26__transcript.txt

ANDREW HUBERMAN: Welcome to
the Huberman Lab podcast,
where we discuss science
and science-based tools
for everyday life.
[MUSIC PLAYING]
I'm Andrew Huberman,
and I'm a professor
of Neurobiology
and Ophthalmology
at Stanford School of Medicine.
Today we are
discussing caffeine.
Caffeine is one of the
most widely used substances
on the planet.
Estimates are that more than
90% of adults and as many as 50%
of kids that is
adolescents and teenagers
use caffeine on a daily basis.
Caffeine is an amazing molecule.
Most people are familiar
with caffeine's ability
to increase alertness and
to reduce our feelings
of sleepiness and fatigue.
And indeed, it does that.
But what most people
are not aware of
is that caffeine acts
as a strong reinforcer.
What I mean by reinforcer
is that, when caffeine
is present in a drink or food--
and yes, indeed, caffeine
is present in many foods
even unbeknownst to us.
When it's present
in drinks and foods,
we actively come to like those
foods and drinks more than
if caffeine were not contained
in those foods and drinks.
So it reinforces our liking of
particular foods and drinks.
And indeed, it even
reinforces our liking
of the containers
they are consumed from
and the company we keep when we
consume foods and drinks that
contain caffeine.
That is, caffeine is
not just a stimulant.
Caffeine is a reinforcer.
And it's a reinforcer that
plays an active role in almost
everybody's daily life.
We can say that with confidence
because, as I mentioned
a moment ago, more than 90% of
people are consuming caffeine.
And most people think that they
consume caffeine because it
makes them feel more alert.
But there are many reasons
why you're consuming caffeine.
And I'm not going to tell you
that consuming caffeine is
necessarily bad.
In fact, today, I'm going
to tell you about many
of the positive health
benefits of caffeine,
including
neuroprotective effects,
antidepressive
effects, and certainly
performance-enhancing effects,
both for mental performance
and for physical performance.
Now that said, there are
certain situations in which you
want to avoid caffeine, and
there are certain people who
might opt to avoid caffeine.
That's especially the case
when one thinks about caffeine
not just as a stimulant
but as a reinforcer.
In fact, caffeine is
such a strong reinforcer
that, if even tiny
amounts of caffeine
are present in certain
foods and drinks,
you will very quickly
come to prefer those foods
and drinks over
other choices, which
can be a good thing
or a bad thing,
depending on what sorts
of food and drink choices
you're trying to make.
So today, I'm
going to inform you
about how caffeine works
at a mechanistic level.
I promise to do
that with a minimum
of nomenclature and such
that, even if you don't have
a background in
biology, you will
be able to digest that
information easily.
And then I'll tell you how to
use caffeine to your advantage
or conversely how to avoid
caffeine at certain times
to your advantage.
So today's episode will focus
both on mechanisms and tools
that is the use and
leverage of caffeine
to improve mental
health, physical health,
and performance.
Before we go any further
into today's discussion,
I want to tell you about some
recent results about a molecule
that's found in certain
caffeinated beverages
and that has been proven to
be very useful for both weight
loss, mental performance, and
controlling blood sugar levels.
And that's GLP-1 or
glucagon-like peptide 1.
Glucagon-like peptide 1 is
found in the brain and body.
It acts both on
the brain and body.
It does many different things.
But one of its primary
effects that's been discovered
is to reduce hunger.
And it does that in two ways.
It does that by
activating certain neurons
in your hypothalamus.
So that's a brain region that
controls hunger and satiety.
It makes us feel full at
the level of the brain,
so it makes us feel
sated, that is.
And it actually
makes us feel full.
It turns out that GLP-1 acts
on certain receptors in the gut
to make us feel as if
we've ingested enough food.
It doesn't necessarily
make us feel
as if our gut is distended,
but it makes us feel full.
That's really interesting
because, if you
think about it, when we eat,
our stomach fills up, obviously.
And that information has to be
communicated to the brain such
that the brain can then send
satiety signals that actually
shut off our hunger.
And believe it or not,
the brain actually
activates signals
to reduce the desire
to chew when our
stomach is full.
And GLP-1, as I mentioned,
works on the brain
to create these feelings of
satiety as if we've had enough
and to reduce our
desire to eat more.
