,

it’s the sensitivity of the system.

And that’s the same thing that we see with caffeine.

In terms of training the muscle, as it were,

the system becomes less sensitive, can calibrate.

Is there a time, the number of hours before bed,

that’s a safe bet to most people to recommend

you shouldn’t drink caffeine this many hours?

Like, is there an average half life

that you should be aiming at?

Or is this advice kind of impossible

because there’s so much variability?

There is huge variability.

And I think everyone themselves to a degree knows it,

although I’ll put a caveat on that too

because it’s a slightly dangerous point.

So the recommendation for the average adult

and who, where is the average adult in society?

There is no such thing.

But for the average adult,

it would be probably cutting yourself off maybe 10 hours


So assuming a normative bedtime in society,

I would say try to stop drinking caffeine before 2 p.m.

and just keep an eye out.

And if you’re struggling with sleep,

dial down the caffeine and see if it makes a difference.

Can I ask you about sleep and learning?

So how does sleep affect learning?

Sleep before learning, sleep after learning,

which are both fascinating kind of dynamics

of the mind’s interaction with this extra conscious state.

Yeah, sleep is profoundly and very intimately related

to your memory systems and your informational systems.

The first is you just mentioned is that

sleep before learning will essentially prepare your brain

almost like a dry sponge ready to sort of,

you know, initially soak up new information.

In other words, you need sleep before learning

to effectively imprint information into the brain

to lay down fresh memory traces.

And without sleep, the memory circuits of the brain,

and we know we’ve studied these memory circuits,

will, you know, they essentially become waterlogged

as it were for the sponge analogy,

and you can’t absorb the information as effectively.

So you need sleep before learning,

but you also need sleep unfortunately after learning too,

to then take those freshly minted memories

and effectively hit the save button on them,

but it’s nowhere near as quick as a digital system.

It takes hours because it’s a physical biological change

that happens at the level of brain cells.

But sleep after learning will cement and solidify

that new memory into the neural architecture of the brain,

therefore making it less likely to be forgotten.

So, you know, I often think of sleep in that way as,

it’s almost sort of future proofing information.

In what way?

Well, it means that it gives it a higher degree of assurance

to be remembered in the future

rather than go through the sort of degradation

that we think of as forgetting.

So the brain has in some ways by default,

you know, there is forget,

and actually I would love to,

I was going to say sleep is relevant for memory

in three different ways,

but I’m going to amend that

and say there’s four different ways,

which is learning, maintaining, memorizing,

abstraction, assimilation, association, then forgetting,

which the last one sounds oxymoronic

based on the former three, but I’ll see if I can explain.

So sleep after learning then sort of, you know,

sets that information like amber in solidification.

The third benefit, however, is that sleep,

we’ve learned more recently is much more intelligent

than we ever gave it credit for.

Sleep doesn’t simply just take individual memories

and strengthen them.

Sleep will then intelligently integrate and cross link

and associate that information together.

And it’s almost like informational alchemy.

So that you wake up the next morning

with a revised mind wide web of associations.

And that’s probably the reason that, you know,

you’ve never been told to stay awake on a problem.

And in every language that I’ve inquired about that phrase

or something very similar seems to exist,

which means to me that this creative associative benefit

of sleep transcends cultural boundaries.

It is a common experience across humanity.

Now I should note that I think the French translation

of that is much closer to you.

I think you sleep with a problem.

Whereas the British, you sleep on a problem.

The French, you sleep with a problem.

I think it says so much about the romantic difference

between the British and the French, but let’s not go there.

That’s brilliant.

So such a subtle, but such a fundamental difference.


Oh, goodness me.

Sleep with the problem.

Yes, exactly.

That’s why I love the French.

So, and we can sort of double click on any one of these

and go into detail, but the fourth,

I became really enchanted by about eight years ago

in our research, which was this idea of forgetting.

And I started to think that forgetting may be the price

that we pay for remembering.

And in that sense, there is an enormous benefit

to letting go.

And you may be thinking, that sounds ridiculous.

I don’t want to forget.

In fact, my biggest problem is I keep forgetting things,

but the brain has a, well, we believe,

has a finite storage capacity.

We can’t prove it yet, but my suspicion is

that that’s probably true.

It doesn’t have an infinite storage capacity.

It has constraints.

If that’s the case, we can’t simply go through life

being constantly informational aggregators

unless we are programmed to say,

we’ve got a hard drive space of about 85 to 90 years

and we’re good and we can do that.

Maybe that’s true.

I don’t think that’s true.

I think forgetting is an incredibly good and useful thing.

So for example, it’s not beneficial

from an evolutionary perspective for me to remember

where I parked my car three years ago.

So it’s important that I can remember today’s parking spot,

but I don’t want to have the junk kind of DNA

from a memory perspective of where I parked my car

two years ago.

Now, I actually have in some ways a problem

with forgetting, and again, I’m not trying

to sort of be laudatory, but you know,

I tend not to forget too many things.

And I don’t think that that’s a good thing.

And there’s a wonderful neurologist, Luria,

who wrote a book called The Mind of the Mnemonicist.

And it was a brilliant book,

both because it was written exquisitely,

but he was studying these sort of memory savants

who basically could remember everything that he gave them.

And he tried to find a chink in their armor.

And the first half of the book is essentially about him

seeing how far he can push them before they fail.

And he never found that place.

He could never find a place where they stopped remembering.

And then in his brilliance,

he turned the question on its head.

He said, not what is the benefit of constantly remembering,

but instead, what is the detriment to never forgetting?

And when you start to realize his descriptions

of those individuals, it’s probably a life

that you would not want.

But it’s fascinating both from a human perspective,

but also AI perspective.

There’s a big challenge in the machine learning community

of how to build systems that are able to remember

for prolonged periods of time, lifelong continuous learning.

So where you build up information over time.

So memory is one of the biggest open problems

in AI and machine learning.

But at the same time,

the right way to formulate memory is actually forgetting

because you have to be exceptionally selective

at which kind of stuff you remember.

And that’s where the step of assimilation,

integration that you’re referring to is really important.

I mean, we forget most of the things.

And the question is exactly the cost of forgetting

at the very edge of stuff that could be important

or could not be, how do we remember or not those things?

Like for example, doing a podcast,

I’ve become cognizant of one feature of my forgetting

that’s been problematic, which is I forget names

and titles of books and so on.

So when I read, I remember ideas.

I remember quotes, I remember statements

and like that’s the space in which I’m thinking.

But when you communicate to others,

you have to say this person in this book said that.

So it’s the same thing with like Andrew Huberman

is masterful at this.

This is important academia,

remembering the authors of a paper

and the title of the paper as part of remembering the idea.

And I’ve been feeling the cost of not being able

to naturally remember those things.

And so that’s something I need to sort of work on,

but that’s an example.

Are you good with faces?

Yes, very good at faces.

But not good with names.

So I am exactly like you.

And there is an understanding of that in the brain too.

We understand that there is partitioning of those

in terms of the territory of the brain

that takes care of faces and facts and places

and that they can be separate.

So I will never forget a face,

but as I said, I usually forget very little,

but for some reason, names are a struggle.

I think in some ways,

because I’m probably just a slightly anxious person.

So when you first meet someone,

which is usually the time when a name is introduced,

you were saying you were sort of anxious maybe

about sort of sitting down with me,

but I find that a little bit activating.

And so it’s not as though there’s anything wrong

with my memory.

It’s just the emotional state I’m in

when I’m first meeting someone.

It’s a little bit perturbing,

but I will never forget the face.

I completely relate to that

because I almost don’t hear people’s names

when they tell me because I’m so anxious.


But I think there’s certain quirks of social interaction

that show that you care about the person,

that you remember that person,

that they matter to you,

that they had an impact on you.

And one of the ways to show that

is you remember their name.

But that’s a quirk to me

because a lot of people I meet have a deep impact on me,

but I can’t communicate that unless I know their name,

unless I know some of the details

that we humans seem to use to communicate

that we remember each other.

What I remember well is the feeling we shared,

is the experience we shared.

What I don’t remember well is the detailed labels

of those experiences.

And I need to certainly work on that.

I don’t know.

I think it’s just allowing yourself to be innate

and who you are is also a beautiful thing too.

I’m not suggesting it’s not important

to try and better oneself.

But I also sometimes worry about the misery

that that puts us in.

But like you, I do struggle with name,

but I know the first time when we met in the lobby,

I know exactly what you look like.

I know that you were wearing headphones.

I know the shape and the size of those headphones.

You didn’t have your black jacket on.

I know exactly what the weave of your shirt looked like

and what your shoes look like.

And I knew exactly the height of your,

the end of your pants from the top of your shoes.

And so those things I don’t forget.

And I can remember when people,

I met people two years ago and I’ll say,

oh yes, we met there.

And I remember you had those fantastic boots on.

I thought they were pretty great pair of boots.

And they’re like, how do you,

I didn’t even remember what I was wearing that day.

It’s fascinating.

Yeah, I’m the exact same way,

but you can’t, until we have Neuralink

or something like that,

we can’t communicate that you remember all those things.

I know, that’s what I wanted.

So you have to be able to use tricks

of human communication for that.

But so that, I mean, that’s the,

it’s ultimately is a trick of like,

which to remember, which to forget.

And the forgetting is so, it’s so fascinating to say this.

I mean, it seems to be deeply connected

to that assimilation process.

So forgetting, you try to fit all the new stuff

into this big web of the old stuff

and the things that don’t fit, you throw out.

I think the assimilation,

the way I’ve been thinking about it with sleep

and it’s particularly sort of dream sleep

that we think can help with this assimilation

is that during wake,

we have one version of associative processing.

