Kind: captions
Language: en
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
hubermann 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 better help and on it
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 on to
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 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 lex friedman podcast and
here is my conversation with matt walker
you should try these shades on and see
what you look like
so they are now your shades
and that's not the question it's the
same thing as uh putin took the super
bowl ring and it's now his ring
[Laughter]
yeah one wonders if he was offered it
but um they are yours
[Laughter]
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
you know 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 you know 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 uh 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'm a
social leper but
and i started to realize that some parts
of the brain were
um 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
kafka 20 years ago um
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
occur 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 all right you know
we eat to cure hunger yeah 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 now
so far the answer seems to be no
so why
why does the body and the mind
crave sleep then why do we sleep
how you know
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 the third one is during
migration when birds are flying trans
oceanographic to 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's 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
sleeping 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 uh physiologically or
psychologically the 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 by 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 you know what are the pluripotent
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 yeah you know 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
you know maybe like some kind of
predator predator-prey relationships
yeah but you're saying 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 and you know there was
an energy conservation hypothesis for a
while which is that we need to
essentially go into low battery mode you
know 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 know you just go out and club
another baby seal or whatever it was and
you wouldn't worry you know so it has to
be much more to it than energy
conservation much more to it than
sharing you know ecosystem space and
time much more to it than simply
predator prey relationships
if sleep really did and
you know looking back even very old
evolutionary organisms like earthworms
millions of years old they have periods
where they're active in periods where
they're passively asleep it's called
lethargics
and so
what that
in some way suggested to me was
sleep evolved with life itself on it
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 um 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 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
awake awakenness
and how many conscious states are there
so when you're intuit your 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
really three main 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 i you know
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 day dreams than we are
when we are as we are now together
present and
extraceptively focused rather than
intraceptively 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 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
micro sleeps 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
micro sleep 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 micro sleeps
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 yeah
so i've for
for uh
five six years at mit
really focused on this
human side of driving question and one
of the big concerns is
the
micro sleeps 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 uh drowsiness is it
possible to detect these kind of micro
sleeps or actually just sleep in general
um
among other things like distraction
these are all words that have so many
meanings and so many debates like
like attention is a whole nother one
just because you're looking 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
um so i i wonder if you could say
something to
uh you know they say the eyes or the
windows to the soul do you think um
the eyes can reveal
something about uh
sleepiness uh through uh through
computer vision through
just looking at the video of the face
and andrew huberman and i your friend
have talked about this so we'd love to
work on this uh together so you should
do it it's a fascinating problem but
drowsiness is a tricky one so there's
what kind of information
there's uh blinking and there's eye
movement
and those are the ones that can be
picked uh 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 um you know
aperture of i so in other words partial
closures foreclosures
duration of those closures duration of
those partial closures of the eyelid
um i think there may be some information
in the pupil as well
because as we're transitioning between
those states change 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
the
it's time for them to kick in some
manufacturers auto manufacturers sort of
have something
beta version maybe an alpha version of
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
uh 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
the primary signal that they're
comfortable using is the steering wheel
reversals so 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 yeah that's a
sign of like you starting to drift into
micro sleep i think that's a very very
crude signal it's probably a powerful
one there's a whole other component to
this which is
it seems like it's so driver and
subject-dependent
the
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 uh the
searches for like universal signals that
are pretty damn good for like ninety
percent 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
ten of them you know 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 that'd
be amazing understands when you are well
slept yeah 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 patent 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 the savile
row suit of sleepiness features you know
that would be my if you want to ask me
about moonshots and crazy ideas that's
where i go but to start with i think
your approaches 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
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
the 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
is uh
and uh the human factors community
which is this community that one of the
big things they study