And GLP-1 acts
directly on the gut
to give us a slight sense of
fullness in the gut, which then
is communicated to the brain.
So really, there are
two parallel signals
being sent when we have
GLP-1 present in our system.
Now a little bit of
relevant history on GLP-1.
It was actually discovered
in Gila monsters.
These are these reptiles that
can go long periods of time
without eating.
And a very clever
scientist decided
to study why it is that certain
animals like Gila monsters
can go a long period of time
without ingesting anything.
And it's because they produce
very large amounts of GLP-1.
They isolate the
peptide from GLP-1,
then they looked for the
analogous peptide in humans.
And it turns out
that does exist.
And as I mentioned, it's
released in both brain and body
to make you feel full and sated.
Why am I telling you all this?
Well, today we're going
to talk about caffeine.
And there's one particular
caffeine source,
which is yerba maté, and there
are some other forms of teas
similar to yerba mate that
stimulate the release of GLP-1
significantly.
There are also nowadays drugs
which are called analogues
of GLP-1.
So these are drugs
that mimic or are
identical to the kind of
GLP-1 that you would make.
And those drugs are proven
to be very effective
for the treatment of
certain forms of diabetes
and for the
treatment of obesity,
but they trigger
enormous amounts
of GLP-1 pathway activation.
So those are extreme cases
for people that are really
struggling for weight loss.
But the clinical trials and
the data that are out there
in the general
population now are very,
very promising for
GLP-1 analogues.
Yerba maté tea, provided
it's not the smoked variety--
and I mention that because a
number of people have cued me
to the fact that yerba maté
teas come in smoked varieties
and nonsmoked varieties.
And the smoked
varieties are thought
to perhaps be carcinogenic.
That is, procancer-causing.
So I advise people to avoid
smoked varieties of yerba maté
tea.
But yerba maté teas are known
to stimulate significant amounts
of GLP-1 release.
And so they can be effective
as a weight loss tool,
mainly by blunting appetite.
And again, they do that both
at the level of the brain
and at the level of the gut.
Now all of what I
just told you has
been known for some
period of time,
but there are new set of
findings that were just
published in Cell Reports
Medicine, Cell Press
journal, excellent journal--
which indicate exactly
how it is that GLP-1
stimulates both satiety and
can trigger additional weight
loss through other mechanisms.
And I find the mechanism to be
really interesting and actually
really important, given
some other topics we've
covered on this podcast before.
So the basic finding
is that GLP-1,
whether or not it's stimulated
through the release of analogue
drug that one is prescribed
or by drinking yerba maté tea,
for instance, and stimulate
release of your own so-called
endogenous GLP-1, yes, it makes
you feel more full at the level
of brain and body.
But it turns out it also
stimulates thermogenesis.
Now thermogenesis is
the active utilization
of more metabolic energy.
And fat cells, in particular--
so-called beige and brown fat
cells--
are a potent source of
thermogenic activity
in your body.
The basic background is that
you have white adipose cells, so
white fat cells.
You have beige fat cells,
and you have brown fat cells.
And the beige and brown
ones are fat cells
that you actually want more of.
They are not abundant
under your skin.
They're abundant really
around your clavicles
and your upper neck.
They are the ones
that generate heat.
And the beige and
brownness of them
is actually the consequence of
having a lot of mitochondria
in those cells.
When GLP-1 is elevated
in your system,
it turns out that
it communicates
to those white fat cells
and helps convert them
into beige and brown fat cells.
That is, it takes fat
cells that are not
doing anything useful for you
except being stored energy.
And I think most
people out there
would like to have fewer of
those white adipose cells.
There are few of you
out there that actually
need more of them that
are too thin, too lean,
but most people are suffering
from having too many
of these white adipose cells.
Well, when you ingest yerba maté
tea or you were to take a GLP-1
analogue or stimulate GLP-1 in
any number of different ways,
yes, you stimulate
increased satiety,
but you're also stimulating the
conversion of these white fat
cells into beige
and brown fat cells,
which makes you more thermogenic
and over time raises your basal
metabolic rate.
So you're burning more
calories even at rest.
It also makes you
feel as if you're
more comfortable in colder
environments at rest.