And what I mean by that

is we see the most obvious connections.

So I think of wakefulness as a Google search gone right.

Whereas I see dream sleep as doing something very different.

I think dream sleep is a little bit

like group therapy for memories

that everyone gets a name badge

and sleep gathers in all of the individual pieces

of the day and it sort of starts to get you

to forces you, in fact, to speak to the people,

not at the front of the room

that you think you’ve got the most obvious connection with,

but to speak with the people all the way

at the back of the room that at first you think,

I’ve got no idea what’s going on in the room.

You think I’ve got no obvious connection with them at all.

But once you get chatting with them,

you learn that you do have a very distant,

non obvious connection,

but it’s still a connection on the same.

And it’s almost as though you’re doing a Google search

where I input Lex Friedman

and it doesn’t take me to the first page of your home site.

It takes me to page 20,

which is about some like field hockey game in Utah.

It turns out that there actually is a link.

If I look at it, it’s a distant, non obvious one.

And to me, I find that exciting

because when you fuse things together

that shouldn’t normally go together,

but when they do, they cause marked advances

in evolutionary fitness.

It sounds like the biological basis of creativity.

And that’s exactly what I think dream sleep

and the algorithm of dream sleep is designed to do.

It’s not a Boolean like system where you have

the sort of assumptions of true and false.

Maybe it’s more fuzzy logic system.

And I think REM sleep is a perfect environment

within which we do, it’s almost like memory pinball.

You get the information that you’ve learned during the day

and then you pull the lever back

and you shoot it up into the attic of your brain,

this cortex filled with all

of your past historical knowledge.

And you start to bounce it around

and see where one of those things lights up

and you build a new connection there

and you build another one there too.

You’re developing schemas.

And so in that way, I think you could argue,

we dream, therefore we are.

Yeah, so in terms of this line between learning

and thinking through a new thing

that seems to be deeply connected,

there’s this legendary engineer named Jim Keller

who keeps yelling at me about this.

He says it’s very effective.

He likes to, for difficult problems before bed,

think about that difficult problem.

We’re not talking about like drama at work

or all that kind of stuff.

No, like a scientific for him engineering problem.

He likes to like intensely think about it

to prime his mind before sleep and then go to sleep.

And then he finds that the next day,

he’s able to think much clearer

and there’s new ideas that come,

but also just, I guess it’s more well integrated.

And sometimes during the process of like,

he’s able to like wake up and like see new insights.

That’s right.

If he’s deeply sort of aggressively thinking through a problem.

And there’s many scientific demonstrations of this.

The Mendeleev with the periodic table of elements,

he was trying for months to understand.

I mean, talk about an ecumenical problem

of epic proportions.

Here’s your question today.

You have to understand how all of the known elements

in the universe fit together in a logical way.

Good luck, take care.

It was non trivial at the time.

And he would try and try, he was so obsessed with it.

He created playing cards

with all of the different elements on.

And then he would go on these long train journeys

around Europe and he would just sort of deal these cards

in front of them and he would shuffle them,

shuffling and shuffling.

And he would just try to see

if he could find what the answer was.

And then, so the story goes,

he fell asleep and he had a dream.

And in that dream,

all of these elements started to dance and play around

and they snapped into a logical grid,

atomic weights, et cetera, et cetera.

And it wasn’t his waking brain

that solved the problem.

It was his sleeping brain

that solved the impenetrable problem

that his waking brain could not.

And there’s been count,

even in the arts and in music,

some wonderful dreams,

Frankenstein, Mary Shelley’s epic Gothic novel

came to her in a dream at Lord Byron’s home.

And then we’ve got,

Paul McCartney.

Yesterday, the song came to him in a dream.

He was filming, gosh, what was the movie?

I don’t recall it.

I should be shocked because I’m from Liverpool myself.

And, but he was on Wimpole Street in London and filming.

And he came up with that song,

the melody in his sleep,

not to be outdone by the Beatles.

And by the way, Let It Be

also came from a dream that McCartney had.

People usually give it religious overtones.

Mother Mary comes to me speaking words of wisdom,

let it be.

If you’ve ever asked who Mother Mary is,

it’s not the biblical content.

It’s his mother.

It’s Mary McCartney.

And she came to him in a dream and gifted him the song.

But the best story I’ve heard

is not to be outdone by the Beatles.

The Stones, Keith Richards,

who I think once was suggested it.

Who was it?

It was a comedian who was saying that

in an interview with Rolling Stone,

Keith Richards suggested or inferred

that young kids should not do drugs.

And they said, well, look,

young kids can’t do drugs

because you’ve done all of the drugs.

And I always thought that,

but Keith Richards described he would always go to bed

with his guitar and a tape recorder.

And then probably who would have a whole set

of other things in the bed with him.

And who knows how many other people, but anyway.

And then he said in his autobiography,

and I’m paraphrasing here,

but one morning I woke up and I realized

that the tape had recorded all the way to the end.

So I rewound the tape and I hit play.

And there in some kind of ghostly form

were the opening chords to Satisfaction,

the most famous successful Rolling Stone song

of all time.

Followed by then 43 minutes of snoring.

That’s awesome.

That riff came to him.

One of the most famous riffs in all of rock and roll

came to him by way of a dream inspired insight.

So I think there is too many of those anecdotes.

And we’ve now got the side,

I don’t rely on anecdotes as science.

We’ve now done the studies in the laboratory

and we can reliably demonstrate

that sleep inspires creativity,

inspires problem solving capacity.

Well, the interesting thing is,

is it possible to some of the ideas that you talk about

to turn them into a protocol

that could be practiced rigorously?

So what Jim Keller espouses is saying,

not just the fact that sleep helps you

increase the creativity,

but turn it into a process.

Like literally, like don’t do it accidentally.

Like an athlete does certain things

to optimize their performance.

They have a training routine.

They have a regimen of like cycling and sprints

and long distance stuff.

In the same way, thinking about your job

as an idea generator in the engineering space

is like, this is good for my performance.

So like for an hour before bed,

think through a problem like every night

and then use sleep to work through that problem.

I mean, he’s the first person that I heard

like of the people I really respect that do like what I do,

which is like programming engineering type work,

like using sleep, not accidentally, but with a purpose,

like using sleep.

That’s just basically the difference between,

as you said, a passive approach to it

versus an active deterministic

or hope for a deterministic approach to it.

In other words, that you are actually trying to harness

the power of sleep in a deliberate way

rather than an unthoughtful way.

I still think that mother nature through it,

the 3.6 million years of evolution

has probably got it mostly figured out

in terms of what information should be uploaded at night

and worked through.

I think her algorithm is probably pretty good at this stage.

It’s not to suggest though,

that we can’t try to tweak it and nudge it.

It’s a very light hand on the tiller is what he’s doing.

I don’t think there’s anything wrong with that.

Just like, for example, for me,

fasting has improved my ability to focus deeply

and productivity significantly.

And in that same way,

it’s possible that playing with these ideas

of thinking before bed or some hours before bed

or some playing with different protocols

will have a significant leap

over what mother nature naturally does.

So if you let your body do what it naturally does,

you may not achieve the same level of performance

because mother nature has not designed us

to think deeply about chip design

or programming artificial intelligence systems.

Well, she’s gifted us the architecture

and the capacity to do that.

What we do with that is what life’s experience dictates.

She gives us the blueprint to do many.

Well, if I were to sort of introspect

and self analyze what mother nature wants me to do,

I think given my current lifestyle

that I have food in the fridge

and a bed to sleep on,

I think what mother nature wants me to do is to be lazy.

And so I think I’m actually resisting mother nature

because so many of my needs are satisfied.

And so I have to resist some of the natural forces

of the body and the mind

when I do some of the things I do.

So there’s that dance,

like I’ve been thinking about doing a startup

and that’s obviously going against everything

that my body and mind are telling me to do

because it’s going to be basically suffering.

But the only reason I want…

As you know, it will be over.

Yes, but nevertheless,

there’s some kind of inner drive that wants me to do it.

And then you start to ask a question,

well, how do you optimize the things you can’t optimize

like sleep, like diet,

like the people that you surround yourself with

in order to maximize happiness and performance

and all those kinds of things without also over optimizing.

And that’s such an interesting idea from a engineer.

So as you may know,

you don’t often get those kinds of ideas from engineers.

Engineers usually just don’t read books about sleeping.

They’re usually like the…

They’re not the healthiest of people.

I think that’s changing over time,

especially with Silicon Valley,

especially with the tech sector.

People are starting to understand what’s a healthy lifestyle,

but usually they’re kind of on the insane side,

especially programmers.

But it’s nice to hear somebody like that use sleep

and use some of the things that you talk about

strategically on purpose.

When I get to that idea of not just trying to use

what Mother Nature gave,

but seeing if you can do something more or different,

in a conservative mindset,

I would then pose the question at what cost?

Because when you do something perhaps

that deviates from the typical pre programmed,

you know, Mother Nature’s program,

I suspect it usually comes at the cost of something else.

So maybe he is able to direct and focus

his sleeping cognition on those particular topics

that will gain him better problematic resolution

the next day when he wakes up.

The question is though,

at what cost of the other things that didn’t make it

onto the menu of the finger buffet of sleep that night?

And is it that you don’t process

the emotional difficulties or events,

and therefore you are less emotionally resolved the next day,

but you are more problem resolved the following day.

And so I always try to think,

and I truly don’t want to sound puritanical

either about sleep,

and I think I’ve come off that way many a times,

especially when I started out in the public.

The tone of the book, in some ways,

I look back and think, could I have been a little softer?