is uh 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 micro sleeps 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
they get drowsy and lose vigilance much
much faster
the really surprising thing with tesla
autopilot it was surprising to me it's
surprising to uh the human factors
community and in fact they still argue
with me about it is uh it seems that
humans
in tesla's with autopilot
and other similar systems are not
becoming less vigilant
at least
the with with the studies we've done so
there's something about the urgency of
driving
i can't i'm not sure the 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 what 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
uh 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 um so there needs to
be that dance of inter interaction
of a human and machine
but currently it's mostly uh steering
wheel based so
you know this this idea that your hands
should be on the on the steering wheel
that's
uh a sign that you're paying attention
is um isn't outdated and a very crude
metric i agree
yeah i think there are far more
sophisticated ways that we can solve
that problem
uh if we invest
big philosophical question
before we get into fun details um
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 the hard question of consciousness
that it feels like something
to be us
is that like a nice little feature like
a like a like a quark of our mind or is
it somehow fundamental because sleep
feels like we take 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 know you've risen above your
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 you know when you slept last
night which i know um may have been
perhaps a little less than than me but
when you went into dreaming you know 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 um 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 had to
experience any one of those five things
while you're awake you would probably be
seeking psychological help
but what so i placed 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 you know 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 can
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
manicled is this your sense of conscious
self yeah that's a strong sign that
consciousness is fundamental to the
human mind
um or we're just creatures of habit
we've gotten used to having
consciousness maybe it just takes a lot
of uh
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
yeah well the same thing is true
for
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 escaped
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 that
it's quite useful to have consciousness
for uh 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 uh
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 can 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 uh like to to 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 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 and
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
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 complementary more orthogonal
[Music]
so i'm sometimes
perplexed that people are trying to
mimic human consciousness rather than
think about creating
something that's different yeah i think
of human consciousness or consciousness
in general is this magic
um
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
uh 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 um
human to robot connection the same way
human to dog a human to cat connection
that there's a there's a 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
uh 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 and more than that everything we'll
do
will be silly 100 years from now but
it's still a war 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 as freedom and
uh
and i that's how i see that t-shirt
please
i love that so i and you know the human
robot interaction is fascinating because
it's like it's like watching dancing
i've been uh
dancing tango recently and just it's
like there is no goal the goal is to
create something magical
and uh
whether consciousness or emotion or
elegance of movement all of those things
uh aid in the creation of the magic and
it's a free it's an art form to explore
how how to make that um
how to create that in a way that's
compelling yeah i love that 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 uh well first the second time i
talked to joe rogan on his podcast
i said we got into this heated argument
about whether a
sensible woman is a better movie than
john wick
because it's one of my favorite movies
for many reasons one is for sensible
women some scent of a woman uh partially
know that by the way it's just you just
yeah i don't know if you would actually
know of awesome awesome yeah yeah i said
i love the tango scene i love al
pacino's performance
it's a wonderful movie
then joe joe was saying john wick is
better so we to this day argue about
this i think it depends in on what
conscious state you're in yes that you
would be ready and receptive to but um
sense of 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
the younger
yeah i
uh
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
um
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 uh what is it
lieutenant colonel or whatever he was
coming
yeah
come in uh 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
um
awkward sort of huge grand gene it's
it's very very
at the opposite end of the spectrum of
the remarkable feat of uh al pacino at
the end of that scene but um and yeah
integrity is um it's a
challenging
thing and i value it much and i think
um
it can take 20 years to build a
reputation in two minutes to lose it and
there is nothing more that i value than
but 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
um
you know that's what being in some ways
a scientist is you're
you're just driven by truth and the
irony relative to something like
mathematics is that in science you never
find truth what all you do in science is
you discount the things that are likely
to be untrue
leaving only the possibility of what
could be true yeah 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 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 on a
scientist one is like funding sources
yeah i've noticed this that um 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 uh i don't care how much
money billions or trillions
the
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 uh you know for a couple of decades
publishing an idea
um
and then realizing at some point that
that idea was wrong all along right and
that 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
um
that doesn't have to be in some big
dramatic way it could be in a bunch of
tiny ways along the way right
like uh reconfigure your intuition about
a particular
uh problem
that's and all of that is integrity when