This is very much the same
as the mechanism that's
induced when you were to,
say, take a cold shower
or do regular ice baths or
get into cold water regularly.
That, too, stimulates the
conversion of white fat cells
to beige and brown fat cells.
So I like these
findings very much
because they provide a
mechanistic coherence.
They provide that is a
really nice story as to how
something like GLP-1 could be
so effective for weight loss.
Yes, on the one hand,
GLP-1 is reducing appetite,
and that, of course, will help
people maintain or lose weight.
But it's also increasing
basal metabolic rate.
And we now know how
that's accomplished.
It's likely accomplished
at least through this one
mechanism by the
stimulation of conversion
of these white fat cells,
which don't do much for us
except as energy storage
units to these metabolically
mitochondrial-rich beige
and brown fat cells,
which you can think of as
sort of the oil in the candle
that allows your furnace, your
metabolism to burn at a higher
temperature and a higher rate.
So that's the mechanism.
And the basic tool
takeaway is that,
if you are somebody who's
interested in losing weight
and you want to leverage
the GLP-1 pathway,
drinking a cup or two of yerba
maté tea early in the day would
be a great way to
stimulate GLP-1 release.
There are other ways to
stimulate GLP-1 release.
You can get it through
certain forms of exercise.
In particular, fasted exercise.
This is actually a vote in
favor of fasted exercise.
There's a debate as
to whether or not
fasted cardio burns more
fat than nonfasted cardio.
And the data basically say
no, it doesn't really matter.
But that doesn't really
take into account
the longer arc of things
like GLP-1 release,
so that needs to be
taken into consideration.
So you could do fasted cardio.
You could drink yerba maté tea,
keeping in mind that yerba maté
tea does contain caffeine.
We'll talk more about the
specific forms of stimulants
including caffeine
that maté has.
But maté would be a great way
to stimulate GLP-1 release.
And then, of course, for those
of you that are interested
in more robust
activation of GLP-1,
then perhaps you might want
to consider some of the new
prescription GLP-1 analogues
that are out there.
But that's a more severe
stimulus for GLP-1, of course.
And for everybody, regardless
of whether or not you're trying
to lose weight, gain
weight, or maintain weight,
I think we're going to be
hearing a lot more about GLP-1
analogues and drinks and
supplements and things of that
sort that stimulate GLP-1 in
the very near future because it
does appear to be a very
important biological mechanism.
Before we begin, I'd
like to emphasize
that this podcast is separate
from my teaching and research
roles at Stanford.
It is, however, part
of my desire and effort
to bring zero cost to
consumer information
about science and
science-related tools
to the general public.
In keeping with
that theme, I'd like
to thank the sponsors
of today's podcast.
Our first sponsor is Levels.
Levels is a program
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The blood glucose or blood
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Let's talk about caffeine.
So as I mentioned
earlier, caffeine
is consumed by basically most
all adults every single day
and consumed at very
regular times each day.
In fact, if you were to take
a look at your caffeine intake
or the caffeine intake
of somebody close
to you, what you
would realize is
that they don't do so well if
their caffeine intake arrives
even 10, 20, or 30 minutes past
their expected or usual intake
of caffeine.
That's pretty
remarkable, and it brings
to mind ideas that
we are all, quote
unquote, "addicted to caffeine"
or that caffeine is somehow
bad.
I'm certainly not going to make
the argument that caffeine is
bad.
First of all, I'm a
regular caffeine user.
I wouldn't call myself
a caffeine abuser,
but I am a regular
caffeine user.
And caffeine is known to
have certain health benefits.
I listed off a few
of them earlier,
but I'll mention those again
now before going forward.
Caffeine is known to have
certain neuroprotective
effects.
And that is because
of its ability
to increase neuromodulators,
such as dopamine,
but also other
so-called catecholamines
like norepinephrine.
If you don't know
what those names mean,
these are molecules that
increase levels of alertness,
motivation, and drive.
And so then therefore not
surprisingly the large scale
analyses of the relationship
between depression and caffeine
shows that, provided people are
not drinking so much caffeine,
that it makes them
overly anxious,
that regular intake of
caffeine is inversely related
to levels of depression.
So it may have some
antidepressant effects.
And those could be
direct or indirect.
What do I mean by that?