And the reason was I was that way back in

when I started writing the book,

which was probably something like 2014 or 15,

sleep was the neglected stepsister

in the health conversation of the day.

And I was just so sad to see the amount of suffering

and disease and sickness that was caused

by insufficient sleep.

And for years before I’d been doing public speaking,

and I’d tell people about the great things

that happen when you get sleep.

People would say, that’s fascinating.

And then they would go back and keep doing the same thing

about not sleeping enough.

And then I realized you can’t really speak

about the good things that happen.

It’s like the news, what bleeds leads.

And if you speak about the alarmingly bad things

that happen, people tend to have a behavioral change.

And so the book as a consequence,

I think probably came out a little bit on the strong side

of trying to convince people.

Well, you were trying to help a lot of people

and that’s a powerful way to help a lot of people.

I was genuinely trying to help people,

but certainly for some people for whom sleep

does not come easy, then it was probably

a tricky book to read too.

And I think I feel more sensitive to those people now

and empathetically connected to them.

So I think the, again, the point was simply

that I don’t mean to sound too puritanical in all of this.

And the same way with caffeine and coffee.

I am just a scientist and I am not here to tell anyone

how to live their life.

That is not my job at all.

And life is to be lived to a degree

and life is to be lived if you want to do a startup.

All I want to do is empower people

with the understanding of the science of sleep.

And then you can make an informed choice

as to how you want to live your life.

And I offer no judgment on how anyone

wishes to live their life.

I just want to try and see if the information

that I have about sleep would alternatively change

how you would think about your life decisions.

And if it doesn’t, no problem.

And if it does, I hope it’s been of use.

Well, maybe this is me trying

to justify my lifestyle to you.

But Dr. Seuss said, you know you’re in love

when you can’t fall asleep because reality

is finally better than your dreams.

I love that quote too.


My sleeping schedule is complicated

and it has to do primarily with the fact

that I love basically everything that I do.

And that love takes a form that may not appear

to be love from the external observer perspective.

Cause it’s often includes struggle.

It often includes something that looks like stress

even though it’s not stress.

It’s like this excitement, it’s this turmoil

and chaos of passion, of struggling with a problem

of being sad and down to the point even depressed

of how difficult the problem is, the disappointment

that the last few weeks and months have been a failure

and self doubt, all that mix.

But I love it.

And a part of that is sometimes staying up all night

working on a thing I’m really passionate about.

And that means sleep schedules that are just like,

you know, sometimes sleeping during the day,

sometimes very often sleeping very little

but taking naps that are like an hour, two hours and so on.

That kind of weird chaos.

And now I’ll also try to give myself back up.

I was trying to like research yesterday

is anybody else productive, wild like this?

And there’s of course a lot of anecdotal evidence

and some of it could be just narratives

that people have told to the public

when in reality they sleep way more.

But there’s a bunch of people that are famous

for not sleeping much.

So on the topic of naps, I read this a long time ago

and I checked this, Churchill was big on big naps.

And is actually just reading more

about Winston Churchill’s sleep schedule

is very much like mine.

So I basically wanna give myself the opportunity

to at night to stay up all night if I want to.

And a good nap is a big part of that in the late evening.

Like I’ll often, this destroys social life completely

but I’ll often take a nap in the late afternoon

or the evening and that sets me

if I want to stay up all night.

And things like that, that I read that Nikola Tesla

slept only two hours a night, Edison the same three hours

but he actually did the polyphasic sleep

like where it’s just a bunch of naps.

What can you say about this madness of love

and passion of loving everything you do

and the chaos of sleep that might result in?

I love the Seuss quote and I’ve had that experience too.

Like you, I adore what I do.

If someone gave you enough money

to live the rest of your life,

got a roof above my head, rice and beans on the table

and they said, you don’t have to work anymore.

I would do nothing different.

I would do exactly, this sounds a little crass

and I hope it doesn’t sound this way

but being a scientist is not what I do, it’s who I am.

And when that’s the case, sleep, working out,

showering and eating are the things that I do

in between my love affair with sleep.

I fell for sleep like a blind roofer.

And it was a love affair that started 20 years ago

and I remain utterly besotted today.

It’s the most beguiling thing in the world to me.

And I could easily and I have, it’s kept me up at night.

When my mind is fizzing with experimental ideas

or I think I’ve got a new hypothesis or theory,

I will struggle with sleep.

I really will, it doesn’t come easy to me

because my mind is just so on fire with those ideas.

So I understand the struggle,

but I couldn’t advocate from a scientific perspective,

the schedule because the science just doesn’t,

I would feel as though I’m doing you a disservice

to say it’s okay, that won’t come with some blast radius,

some health consequences.

You can add Margaret Thatcher and Ronald Reagan

to that list too.

Both of them were very proud chest beaters

of how little sleep that they get.

Thatcher said four hours, Reagan something similar.

And I, knowing the links that we now know

between sleep and Alzheimer’s disease,

I’ve often wondered whether it was coincidental then

that both of them died of the terrible disease of Alzheimer’s

meaning, maybe it doesn’t get you by way of

being popped out of the gene pool in a car accident

because you had a microsleep at the wheel at age 32,

or it doesn’t get you at 42 with heart attack

or even 52 with cancer or a stroke,

maybe it gets you in your seventies.

I think the elastic band of sleep deprivation

can stretch only so far before it snaps

and it ultimately seems to snap.

Nicola Tesla, I think he died of a coronary thrombosis,

I believe.

And there was a wonderful study done out of Harvard

where they took a group of people who had no signs

of cardiovascular disease.

And what they found is that when they track them

for years afterwards, they were completely healthy

to begin with.

Those people who are getting less than six hours of sleep

ended up having a 300% increased risk

of developing calcification of the coronary artery,

which is the major sort of corridor of life for your heart.

When someone says, he died of a massive coronary,

it’s because of a blockade of the coronary artery.

And Tesla passed away from a coronary thrombosis.

We also know that insufficient sleep

is linked to numerous mental health issues.

We know that Churchill had a wicked battle with depression.

Gosh, my goodness, he used to call it black dog

that would come and visit him.

And I think many of his paintings,

he was exquisite painter,

but some of them would depict his darkness

with depression as well.

Edison is interesting.

People have argued that he would short sleep

and he didn’t put much value in sleep.

Whether or not that’s true, we don’t know,

but he was a habitual napper.

You’re right, during the day,

I’ve got some great pictures of him on his inventor’s bench

taking a nap.

And in fact, I believe he set up nap carts around his house

so he could nap.

But what we also know, a study, again,

coming out of Harvard just a couple of months ago,

demonstrated very clearly that polyphasic sleep

is associated with worse physical outcomes,

worse cognitive outcomes,

and especially worse mood outcomes.

So from that sense,

sleeping like a baby is not perfect for adults.

So there’s a fascinating dance here

of the mean and the extreme,

like the average and the high performers.

So I,

this gets to like the meaning of life kind of discussion,

but let’s go that way.

And also happiness.

So when studying sleep and when studying anything

like diet and exercise,

I think you have to really get a lot more data

about individuals to make

conclusive statement.

That’s when people talk about like,

is meat, red meat good for you or bad for you, right?

It’s just so often correlated with other life decisions

when you choose to eat meat or not.

My sense is that whatever life decisions you make,

if they reduce stress and lead to happiness,

that’s also going to be a big boost

that needs to be integrated

into the plots in the science, right?

So I’ll give you an example of somebody

who is unarguably seen as unhealthy.

My friend, Mr. David Goggins.

So he’s clearly, obviously,

almost on purpose destroying his body.

He’s destroying his body and to say

that he’s doing the wrong thing or the unhealthy thing

feels like, feels wrong.

But I’m not sure exactly in which way he feels wrong.

One of the things I’m bothered by,

and again, I apologize for the therapy sessions,

a framework of this,

but I’m bothered by the fact that a lot of people

tell me or David that they’re doing things wrong.

A lot of people in my life, when they see me not sleep,

they’ll tell me to sleep more.

Now they’re correct, but one fundamental aspect

that I’d like to complain about is not enough people,

almost nobody, especially people that care for me,

will come to me and say,

you have a dream, work harder.

It’s like the healthy thing should be a component

of a life well lived, but not everything.

And I don’t know what to do with that

because you certainly don’t want to espouse.

And just like you said, when you were working in your book,

there is a belief, sleep was a secondary citizen

in the full spectrum of what’s a healthy life.

But at the same time, I’m bothered by in Silicon Valley

and all these kinds of work environments

that I get to work with, with engineers,

is there’s to me too much focus on work life balance.

And what that usually starts meaning is like,

yeah, yeah, of course, it’s good to have a social life,

it’s good to have a family,

it’s good to eat well and sleep well,

but we should also discover our passion.

We should also give ourselves a chance

to work our ass off towards a dream

and make mistakes and take big risks

that in the short term seem to sacrifice health.

And I think to come back to how you started

about David Goggins, who I’ve never met,

but who I admire incredibly

and have an immense reverence for the man.

You said two things,

is it wrong to do those things to yourself?

And is it unhealthy to do those things to yourself?

I disagree with the former and I agree with the latter.

So from a health biological medicine perspective,

sleeping in the way that you’ve described

or that other people may be sleeping

in terms of insufficient amounts,

now to your point too about into individual differences,

usually when I see a bar graph and a mean,

I usually say, show me your variance.

I want to see your variance.

In other words, show me the distribution of that effect.

How many people were below the mean?

How many, is it all tightly clustered around this one thing?

So it’s a very robust effect

or was this huge fan of effect where for some people

there was no effect at all and other people

there was a whopping effect and everything in between.