everybody in the room
uh you know believes a certain thing
everybody in the community believes a
certain thing
to uh 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 you know 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 i kind of like that i
always like that combination i have the
same i'm like very self-critical
imposter syndrome all those things
uh 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 to drive to be better like thinking
yourself is not that great and always
driving to be better and at the same
time because that's 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 that 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 uh
of me on the internet
so i think i think i just naturally lean
into the things i'm afraid of and i'm
uncomfortable doing yeah like i'm very
afraid of talking to people and you know
just even
before talking to you today just a lot
of anxiety anxiety and all those kinds
of things about talking to me yeah yeah
oh
nervousness
uh fear in some cases uh self-doubt and
all those kinds of things
but i do it anyway so the reason i bring
that up is um
you've uh 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 your to that question
like you i am always more afraid of not
trying than trying
yeah
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
um
the podcast is a little bit different
than this format it's are going to be
short form monologues
from yours truly uh 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 uh
your friend mine andrew huberman
is does he he's an incredible human
being okay 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 anything
he's that magnificent of a human being
when i talk to him in like in person
he always generates intelligent words
well cited non-stop 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
i wouldn't have um
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 because i thought there's no way you
could do what you're doing
because it's a lot of work uh but he is
like
doing an incredible job of it i just
think
it's the same with like dan carlin in
hardcore history i thought
i thought that the way andrew's doing it
would crush him the way
he 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 that
can be overwhelming now andrew seems to
be just plowing through anyway if
there's mistakes he'll he'll say there's
corrections and so on yeah 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
two a week
of just non-stop dropping knowledge
any one sentence of which could be
totally wrong it could be a mistake and
there will be yeah mistakes you know and
i you know in the first edition of my
book there were errors that you know we
corrected in the second edition too
but
there will be probabilistically you know
if you've got you know 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
the reverence of
um
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 like it's a cool group of like
scientific people that uh i'm fortunate
enough to not be interacting with this
is you and andrew and um 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 a 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
it's it's a really exciting medium to me
and it's cool that there's this like
group of people that uh
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 it wonder it'd be too much
is the answer to that like
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 yeah but i will
persist
look can i ask you some detailed stuff
you mentioned that goodness go anywhere
you wish with sleep uh so
i'm a big fan of coffee and caffeine
and i've been
especially 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
um
it feels like more like a ritual then 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 just consuming huge
amounts of caffeine all that to say
uh
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
um the health benefits associated with
drinking coffee are
really quite well established now
um
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
you know 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
but 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 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 like 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 light 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 percent of your deep sleep if you
drink caffeine in the evening
so to give you some context to 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 you know the goldilocks syndrome not
too little not too much just the right
amount
the second component is the timing
though caffeine has a half-life of about
five to six hours
meaning that after five to six hours
fifty percent 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 you know even
two cups of coffee in the morning
i 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 cyp
1 a 2
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 um
have a version of that gene that is not
very effective at clearing out the uh
the caffeine and therefore the half-life
sort of sensitivity could be somewhere
between you know eight to nine hours
so we understand that there are
individual differences but overall i
guess the
top line here is
drink coffee um 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's
it's like a muscle
in terms of the
all the combination of letters and
numbers that you just said is there some
aspect that if um
i can improve
the quarter life the half-life
can decrease that number if i just
practice
like i drink a lot of coffee so like
habit
alters how your body is 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 you know 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 where's
you know this there's a lot of
stimulation going on this is too much so
i'm just going to
when normally i would you know 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 equilibriated 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 you know
drugs of abuse things like heroin when
people go into abstinence
you know 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
you know 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 is 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
yeah or is this advice kind of
impossible because there's so much
variability there is a huge variability
and i think everyone themselves you know
to a degree knows it although i'll put a
caveat on that too because it's 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 you know before so
assuming a normative bedtime in society
i would say try to stop drinking
caffeine you know
before 2 pm and
just keep an eye out you know 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 as you just mentioned is that
sleep before learning will essentially
prepare your brain
almost like a dry sponge ready to sort
of
initially soak up new inform