Well, you can imagine that if
people are ingesting caffeine
and they are more motivated
to do work and pursue
quality social
interactions, then
the probability that they will
have depression could be lower.
It could also be that
there are direct effects
on the chemical systems
of the brain that
relate to mood and well-being
that could offset depression.
It is not clear whether
or not the effects
of caffeine in
countering depression
are direct or indirect.
Nonetheless, there's
a relationship there,
and it's an interesting
and positive one.
Or I should say
negative correlation,
positive effect overall on mood
and well-being, to be exact.
Now it's also the
case that caffeine
can improve mental performance
and physical performance.
This has been demonstrated in
tens of thousands of studies.
I will review a few studies
on this, in particular, today.
But to just give
you a sense of how
caffeine works at the level
of its timing and impact
on mental performance and
physical performance, when
we ingest caffeine,
provided that we don't have
a lot of food in our stomach
and that our blood sugar isn't
particularly high, generally,
we experience an increase
in alertness within
about five minutes.
And that increase in
focus and alertness peaks
around 30 minutes after
ingestion of caffeine
and persists for as
long as 60 minutes.
Now this is assuming that one
takes caffeine in pill form
or drinks the entire
caffeine drink
within a short period of time.
But a little bit
later, I'll talk
about how you can consume
caffeine at regular intervals
while doing mental work or
physical work in a way that
can further increase
mental performance
and physical performance.
But let's just touch
on what caffeine
intake really does
for mental performance
and physical performance.
Perhaps the most robust
finding across all
of the studies
that I've examined
is that caffeine reduces
our reaction time.
That is, it improves
our reaction time.
It doesn't make it longer.
It makes it shorter.
So for instance, in
a laboratory study
where people were asked to hit
a lever every time they hear
a tone, you can greatly reduce
the time between the tone
and the pressing of the lever
if people ingest caffeine
about 30 minutes before
they do that task.
Now that seems like
a trivial task,
but this is also seen in the
domain of sports performance
and even in cognitive
performance, where
people have to arrive
at a particular answer
to a question.
And the answer to
that question has
to be pulled from
their memory banks
within their brain,
their hippocampus,
for instance, a brain
structure involved in memory.
And if you are asking
people, for instance,
to remember the capitals of
different states or cities
or to remember certain
historical facts,
they will do that at
a particular rate.
But if they've ingested
caffeine within the hour prior,
their ability to
recall that information
is much, much better.
They are faster, and
it does not appear
that accuracy is reduced.
In fact, in many cases,
accuracy is enhanced.
And that's because caffeine
both works on the reaction time
systems of the brain and body.
I'll talk about the mechanisms
for that in a little bit.
But it also stimulates
certain neurotransmitters
and so-called neuromodulators
within the brain and body
that give the neural
circuits in the brain that
are associated with
learning and memory a lower
threshold to activation.
What does that mean?
That means that we are
better able to access
the brain circuitry involved
in learning and memory
when we have a certain amount
of caffeine circulating
in our system.
So this makes
caffeine an incredible
performance-enhancing compound.
And I could give you
tens of thousands
of examples of this in humans.
But before I do that,
I want to just touch
on what we know about the
existence of caffeine in nature
and what the existence
of caffeine in nature
and its effects on other
animals tells us about what
caffeine does in humans.
Because as I alluded to
earlier, what caffeine is doing
for us is not just
making us more alert,
improving our memory, improving
our reaction time, and so on.
It's actually acting as
a powerful reinforcer
of experience.
And it's acting as not
just a powerful reinforcer
of the caffeine-containing
drink that we drink
but also the mug that
it's contained in,
plus the person that
we might be sitting
across from when we consume
that caffeine, and so on and so
forth.
If it's a little
bit hard for you
to conceptualize
what a reinforcer is
and why I'm calling
it a reinforcer,
let me spell it out in
three specific ways.
We often hear about
the word reward,
and we think, OK, if
we do certain things
and we like the outcome,
then those certain things
are rewarded.
Right?
If we're doing something,
we receive praise.
The praise is the reward.
And therefore, we
are more likely to do
that thing in the future.
In fact, a lot of
parenting is like that.
And a lot of life is like that.
However, when we
hear the word reward,
we often think about something
that feels good to us.
And certainly, if we've worked
hard and we get some praise,
that's natural for the
praise to feel good to us.