So I don’t discount into individual variability,

but, and I will come back to those two points about,

is it wrong and is it unhealthy in just a second?

When it comes to sleep,

we have found huge amounts of into individual differences

in your response to a lack of sleep.

But one of the fascinating things,

so let’s say that I take you

and we’re going to measure your attention,

your emotion, your mood, your blood pressure,

your blood sugar glucose regulation,

your autonomic nervous system

and your different gene expression.

Let’s say I’m just going to measure a whole kaleidoscope

of different outcomes, brain and body.

And I find that on our measure of cognition

on your attentional ability to focus,

you are very resilient.

You just don’t show any impairment at all

even after being awake for 36 hours straight.

Does that mean that you are resilient

in all of those other domains as well?

The answer is no, you’re not.

So you can be resilient in one,

but very vulnerable in another.

And we’ve not found anyone who isn’t at least vulnerable

in one of those domains,

meaning that it’s somewhat safe to say that

not getting sufficient sleep will lead

to some kind of impairment in any one given individual.

It may not be the same impairment,

but it’s likely to be an impairment.

But to come back to the question,

I think it’s wrong to tell anyone

that it’s wrong to do what they’re doing,

even if they are compromising their sleep,

even if they’re compromising their mental health.

As long as they’re not hurting anyone else,

then I think the answer is

that’s that person’s choice.

Yeah, but that’s that person’s life.

I’d like to push back further.

So see, the way you kind of said it,

yes, you’re absolutely right.

But I would like to say a stronger statement,

which is you should let go of that judgment

of somebody is wrong

and allow yourself to be inspired

by the great heights they have reached.

So take yourself out of the seat of being a judger

of what is healthy or not,

and appreciate the greatness of a particular human.

You watch the Olympics,

the kind of things that some athletes do

to reach the very heights.

The Olympics are taking years off of their life.

They suffer depression after the Olympics often.

The physiology is disastrous.

Everything, their personal life,

there’s their psychology, their physiology,

everything, it’s a giant mess.

So the question is about life.

Healthy now means longevity,

quality of life over a prolonged period of time,

optimum performance over a prolonged period of time.

But to me, beauty is reaching great heights.

And there’s a dance there

that sometimes reaching great heights

requires sacrifice of health

and not like a calculation

where you sat down on a sheet of paper

and say, I’m going to take seven years off my life

for an Olympic gold medal.

No, it requires more chaotic journey

that doesn’t do that kind of calculus.

And I just want to kind of speak to the,

in the culture that struggles of what is healthy and not,

we want to be able to speak to what is healthy

and at the same time be inspired by the great heights

that humans reach no matter how healthy

or unhealthy they live.

Yeah, I agree with that.

I think if that’s a flag you’re hoisting,

I will definitely salute it because it really depends,

what are you trying to optimize for in your life?

And if you are,

I think the only danger potentially with that mindset

is that if you look at many of the studies

of old age and end of life,

most people say I never look back on my life

and wish I worked harder.

I wish instead I’d spent more time with family, friends

and engaged in that aspect.

Now I’m not saying though, coming back to your point,

that that is the standard rubric for everyone.

I don’t believe it is too.

And there are many things that you and I

are both benefiting from today,

even in the field of medicine,

where people have sacrificed their own longevity

for the quest of solving a particular medical problem.

And they died quicker because of their commitment,

because they wished to try and solve that problem

in their pursuit of greatness scientifically.

And I now benefit.

Am I grateful that they did that?

Incredibly grateful.

You know, a simpler demonstration is this.

If tonight at 4 a.m. in the morning,

I have a ruptured appendix, I have an appendicitis,

I am incredibly grateful that there is an emergency team

that will take me to the hospital at 4 a.m. in the morning.

They are awake, they’re not sleeping and they save my life.

And that’s part of what their life’s mission and quest is.

And they saved another’s life by, in some ways,

shaving a little of their own off.

So I don’t take, I have no umbrage

with that mentality at all.

I think you just have to be very clear

about what you’re optimizing for.

And my worry is that most people fall into the rat race

and they never actually ask the question,

why am I doing this?

If you’re just working nine to five or,

and you allow that nine to five to stretch

into much longer, but it’s nevertheless a job

that’s kind of like wears you down.

That’s one thing.

Another thing is when it is like, you’re,

it’s a dream, it’s a life mission.

And for that, I think as long as you know what it is

that you could be doing to yourself

and you are comfortable and A okay with that,

I have no problem with that at all.

Again, as I said, as a scientist, I cannot, should not,

and will not tell anyone what they should do with their life.

All I want you to be able to do is say, okay,

now I understand more about the,

previously these would be known unknowns

and these were the unknown unknowns.

And now I am slightly more cognizant.

I have more knowns than I had before

regarding my sleep and my health,

knowing that information,

do I still choose to make this decision?

And if that’s what I offered,

then I think I’ve done my job.

That’s all I want to offer is just added information

into the decision algorithm.

And what you end up choosing as an output of that algorithm

has nothing to do with me.

It’s not my business and I will never judge anyone for it.

And as I said, I’m immensely grateful for people

who have sacrificed much in their lives

to give me what I have.

So you’re saying as long as the sacrifice sort of grounded

in knowledge of what the sacrifice is,

that sleep is important, all those kinds of things.

And that you’re comfortable with it.

That is, it is your conscious choice

rather than feeling as though you’re trapped

or that you are just, you haven’t thought about it.

And you start that job at age 32

and then you wake up the next morning and you’re 65

and you think, where did my life go?

What was I doing?

That to me, I would feel, I would want to hug you.

And I would say, I’m just, and I’m not saying,

I don’t want to sound belittling here at all.

I would just not wish that for you.

I would wish that you could have thought about

what it was that you’re doing and not have that regret.

Yeah, so I guess I’m, this is for you, the listener.

I’m coming out of the closet here a little bit.

The fact that I enjoy the madness I live in.

So please do not criticize me, embrace me.

I understand the sacrifices I’m making.

I enjoy sleeping on the floor

when I’m passionate programming all night

and just pass out on the carpet.

I love this life.

Okay, so it’s, but it’s definitely something I think about

that there’s a balance, a strike where.

I just want you to have as much of it though.

Of life.

See, quality of life is important.

I should have said,

I want you to have as much high quality life.

And if high quality of life means

I spend five decades on this planet,

but yet in that time, I am thrilled every day.

I’m turned on every day by what I do.

And I reveled in this thing called my life’s work.

I think that that is a 50 year journey

of absolute delight and fulfillment that you should take.

I think about my death all the time.

I meditate on death.

I’m okay to die today.

So to me, longevity is not a significant goal.

I’m so happy to be alive.

I don’t even think it would suck to die today.

I’m as afraid of it today as I will be in 50 years.

I don’t wanna die as much today as I will in 50 years.

There’s of course all these experiences

I would like to have, but everything’s already amazing.

It’s like that Lego movie.

So I don’t know.

So to me, I just wanna keep doing this.

And there’s of course things that could affect,

like you mentioned, dementia and these deterioration

of the mind or the body that can significantly affect

the quality of life.

And so you want to do.

As long as you’re aware of that,

and that’s the price you pay for the entry

into this magical kingdom that you are experiencing,

which is a lovely thing.

I feel privileged too.

I can’t believe the life that I live.

It’s incredible.

And just like you, I think about mortality a great deal.

I think a lot about death, but I don’t worry about death.

I probably, with the exception of the potential pain

that comes before it, that some people,

many people can suffer, that maybe concerns me.

But I actually think about mortality as a tool,

I use it as a lens through which I can then retrospect.

And by placing myself at the point of future mortality,

I can then use it as a retrospective lens

to focus and ask the following question.

Is there anything I feel I would regret

and therefore change in the life that I currently have now?

That’s the way I meditate and use mortality as a question,

is to try and course correct and focus my life.

I worry not about dying,

but I like to think about death

as a way to prioritize my life.

If that makes sense, I don’t know if that makes sense.

No, it makes total sense to decide

how do you want to live today

so that in the future you do not regret

the way you’ve lived today.

Right, and to place yourself in the future

at your point of mortality is one way to, I think,

as an exercise to retrospectively look back

and not lose out on informed choices

that you could otherwise lose out on

if you weren’t thinking about mortality.

Yeah, it clarifies your thinking.

So I mentioned I sleep on the floor,

take naps and power naps, and it’s just kind of madness.

Is there weirdnesses to your own sleep schedule

as a scientist that does incredible work,

has a lot of things going on,

has to lead research, has to write research,

has to be a science communicator,

also have a social life, all those kinds of things.

Is there certain patterns to your own sleep

that you regret or you participate in

that you find you enjoy?

Is there some personal stuff,

quirks or things you’re proud of

that you do in terms of your sleep schedule?

The funny thing about being a sleep researcher

is that it doesn’t make you immune

to the ravages of difficult nights of sleep,

and I have battled my own periods of insomnia in my life too.

And I think I’ve been fortunate in ways

because I know how sleep works

and I know how to combat insomnia.

I know how to get it under control

because insomnia in many ways is a condition

where all of a sudden your sleep controls you

rather than you control your sleep.

Wow, yeah, that’s a beautiful way to put it, yeah.

And I know when I’m starting to lose control

and it’s starting to take control,

and I understand how to regain,

but it doesn’t happen overnight.

It takes a long time.

So you’ve struggled with insomnia in your life?

I have, not all of my life.

I would say I’ve probably had three or four

really severe bouts, and all of them usually triggered

by emotional circumstances, by stress.

Stress that’s connected to actual events in life

or stress that’s unexplainable?

Well, externally triggered.

Yeah, it’s sort of what we would call reactive stress.

And so that’s sort of point number one

about the idiosyncrasies.

The point number two is that when you are having

a difficult night of sleep, as a sleep researcher,

you basically have become the Woody Allen neurotic

of the sleep world.

Because at that moment, I’m trying to fall asleep

and I’m not, and I’m starting to think,

okay, my dorsal lateral prefrontal cortex

is not shutting down.

My noradrenaline is not ramping down.

My sympathetic nervous system

is not giving way to my parasympathetic.

At that point, you are dead in the water

for the next two hours and nothing is bringing you back.

So there is some irony in that too.

I would say for myself though,

if there is something I’m not proud of,

it has been at times railing against my chronotype.

So your chronotype is essentially,

are you a morning type, evening type

or somewhere in between?

And there were times because society

is desperately biased towards the morning types.

This notion of the early bird catches the worm.

Maybe that’s true, but I’ll also tell you

that the second mouse gets the cheese.

Yeah, so I think one of the issues around,

firstly, people don’t really understand chronotype

because I’ll have some people

when I’m sort of out in the public,

they’ll say, look, I struggle with terrible insomnia.

And I’ll ask them, is it problems falling asleep

or staying asleep?

And they’ll say, falling asleep.

And then I’ll say, look, if you are on a desert island

with nothing to wake up for, no responsibilities,

what time would you normally go to bed

and what time would you wake up?

And they would say, I’d probably like to go to bed

about midnight and wake up maybe eight in the morning.

And then I’d say, so what time do you now go to bed?

And they’d say, well, I’ve got to be up for work early.

So I get into bed at 10.

I say, well, you don’t have insomnia.

You have a mismatch between your biological chronotype

and your current sleep schedule.

And when you align those two,

and I was fighting that for some time too,

I’m probably mostly right in the middle.

I am desperately vanilla, unfortunately,

in many aspects of life, but this included,

I’m neither a strong morning type

nor a strong evening type.

So ideally I’d probably like to go to bed around 11,

10.30, 11, probably somewhere between 10.30, 11,

and wake up, I naturally wake up usually most days

before my alarm at 7.04, and it’s 7.04

because why not be idiosyncratic

in terms of setting an alarm?

I love it.

And so I…

That’s kind of awesome.

I’ve never heard about that.

That’s amazing.

I’m gonna start doing that now,

setting alarms like a little bit off the…

Yeah, I know.

I’m never quite sure why we all…

It’s a celebration of uniqueness.

Yeah, and I am quite the odd snowflake in that sense too.

So I would usually then try to force myself

because I had that same mentality

that if I wasn’t up at 6.30 and in the gym by seven

that there was something wrong with me.

And I quickly abandoned that.

But if I look back, if there was a shameful act

that I have around my sleep,

I think it would be that for some years

until I really started to get more detailed into sleep.

And now I have no shame in telling people

that I will probably usually wake up around 6.45 naturally,

sometimes seven when people are looking at me thinking,

you’re a sloth, you’re lazy.

And I don’t finish my daily workout

until I’m not working until probably nine o clock

in the morning thinking, what are you doing?

Now I will work late into the day.

If I could, I would work 16 hours.

It’s my passion just like yours.

So I don’t feel shame around that,

but I have changed my mentality around that.

It’s complicated because I’m probably happiest

going to bed, if I’m being honest, like at 5 a.m.

That’s fine.

You’re just an extreme evening type.

But the problem is it’s not that I’m ashamed for it.

I actually kind of enjoy it because I get to sleep

through all the nonsense of like the morning.

Isn’t that a beautiful thing?

Like people are busy with their emails

and I just am happy as a cow.

And I wake up after all the drama has been resolved.

And cows are happy and the drama has been resolved.


But in society you do, especially,

I mean this is what I think about is

when you work on a larger team,

especially with companies, you are,

everybody’s awake at the same time.

So that’s definitely been a struggle

to try to figure out, just like you said,

how to balance that, how to fit into society

and yet be optimal for your chronotype, you said.

Yeah, you have to sleep in synchrony with it and harmony.

Because normally what we know is that if you fight biology,

you’ll normally lose.

And the way you know you’ve lost is through disease

and sickness.

You said you suffered through several bouts of insomnia.

Is there, aside from embracing your chronotype,

is there advice you can give how to overcome insomnia

from your own experience?

Right now the best method that we have

is something called cognitive behavioral therapy

for insomnia or CBTI for short.

And you work with, for people who don’t know what it is,

you work with a therapist for maybe six weeks

and you can do it online, by the way,

I recommend probably jumping online, it’s just the easiest.

And it will change your beliefs, your habits,

your behaviors and your general stress

around this thing called sleep.

And it is just as effective as sleeping pills

in the short term.

But what’s great is that unlike sleeping pills,

when you stop working with your therapist,

those benefits last for years later.

Whereas when you stop your sleeping pills,

you typically have what’s called rebound insomnia,

where your sleep not only goes back to being

as bad as it was before, it’s usually even worse.

For me, I think I found a number of things effective.

The first is that I had to really address

what was stressful and try to come up with

some degree of meaningful rationality around it.

Because I think one of the things that happens,

there’s something very, talking about conscious states,

to come all the way back to, gosh, I don’t know,

I feel like we’ve only been chatting for like 20 minutes,

but you’re gonna tell me it’s been a while.

Yeah, it’s been a while.

Okay, I’m desperately, I feel terribly sorry.

But let’s come back to conscious states,

which is where we started.

There is something very strange about the night

that thoughts and anxieties are not the same

as they are in the waking day.

They are worse, they are bigger.

And I at least find that I am far

more likely to catastrophize and ruminate

at night about things that when I wake up the next day

in the broad light of day,

I think it’s nowhere near that bad, man.

What were you doing?

It’s not that bad at all.

So to gain firstly, some rational understanding

of my emotional state that’s causing that insomnia

was very helpful.

The second thing was to keep regularity,

just going to bed at the same time waking up.

And here’s an unconventional piece of sleep advice.

After a bad night of sleep, do nothing.

Don’t wake up any later, don’t go to bed any earlier,

don’t nap during the day,

and don’t drink any more coffee than you would otherwise.

Because if you end up sleeping later into the morning,

you’re then not going to be tired

at your normal time at night.

So then you’re gonna get into bed thinking,

well, I had a terrible night of sleep last night.

And yes, I slept in this morning to try and compensate,

but I’m still gonna get to bed at my normal time.

But now you get into bed and you haven’t been awake

for as long as you normally would.

So you’re not as sleepy as you normally would be.

And so now you sit there lying in bed

and it’s another bad night.

And the same thing is, if you go to bed any earlier,

so don’t wake up any later, wake up at the same time,

don’t go to bed any earlier,

because then you’re just probably your chronotype,

your biological rhythm doesn’t want you to be asleep.

And you think, well, it’s a terrible night,

I’m gonna get into bed at 9 p.m.

rather than my standard 10,

I’m just gonna be lying in bed awake for that hour.

Naps will take our double edged sword,

they can have wonderful benefits.

And we’ve done lots of studies on naps

for both the brain and the body.

But they are a double edged sword in the sense that

napping will just take the edge off your sleepiness.

It’s a little bit like a valve on a pressure cooker.

When you nap during the day,

you can take some of that healthy sleepiness

that you’ve been building up during the day.

And for some people, not all people,

but for some people that can then make it harder

for them to fall asleep at night

and then stay asleep soundly across the night.

So the advice would be,

if you’re struggling with sleep at night,

don’t nap during the day.

But if you are not struggling with sleep,

and you can nap regularly, naps are just fine.

And we can play around with optimal durations

depending on what you want.

Just try not to nap too late into the day

because napping late into the day

is like snacking before your main meal.

It just takes the edge off your sleep hunger as it were.

But that would be, so that’s my unconventional

second piece of advice regarding insomnia.

The third is meditation.

I found meditation to be incredibly powerful.

I started reading about meditation

as I was researching that aspect of the book many years ago.

And as a hard nose scientist,

I thought this sounds very woo woo.

This is sort of, we all hold hands and sing come by hour

and everything’s going to be fine with sleep.

I read the data and it was compelling.

I couldn’t ignore it.

And I started meditating and that was six years ago

and I haven’t stopped.

And I find meditation before bed incredibly powerful.

The meditation app companies were perplexed at this at first.

They want people to meditate during the day.

But when they looked at their usage statistics,

they found that they would have people

in the morning meditating.

And then there’s a huge number of people

using the meditation app in the evening.

What they were doing was self medicating their insomnia.

And they finally, rather than railing against it,

they started to see it as a cash cow, rightly so.

So I found meditation to be helpful.

Having a wind down routine

is the other thing that’s critical for me.

I can’t just go from,

because when my mind is switched on

and I think you may be like this too,

if I get into bed, that Rolodex of thoughts

and information and excitement and anxiety and worry

is just whirling away.

And it’s not gonna be a good night for me.

So I have to find a wind down routine.

And that makes sense when you realize what sleep is like.

Sleep is not like a light switch.

Sleep is much more like trying to land a plane.

You know, it takes time to descend down

onto the terra firma that we call sound sleep at night.

And we have this for kids.

You know, I don’t have children,

but you know, a lot of parents will say,

you know, we have to have the bedroom,

sorry, the bedtime routine.

You know, you bathe the kid, you put them in bed,

you read them a story.

You have to go through this routine,

this wind down routine for them.

And then they fall asleep wonderfully.

Why do we abandon that?

As adults, we need that same wind down routine.

So that’s been the other thing

that’s been very helpful to me.

So don’t do anything different.

If you have a bad night of sleep,

keep doing the same thing.

Manage your anxiety, understand it, rationalize it.