Or for instance, if
we work very hard
and we get a certain outcome--
a trophy, a financial outcome,
a degree outcome, recognition,
et cetera-- all of those
can act as rewards,
but those are all
conscious rewards.
We are aware that
they are happening.
Reinforcers are a little bit
different because the word
reinforcement can apply to
conscious rewards of the sort
that I just described,
but there are also
many ways in which
caffeine stimulates
the release of chemicals in our
body that act as reinforcers.
But those reinforcers
are subconscious.
That is, we are
not aware that they
cause this preference
for the activities that
cause their release.
So the study I'm about
to describe beautifully,
I believe,
encapsulates how is it
that humans came
to consume caffeine
and why caffeine exists in
nature and the powerful effects
of caffeine as a reinforcing
agent both in animals, insects,
and in you and me.
And the title of the
paper is "Caffeine
and floral nectar enhances a
pollinator's memory of reward."
Keep in mind that caffeine
is made from plants.
Some of you will say, duh,
but I think some of us
don't realize that the reason
why there is caffeine in coffee
is because coffee
comes from a plant.
It's a coffee
bean, certain teas,
which, of course, are
plants that people brew.
Caffeine is contained in those
teas, such as yerba maté.
Well, why would this
bitter substance-- because,
in fact, caffeine is quite
bitter in high concentrations.
Why would this bitter
substance be something
that insects or animals
would want to consume at all?
It turns out that,
in most plants,
caffeine is present in
small enough quantities
that insects and other animals--
and in fact, we can't actually
taste the caffeine.
If I were to give you a
little bit of pure caffeine,
yes, it would be a
stimulant for you,
but you would say
that it tasted awful.
It's in a category of compounds
that would strongly stimulate
the bitter receptors
on your tongue
and would make you
cringe and pucker
and essentially walk away from
whatever it is that contain
that caffeine and from
the experience that
contain that caffeine.
Well, in nature, caffeine
is present in very low
concentrations or is
masked by other flavors
within flowers,
beans, and plants.
And what this paper
really points to
is that caffeine
in nature is acting
as a reinforcer for bees that
are consuming different nectar.
So the way that it works
is that bees, of course,
go from flower to flower, and
they are consuming the nectar.
They are bringing nectar
and pollen back to the hive,
and that provides critical
nourishment for the bee colony.
The bees are foraging in a
way that includes information
about color, in particular,
ultraviolet color, things
that we can't see
but they can see,
because they have different
photoreceptors than we do.
And what the study shows is
that plants and nectars that
contain very small
amounts of caffeine
are the preferred
sources of food for bees.
And the study is
beautiful because they
were able to confirm that they
could mask the caffeine taste.
So they know that the
bees are not preferring
the taste of caffeine.
But what they do is
they pair caffeine
with different food
sources for the bees,
then they remove the caffeine.
And what they find is that
the bees very strongly
prefer flavors that
contain caffeine,
not because they could taste the
caffeine but rather for the way
that those caffeine-containing
flavors made the bees feel.
So how do those
caffeine-containing flavors
make the bees feel?
The same way that
they make you and I
feel, a little bit
more alert and thereby
able to do more work.
For the bee, the more
work is the consumption
of more food, which then has
a further reinforcing effect.
So what we're really
talking about here
is the fact that A, caffeine
exists in nature, in plants.
It exists in concentrations that
are very low, so low, in fact,
that they are not detectable to
the taste receptors of insects,
and, in many cases, to the
taste receptors of humans.
And, of course, there
can be high levels
of caffeine in a plant.
But if the plant also
contains compounds
that mask the
flavor of caffeine,
well then, those plants
are going to essentially
be even stronger reinforcers
for the flavor of the plant, OK?
So now we're talking
about strong flavors
plus strong neurostimulant
effects of caffeine.
And the most
important point here
is that all of these effects
of caffeine are subconscious.
It is not because the bee or
you likes the taste of caffeine.
In fact, most people, when they
take their first sip of coffee,
they find it taste bitter
and kind of noxious.
They don't like it.
You may not even remember that
because it happened so long ago
and because caffeine is
such a strong reinforcer
that very quickly you come
to like the taste of coffee.
You might even come to like
the feeling of your mug
in your hand.