Then meditation, and then finally having

some kind of disengagement wind down routine.

Those are the four things that have been very helpful to me.

That’s brilliant.

So the regularities really do a lot of work against insomnia.

Is there,

is it possible to have a healthy sleep life

without the regularities?

I say that because I’m all over the place

and I’ve gotten good at being all over the place.

So I’ll often, like what happens,

I’ll go stretches of time.

There’ll be sometimes a month where I,

my days are like, this is embarrassing to admit,

but they’re like,

just you and I here, just you and I.

It’s like 28 hours or 30 hour days.

Like I’ll just go all the way around

comfortably and happily, I love it.

And then there’ll be a nap.

I mean, if you like add up the hours

when I’m just like sleeping as much as I want,

it’d probably be like six hour average per 24 hours.

Like that kind of, so it works out nicely,

maybe even seven hours, I don’t know.

But that it’s obviously irregular

and there’s chaos in the whole thing.

Like sometimes it’s shorter sleep,

sometimes it’s longer.

Is that totally not a good thing, do you think?

The best evidence that we have to speak to this question

is people who are doing rotating shifts.

And unfortunately the news is not good.

They usually have a higher instance of many diseases

such as depression, diabetes, cardiovascular disease,

obesity, stroke.

And again, that’s just me communicating the data

that we have and I’m not telling you

that you should do anything different.

The other thing is that there’s nothing in your biology

that suggests that that’s how your body was designed

to sleep.

It is a system that loves habit.

You know, if your circadian clock in your brain,

it’s called the suprachiasmatic nucleus,

sits in the middle of your brain, had a personality trait,

it would be a creature of habit.

It loves habit.

That’s how your biology is designed to work

is through very archetypal prototypical expected cycles.

And when we do something different to that,

then you start to see some of the pressure stress fractures

in the system.

But again, to your point, if that’s something

that you don’t mind, you know, adopting and understanding

and then I think you should keep doing

what you’re doing.

Yeah, it’s complicated.

Of course you have to be a student of your own body

and explore it.

One of the reasons I want to have kids

is kids enforce a stricter schedule.

I think I definitely feel that I’m not living

the sort of data wise, scientifically speaking,

the optimal life.

And me just living the way I want to live day to day

is perhaps not the optimal way.

And there’s certain things that I’ve seen

very successful people that I know in my life

when they get, when they have kids,

they actually, the productivity goes up,

they get their shit together.

There’s a lot of aspects that, yeah, the regularity.

I mean, that creatures a habit.

That’s the thing that’s power.

And then you start to optimally use the hours

that you have in the day.

Let me ask you about that.

Well, actually, I just have one quick point on that too.

You know, we often think about sleep as a cost,

but instead I think of sleep as an investment.

And the reason is because your effectiveness

and your efficiency when you’re well slept

typically exceeds that when you’re not.

And to me, it’s the idea of if I’m going to boil

a pot of water, why would I boil it on medium

when I could boil it in half the time on high?

And I sometimes worry that when I speak

to Fortune 500 companies and they’re of this mentality

of longer hours, getting people to rise and grind,

the first point is that after about 20 hours of being awake,

a human being is as cognitively as impaired

as they would be if they were legally drunk.

And the reason I bring that point up

is because I don’t know any company or CEO

who would say, I’ve got this great team,

they’re drunk all the time.

But we often lord the airport warrior

who’s flown through three different time zones

in the past two days, is on email at 2 a.m.

and then is in the office at six.

And I think there is some aspect, not in all people,

but there is sort of some aspect

of that slight sleep machismo.

And that’s not what you are very different.

You are driven by a purity of passion

and a very authentic, incredibly genuine goal

of wanting to do something remarkable with your life.

That’s not the issue I think I’m speaking about.

It’s just simply that I think

maybe this notion of wanting to be awake for longer

to try and get more done can sometimes be at odds

with the fact that you can actually get so much more done

if you’re well slept.

And it’s this trade off.

I actually admire people that take the big risk

and work hard, whether that means staying up late at night,

all those kinds of things,

but it cannot be in the framework,

in the context like what Edison said,

which is sleep feels like a waste of time.

So if you’re not sleeping

because you think sleep is stupid, that’s totally wrong.

But if you’re not sleeping

because you’re deeply passionate about something,

that to me, it’s a gray area, of course,

but that to me is much more admirable.

And everything you’re espousing is saying

whatever the hell you’re doing,

you better be aware that sleep,

long term and short term is really good for you.

So if you’re not sleeping, you’re sacrificing,

just make sure you’re sacrificing for the right thing.

I see vodka and getting drunk the same way.

I know it’s not good for me.

I know I’m not gonna feel good days after.

I know it’s gonna decrease my performance.

And there’s nothing positive about it,

except it introduces chaos in my life

that introduces beautiful experiences

that I would not otherwise have.

It creates this turmoil of social interaction

that ultimately makes me happy

that I’ve experienced them in the moment

and later the stories, you get to meet new people.

It’s like alcohol in this society

is an incredible facilitator of that.

So that’s a good example of not sleeping

and drinking way too much vodka.

Again, it’s this notion of life is to be lived to a degree.

But if you do have children,

I think one of the other things

that then maybe comes into the picture

is the fact that now there are other people

that you have to live for than yourself.

Yeah, but come on, like once they’re old enough,

like if you can’t defend for yourself,

you’re too weak, get stronger.

It’s gonna be that kind of fatherhood.

I got it, I’m understanding so much more

about Lex Freeman than I did before.

That’s why you have to have for me,

that would be my wife would be probably softer.

It’s good cop, bad cop, because I think I’m.

But of course, actually, because I don’t have kids,

I’ve seen some tough dudes when they have kids

become like the softies.

They become like, they do everything for their kids.

It’s become like, it’s totally transforms their life.

I mean, Joe Rogan is an example of that.

I just seen so many tough guys completely become changed

by having kids, which is fascinating to watch

because it just shows you how meaningful having kids is

for a lot of people.

Although I would say having chatted with Joe for some time,

I think he is a delightful,

sweetheart, independent of children.

I think, don’t get me wrong,

I don’t wanna be in a ring with him.

He would face me five ways till Tuesday,

but I think he’s a desperately sweet man

and a very, very smart individual.

Yeah, I mean, but he talks about the compassion he’s gained

from realizing just watching kids grow up

that we were all kids at some point,

you get a new perspective.

I think just like me, I still get this with him.

He’s super competitive and there’s a certain way

to approach life.

You’re striving to do great things

and you’re competitive against others

and that intensity of that aggression,

that can lack compassion sometimes and empathy.

And when you have children, you get a sense like,

oh, everybody was a child at some point,

everybody was a kid.

And you see that whole development process.

It can definitely enrich,

expand your ability to be empathetic.

Let me ask about diet.

So what’s the connection between diet and sleep?

So I do intermittent fasting,

sometimes only one meal a day, sometimes no meals a day.

Is there a good science on the interaction

between fasting and sleep?

We have some data, I would prefer more,

but we have data both on time restricted eating

and then we have some data on fasting to a degree.

On time restricted eating,

I think that it has some benefits,

although the human replication studies

have actually not borne out

quite the same health benefit extent

that the animal studies have.

There’ve been some disappointing studies,

one here close to where we are right now at UCSF recently.

So I think time restricted eating can be a good thing

and there are many benefits of time restricted eating.

Is sleep one of them?

No, it doesn’t seem to be

because there are probably at the time

that we’re recording this,

three pretty decent studies that I’m aware of.

Two out of the three were in obese individuals,

one out of the three were in healthy weight individuals.

And what they found is that time restricted eating

in all three of those studies

didn’t have any advantageous benefit to sleep.

It didn’t necessarily harm sleep,

but it didn’t seem to improve it.

When it comes to fasting though,

which is a different state,

we don’t have too many studies,

experimental studies with longterm fasting.

The best data that we have

is probably from religious practices

and probably the most data we have is during Ramadan

where people will fast for 29 to 30 days

from sunrise to sunset.

And under those conditions,

there are probably five distinct changes that we’ve seen.

None of them seem to be particularly good for sleep.

The first is that the amount of melatonin

that you release, and melatonin is a hormone.

It’s often called the hormone of darkness

or the vampire hormone,

not because it makes you look longingly

at people’s necklines,

but it’s just because it comes out at night.

Melatonin signals to your brain and your body

that it’s dark, it’s nighttime, and it’s time to sleep.

Those individuals,

when they were undergoing that regimen of fasting,

the amount of melatonin that was released

and when it was released,

the amount of melatonin decreased

and when it was released came later.

That was the first thing.

The second thing was that they ended up finding it harder

to fall asleep as quickly as they normally would otherwise.

The third thing was that the total amount of sleep

that they were getting decreased.

The fourth fascinating thing

was that a wake promoting chemical

called orexin increased.

And this is why a lot of people will say,

when I’m fasting, it feels like I can stay awake for longer

and I’m more alert, I’m more active.

And I’ll come back from an evolutionary perspective

why we understand that to be the case.

And then the fourth factor is that fasting

didn’t decrease the amount of deep sleep

that seemed to be unaffected.

It did, however, decrease the amount

of REM sleep or dream sleep.

And we know that REM sleep dreaming

is essential for emotional first aid, mental health,

it’s critical for memory, creativity.

It’s also critical for several hormone functions.

It’s when there’s direct correlations

between testosterone release peaks

just before you go into REM sleep and during REM sleep too.

So REM sleep is critical.

But so those are the five changes that we’ve seen.

None of them seem to be that advantageous for sleep.