You might even come to
like the smell of coffee
and so on and so forth.
And that's because
caffeine stimulates
the release of certain
neurochemicals in the brain,
in particular, dopamine
and acetylcholine,
two neuromodulators
that increase our focus
and alertness and our
feelings of well-being.
A little bit later,
I'll tell you
that caffeine stimulates
the release of dopamine
in a way that's
very much distinct
from the classical
dopamine pathway associated
with addiction and reward.
In fact, we can
think of caffeine
as having a somewhat privileged
access to the reward systems.
I'll give you a bit of a
hint of where this is going.
Caffeine stimulates the release
of dopamine and acetylcholine
not within the classic so-called
mesolimbic reward pathway.
That's just fancy nerd
speak for the reward
pathways of the brain.
They're associated with
things like sex and food
and drugs of abuse, like
cocaine and methamphetamine.
But rather, caffeine
seems to stimulate
the release of dopamine in
the parts of the brain that
are associated with
alertness and cognition,
meaning the forebrain.
This is very important.
We have multiple dopamine
systems in the brain and body,
and caffeine seems to
stimulate dopamine directly
within the components of the
brain that are associated
with clarity of
thought and well-being,
but more so clarity of thought.
Now, I'm also talking
about caffeine
as a strong reinforcer in that
it makes you feel good overall.
And it does.
And that suggests that it
also taps into the more
classic reward pathway.
But it does that in a very
interesting and frankly almost
diabolical way.
When we regularly
ingest caffeine,
it stimulates the increase
in dopamine receptors
at multiple sites throughout
the brain but, in particular,
within the reward
pathways of the brain.
So not the areas
of the brain that
are associated with focus
and clarity of thought
and cognition.
It does that, but it
is also increasing
the level of dopamine receptors
in the reward pathway.
And what that means is that,
for any dopamine that's
released in response to
a positive experience,
social experience, or any
number of the other things
that can stimulate
dopamine release,
there are more receptors,
more parking spots,
if you will, for that
dopamine to arrive at
and to exert its increases in
mood, increases in motivation,
and overall feelings of
drive and excitement.
So there are four ways
that caffeine works
that we need to understand.
First of all, caffeine acts
as a reinforcing agent.
It increases the
probability that you
will return to and engage
in a certain activity
or consume a certain
beverage or food.
Second of all,
caffeine increases
dopamine and
acetylcholine, which
are both neuromodulators
in the forebrain, which
helps us improve our ability to
think, to modify our rule sets.
That is, to adjust
our strategies
for different social
situations and mental demands
and physical demands.
And third, it increases
the number and efficacy
of dopamine receptors in the
reward pathways of the brain.
That is, it makes things
that would feel pretty good
feel even better.
And fourth, caffeine
acts as an antagonist
to adenosine, which offsets
the sleepiness that we would
otherwise feel from the
accumulation of adenosine that
occurs as we are awake
for more and more hours
throughout the day.
So let's talk first
about caffeine
as a reinforcing agent.
Again, this was first most
beautifully demonstrated
in this study on honeybees
where the bees prefer
nectars that contain caffeine.
And that all makes
perfect sense in terms
of the ecology of bees and
flowers that contain nectar.
There's an advantage, at
least in terms of adaptation,
that the flower benefits because
of distribution of things
from the flower, which is good
for the flowers and the bees
benefit, because
they're getting food.
And so there's a kind
of a symbiosis there.
But with humans, we're consuming
caffeine-containing beverages
for our sake.
I don't think we
have it in mind,
nor do the bees have
it in mind, frankly,
that we're trying to
preserve the plants that
provide the caffeine.
I think we would all suffer,
or I should say 90% of adults
would suffer greatly if all
the caffeine-containing coffee
and tea plants were
gone, certainly.
But most of us are not
consuming coffees and teas
and caffeine-containing
foods because we're
thinking about the
plants they come from
and we want to
help those plants.
We're thinking about how
we want to help ourselves.
And yet the point of the
reinforcing effects of caffeine
are that they are
largely subconscious.
We are not aware of them.
Now you might say,
no, that's not true.
When I drink caffeine, it
makes me feel really good.
So I'm aware that it
makes me feel good.
In order to illustrate how
reinforcement really works,
let me give you the
counter example, which
would be an aversive agent.