But the fourth point that I mentioned,

which was orexin, which is this wake promoting chemical

and a good demonstration or a very sad demonstration

of its power is when it becomes very deficient in the brain

and it leads to a condition called narcolepsy

where you’re just unpredictable with your sleep.

So orexin when it’s in high concentrations

keeps you awake when you lose it.

It can put you very much into a state of narcolepsy

where you’re sleeping a lot of the time

in unpredictable sleep.

Why on earth when you are fasting

would the brain release awake promoting chemical?

And our answer is right now is the following.

One of the few times that I mentioned before

that we see animals undergoing insufficient sleep

or prolonged sleep deprivation

is under conditions of starvation.

And that is an extreme evolutionary pressure.

And at that point, the brain will forgo some.

It won’t forgo all, but it will forgo some of its sleep.

And the reason is so that it can stay awake for longer

because the sign of starvation is saying to the brain,

you can’t find food in your normal foraging perimeter,

you need to stay awake for longer

so you can travel outside of your perimeter

for a further distance

and maybe you will find food and save the organism.

So in other words, when we fast,

it’s giving our brain this evolutionary signal

that you are under conditions of starvation.

So the brain responds by saying, oh my goodness,

I need to release the chemical

that helps the organism stay awake for longer

which is orexin.

So that they can forage for more food.

Now, of course, your brain from an evolutionary perspective

doesn’t know about this thing called Safeway

that you could easily go to and break the fast.

But that’s how we understand fasting.

And I think my dear friend, Peter Attia

has done a lot of work in this area too.

I think fasting and David Sinclair’s brilliant work,

goodness me, what an individual too.

The work is pretty clear there

that time restricted eating and fasting

have wonderful health benefits.

Fasting creates this thing called hormesis,

just like exercise and low level stress

and sauna, heat, shock.

And hormesis is a biological process

I think as David Sinclair has once said,

in simple layman’s terms is,

what doesn’t kill you makes you stronger.

And I think there is certainly good data

that fasting and time restricted eating has many benefits.

Is sleep one of them?

It doesn’t seem to be, it doesn’t seem to enhance sleep.

But it’s interesting to understand its effects on sleep.

I’ve fasted, it’s a study of NF2.

I once fasted 72 hours and another time 48 hours.

And I found that I got much less sleep

and it was very restful though.

I hesitate to say this, but this is how I felt,

which is I needed less sleep.

I wonder if my brain is deceiving me

because it feels like I’m getting

a whole extra amount of focus for free.

And I wonder if there’s longterm impacts of that.

Because if I fast 24 hours,

get the same amount of calories, one meal a day,

there’s a little bit of discomfort.

Like just maybe your body gets a little bit colder.

Maybe there’s just, I mean, hunger.

But the amount of focus is crazy.

And so I wonder, it’s like,

I’m a little suspicious of that.

I feel like I’m getting something for free.

I’m the same way with sweetener,

like a Splendor or something.

It’s like, it’s gotta be really bad for you, right?

Because why is it so tasty, right?

And I think, yeah, as we said before with biology,

if there’s a gain, there’s often a cost too.

But we at least understand the biological basis

of what you’re describing.

It’s not that you actually don’t need less sleep.

It’s that this chemical is present

that forces you more awake.

And so subjectively you feel as though

I don’t need as much sleep because I’m wide awake.

And those two things are quite different.

It’s not as though your sleep need has decreased.

It’s that your brain has hit the overdrive switch,

the overboost switch to say, we need to keep you awake

because food is in short supply.

So you mentioned during sleep, there’s a simulation,

all those kinds of things for learning purposes,

but there’s also these, you mentioned the five ways

in which we become psychotic in dreams.

What do you think dreams are about?

Why do you think we dream?

What place do we go to when we dream?

And why are they useful?

Not just the assimilation aspect,

but just like all the crazy visuals that we get with dreams.

Is there something you can speak to that’s actually useful?

Like why we have such fun experiences in that dream world?

So one of the camps in the sleep field

is that dreams are meaningless,

that they are an epiphenomenal byproduct

of this thing called REM sleep from which dreams come from

as a physiological state.

So the analogy would be, let’s think of a light bulb,

that the reason that you create the apparatus

of a light bulb is to produce this thing called light

in the same way that we’ve evolved

to this thing called REM sleep

to serve whatever functions REM sleep serves.

But it turns out that when you create light in that way,

you also produce something called heat.

It was never the reason that you designed the light bulb,

it’s just what happens when you create light in that way.

And the belief so too was that dreaming

was essentially the heat of the light bulb.

That REM sleep is critical,

but when you have REM sleep with a complex brain like ours,

you also produce this conscious epiphenomenon called dreaming.

I don’t believe that for a second.

And from a simple perspective is that I suspect

that dreaming is more metabolically costly

as a conscious experience than not dreaming.

So you could still have REM sleep,

but absent the conscious experience of dreaming

was probably less metabolically costly.

And whenever mother nature burns the energy unit

called ATP, which is the most valuable thing,

there’s usually a reason for it.

So if it’s more energetically demanding,

then I suspect that there is a function to it.

And we’ve now since discovered that dreams have a function.

The first, as we mentioned, creativity.

The second is that dreams provide a form

of overnight therapy.

Dreaming is a form of emotional first aid.

And it’s during dream sleep at night

that we take these difficult, painful experiences

that we’ve had during the day, sometimes traumatic,

and dream sleep acts almost like a nocturnal soothing balm.

And it sort of just takes the sharp edges

off those difficult, painful experiences

so that you come back the next day

and you feel better about them.

And so I think in that sense, dreaming,

it’s not time that heals all wounds.

It’s time during dream sleep

that provides emotional convalescence.

So dreaming is almost a form of emotional windscreen wipers.

And I think, and by the way, it’s not just that you dream.

It’s what you dream about that also matters.

So for example, scientists have done studies

with learning and memory

where they have people learn a virtual maze.

And what they discovered was that those people

who then dreamed, but dreamed of the maze

were the only ones who, when they woke up,

ended up being better at navigating the maze.

Whereas those people who dreamed,

but didn’t dream about the maze itself,

they were no better at navigating the maze.

So it’s not just that you,

it’s not sort of necessary, but not sufficient.

It’s necessary that you dream,

but it’s not sufficient to produce the benefit.

You have to be dreaming about certain things itself.

And the same is true for mental health.

What we’ve discovered is that people

who are going through a very difficult experience,

a trauma, for example, a very painful divorce,

those people who are dreaming, but dreaming

of that difficult event itself,

they go on to gain resolution

to their clinical depression one year later.

Whereas people who were dreaming just as much,

but not dreaming about the trauma itself,

did not go on to gain as much clinical resolution

to their depression.

So it’s, I think to me, those are the lines of evidence

that tell me dreaming is not epiphenomenal.

And it’s not just about the act of dreaming,

it’s about the content of the dreams,

not just the fact of a dream itself.

It’s, first of all, it’s fascinating.

It makes a lot of sense,

but then immediately takes my mind to,

from an engineering perspective,

how that could be useful in, for example, AI systems of,

if you think about dreaming as an important part

about learning and cognition and filtering previous memories

of what’s important, integrating them.

You know, maybe you can correct me,

but I see dreaming as a kind of simulation of worlds

that are not constrained by physics.

So like you get a chance to take some of your memories,

some of your thoughts, some of your anxieties,

and play with them, like construct virtual worlds

and see how it evolves.

Like to play with those worlds

in a safe environment of your mind, safe in quotes,

because you could probably get into a lot of trouble

with the places your mind will go.

But this definitely is applied in much cruder ways

in artificial intelligence.

So one context in which this is applied

is the process called self play,

which is a reinforcement learning

where agents play against itself or versions of itself.

And it’s all simulated of trying different versions

of themselves and playing against each other

to see what ends up being a good.

The ultimate goal is to learn a function

that represents what is good and what is not good

in terms of how you should act in the world.

You create a set of decision weights based on experience,

and you constantly update those weights

based on ongoing learning.

But the experience is artificially created

versus actual real data.

So it’s a crude approximation of what dreams are,

which is you’re hallucinating a lot of things

to see which things are actually.

No, I think it’s been a theory that’s been put forward,

which is that dreaming is a virtual reality test space

that is largely consequence free.

What an incredible gift to give a conscious mind

to each and every night.

Now the conscious mind, the human mind

is very good at constructing dreams

that are nevertheless useful for you.

Like they’re wild and crazy,

but they’re such that they are still grounded in reality

to a degree where anything you learn in dreams

might be useful in reality.

This is a very difficult thing to do

because it requires a lot of intelligence,

it requires consciousness.

This has been effectively recently being used

in a self supervised learning for computer vision

with the process of what’s called data augmentation.

That’s a very crude version of dreams,

which is you take data and you mess with it

and you start to learn how a picture of a cat

truly represents a cat by messing with it in different ways.

Now the crude methods currently are cropping, rotating,

distorting, all that kind of stuff.

But you can imagine much more complicated

generative processes that start hallucinating different cats

in order for you to understand deeply of what it means

for something to look like a cat.

What is the prototype of a archetype of a cat?

Yeah, the archetype.

I mean, that’s a very difficult process for computer vision

to go from what are the pixels

that are usually associated with a cat

to like, what is a cat in the visual space?

In the three dimensional visual spaces projected on an image,

on a two dimensional image, what is a cat?

Those are like fundamentally philosophical questions

that we humans don’t know the answer to,

like linguistically.

But when we look at a picture of a cat and a dog,

we can usually tell pretty damn well what’s the difference.

And I don’t know what that is because you can’t reduce that

to pointy ears or non pointy ears,

furry or not furry, something about the eyes.

It’s been a long standing issue in cognitive science,

cognitive neuroscience too,

is how does the brain create an archetype?

How does it create schemas that have general applicability,

but yet still obtain specificity?

That’s a very difficult challenge.

I mean, we can do it, we do it.

It’s rather bloody amazing.

And it seems like part of the toolbox

is this controlled hallucination, which is dreams.

Well, it’s a relaxing of the rigid constraints.

I often think of dreaming as,

it’s from an information processing standpoint,

the prison guards are away

and the prisoners are running a mock in a delightful way.

And part of the reason is because when you go

into dream sleep, the rational part of your brain

called the prefrontal cortex, which is the part,

it’s like the CEO of the brain.

It’s very good at making high level, rational,

top down decisions and controlled actions.

That part of the brain is shut down during REM sleep.

But then emotional centers, memory centers,

visual centers, motoric centers,

all of those centers actually become more active.

In fact, some of them are more active

than when we’re awake in the dream state.

That’s fascinating.

So your brain from a neural architecture perspective

is radically different.

Its network feature is not the same as wakefulness.

And I think this is an immensely beneficial thing

that we have at least two different rational

and irrational conscious states

that we do information processing in.

The rational, the veritical,

the page one of the Google search is wakefulness.

The more irrational, illogical, hyper associative

Google page 20 is the REM sleep.

Both I think are critical, both are necessary.

That’s fascinating.

And again, fascinating to see how that could be integrated

in the machines to help them learn better

and to reason better.

And in some ways we also know it

from a chemical perspective too.

When you go into dream sleep,

it is a neurochemical cocktail like no other

that we see at the rest of the 24 hour state.

There is a chemical called noradrenaline

or norepinephrine in the brain.

And you know of its sister chemical

in the body called adrenaline.

But upstairs in the brain, noradrenaline

is very good at creating a very hyper focused,

attentive, narrow, it’s sort of very convergent way

of thinking to a point, sharp focus, that’s the only thing.

The spotlight of consciousness is very narrow.

That’s noradrenaline.

When you remove noradrenaline,

then you go from a high SNR, a high signal to noise ratio

where it’s just you and I in this moment,

I don’t even know what’s going on elsewhere.

I am with you, noradrenaline is present.

But when you go into REM sleep,

it is the only time during the 24 hour period

where your brain is devoid of any noradrenaline,

it is completely shut off.

And so the signal to noise ratio is very different.

It’s almost as though we’re injecting

a greater amount of noise into the neural architecture

of the brain during dream sleep,

as if it’s chemically brute forced

into this relaxed associative memory processing state.

And then from an anatomical perspective,

just as I described, the prefrontal cortex goes down

and other regions light up.

So it is a state that seems to be very,

I mean, if you were to show me a brain scan of REM sleep

and tell me that it’s not REM sleep,

just say, look, based on the pattern of this brain activity,

what would you say is going on in this person’s mind?

I would say, well, they’re probably not rational.

They’re probably not having logical thought

because their prefrontal cortex is down.

They’re probably feeling very emotional

because their amygdala is active,

which is an emotional center of the brain.

They’re definitely going to be thinking visually

because the back of the brain is lit up, the visual cortex.

It’s probably going to be filled with past experience

and autobiographical memories

because their memory centers are lighting up.

And there’s probably going to be movement

because their motor cortex is very active.

That to me sounds very much like a dream.

And that’s exactly what we see in brain scanners

when we’ve put people inside of them.

One of the things I notice sleep affects

is my ability to see the beauty in the world.

So what do you think is the connection

between sleep and your emotional life,

your ability to love other human beings and love life?

Yeah, I think it’s very powerful and strong.

So we’ve done a lot of work in the field

of sleep and emotion and sleep and moods.

And you can separate your emotions into two main buckets,

positive and negative.

And what’s interesting is that when you are sleep deprived

and the more hours that you go into being awake

and the fewer hours that you’ve had to sleep,

your negative mood starts to increase.

And we know which individual types

of emotions are changing.

I’ve got a wonderful postdoc in my lab

called Etty Ben Simon, who’s doing some incredible work

on trying to understand the emotional,

individual emotional tapestry of affective,

meltdown when you’re not getting sufficient sleep.

But let’s just keep with two dimensions,

positive and negative.


Most people would think, well, it’s the negative

that takes the biggest hit when I’m sleep deprived.

It’s not.

By probably in a log order, magnitude larger

is a hit on your positive emotions.

In other words, you stop being sleep deprived

of positive emotions, in other words, you stop gaining

pleasure from normally pleasurable things.

And it’s a state that we call anhedonia.

And anhedonia is the state that we often call depression.

So depression to most people’s surprise isn’t necessarily

that you’re always feeling negative emotions.

It’s often more about the fact that you lose the pleasure

in the good things in life.

That’s what we call anhedonia.

That’s what we see in sleep, an insufficient sleep.

And it happens quite quickly.

Yeah, it’s kind of fascinating.

I think I do, it’s not depression,

but like it’s a stroll into that direction,

which is when I’m sleep deprived,

I stop being able to see the meaning in life.

The things that gave me meanings starts to lose meaning.

Like it makes me realize how enjoyable everything is

in my life because when I start to lose it,

when I’m severely sleep deprived,

you start to see how much life sucks when you lose it.

But that said, I’m just cognizant enough

that sleep fixes all of that.

So I use those states for what they’re worth.

In fact, I personally like to pay attention to the things

that bother me in doing that time.

Cause they also reveal important information to me.

That’s interesting.

I have to use like a Rorschach to, yeah.

I mean, there’s, so I find this when I fast combine

with sleep deprivation, I’m clear to see with people,

clear and identifying the things

that are not going right in my life

or people that I’m working with are not doing

as good of a job as they could be doing.

Like people that are negative in my life,

I’m more able to identify them.

So I don’t act on that.

It’s a very bad time to act on those decisions,

but I’m like recording that information

because I usually, when I’m well rested and happy,

I see the beauty in everybody,

which can get you into trouble.

So you have to balance those two things.

But yes, it’s fascinating.

But there’s irony there too, which is the fact that,

you know, when you’re well rested and well slept,

just as you said, you see the beauty in life

and it sort of enlivens you

and sort of gives you a quality of life

that’s emotionally very different.

Yet then we are contrasting that against the need

for not getting enough sleep

because of the beautiful things

that you want to accomplish in life.

And I don’t actually see them as,

you know, sort of completely counterintuitive

or paradoxical because I still think that you can strive

for all of the brilliant things that you are striving for,

to have the monumental goals,

the Herculean challenges that you wish to take on and solve.

They can still enthrall you and excite you

and stimulate you.

But because of the insufficient sleep that they can

or that goal can produce,

it will shave off the beauty of life

that you experience in between.

And again, this is just about the trade off.

I will say though that,

and this is not applicable to your circumstance,

we do know that insufficient sleep

is very strongly linked to suicide ideation,

suicide attempts and tragically suicide completion as well.

And in fact, in 20 years of studying sleep,

we have not been able to discover

a single psychiatric condition in which sleep is normal.

And I think that that is a profound,

I think it tells us so much about the role of sleep

as a potential causal agent in psychiatric conditions.

I also think it’s a potential sign

that we should be using sleep as a tool

for the prevention of grave mental illness.

Yeah, it’s both a cause and a solution.

So yeah, I mean, me personally,

I’ve gone through a few dark periods quite recently

and it was almost always sleep is not the cause,

but sleep is the catalyst from going to a bad time

to a very bad time.


And so it’s definitely true.

And it’s funny how sleep can just cure all of that.

There’s actually a beautiful quote

by an American entrepreneur called E. Joseph Kosman,

who once said that the best bridge

between despair and hope is a good night’s sleep.

And I spilled quite so much ink and hundreds of pages

in elegantly trying to say the same thing in my book.

And he said it in one line and it’s beautiful.

What do you think is,

we’ve been talking about how to extend this life,

how to make it a good life.

We’ve been talking about love.

What do you think is the meaning of this whole ride?

Of life?

Of life.

Why do we wanna make it a good one?

Do you think there’s a meaning?

Do you think there’s a answer to the why?

For me personally,

I think the meaning of life is to eat,

is to sleep, is to fall in love, is to cry,

and then to die.

Oh, and probably race cars in between.

Race cars.

Well, there’s a whole topic of sex we didn’t talk about.

So that’s probably in there.

Should we do that?

Maybe if you’ll have me back, I would love to do.

I will go around to.

Next time we will do another three hours on sex alone.

Has it been?


It has been over three hours.

Gosh, okay.

Matt, I’m a big fan of your work.

I think you’re doing really important work.

Even despite all the things I’ve been saying

about the madness of my own sleep schedule,

I think you’re helping millions of people.

So it’s an honor that you spend your valuable time with me

and I can’t wait until your podcast comes out.

I’m a huge fan of podcasts, I’m a huge fan of you,

and it’s just an honor to know you

and to get a chance, hopefully in the future,

to work together with you.

You’re a brilliant man and you’re doing amazing things.

And I feel immensely honored to have met you,

to now know you, and to start calling you a friend.

Thank you for what you do for the world

and for me included.

Thank you, Matt.

Take care.

Thanks for listening to this conversation with Matt Walker

and thank you to Stamps.com, Squarespace,

Letter Greens, BetterHelp, and Onnit.

Check them out in the description to support this podcast.

And now, let me leave you with some words

from Nikola Tesla, who we discussed in this podcast

as sleeping very few hours a night.

All that was great in the past was ridiculed,

condemned, combated, and suppressed,

only to emerge all the more powerfully,

all the more triumphantly from the struggle.

Thank you for listening and hope to see you next time.

comments powered by Disqus