So we have reinforcing agents
and we have aversive agents.
Let's say that there were
compounds in nature that exist
in plants that are aversive.
And indeed, they are.
And let's say that
these compounds
were present at such
low concentrations
that you couldn't taste them.
Let's say you wake
up in the morning
and you go to your
refrigerator and you open it up
and you are thirsty,
and so you reach
for a nice rich red-containing
beverage in a glass jar.
Maybe it looks like
cranberry juice or something
of that sort.
Or even a nice clear
glass of water.
It looks like a jug of
water or a glass of water,
and you drink that.
Taste fine to you.
Maybe even tastes great to you.
And then let's say
about 30 minutes later,
you feel a little queasy,
you feel a little off,
you feel like going
back to sleep,
you just don't feel very good.
You don't know why,
but your nervous system
is a predictive machine, and it
has a process in which it back
integrates.
Or I should say
integrates backwards
into your immediate experience
that preceded that not so
good feeling.
We can reliably say that there
is a much lower probability
that the next day
when you wake up
that you would reach
for that same beverage
or for that same container even.
And maybe if you're in
a novel environment,
maybe you're staying in an
Airbnb or a hotel or something
of that sort, you might even
find that you don't really
like the kitchen in which
you consume that beverage
in the first place.
And you don't know why.
And unless you got very,
very sick the day before,
it's unlikely that you would
have such a strong response
that you would entirely avoid,
for instance, water or glass
jars containing
liquids, et cetera.
Let's say you went back
to the refrigerator
and you consume a beverage
again and you just
didn't feel so well,
you felt less good
than you normally would.
Well, even without
any ability to taste
what's in that beverage and
even without any understanding
of what was happening to
you at a conscious level,
there is a very,
very high probability
that you will avoid drinking
that particular beverage
and certainly at that location
and in the same volume
in the subsequent days.
That's just the way that
aversive agents work.
And they work by way
of activating neurons
in the gut that communicate with
areas in the brain that give us
this feeling of queasiness.
And for some of
you hearing this,
that pathway and
that association
with times in which you felt
queasy and as if you wanted
to vomit is so powerful that
you might even be feeling
some of that symptomology now.
For certain people that's going
to be increased salivation
which precedes vomiting,
we know that there's
a class of neurons
in the brain relate
to an area called area postrema
that actually stimulates
vomiting.
And if I keep
talking about this,
I'll probably feel
like I want to vomit,
so I'm going to move on
from this in a moment.
So when we ingest
caffeine-containing beverages
and foods, it's the
exact opposite scenario
as to what I just described.
Caffeine, as a
reinforcer, makes us
feel slightly better
or a lot better
in the immediate minutes and
hours after we ingest it.
So it's acting as
a reinforcing agent
not just while you are under
the effects of caffeine
but for the things that preceded
the ingestion of caffeine,
which is why you
return again and again
to caffeine-containing
beverages, such as coffee
and tea or maybe even foods
that contain caffeine,
even if the taste of those
foods is not something
that you would otherwise
consider, especially delicious.
In fact, most people when they
take their first sip of coffee
or tea or other
caffeine-containing beverage,
they find it to be very bitter.
And that's not because
of the taste of caffeine.
It's because of the taste of
the beverage itself independent
of caffeine.
However, when caffeine
is present in there,
they come to prefer that
taste over most all tastes.
In fact, they will, as
I mentioned earlier,
will invest a lot of financial
resources and time and energy
to make sure that they
get that beverage.
What they're trying to make sure
is not that they get that taste
but that they get the caffeine.
It is that positively
reinforcing.
And the taste therefore takes on
new significance, new meaning,
and we come to associate
it as positive.
And in fact, most of
us, including myself,
love the taste of espresso,
love the taste of coffee,
love the taste of yerba maté
even if the initial taste,
the very first time that
we consume that beverage,
was either neutral or negative.
And that is all because of
the reinforcing properties
of caffeine.
And then, of course, there
are the more direct actions
of caffeine.
That is, the faster
actions of caffeine.
And just to list those off
again very briefly so that you
have them in mind going
forward, caffeine also
increases the release of
dopamine and acetylcholine,
both of which are
neuromodulators
in the forebrain, which
increases clarity of thought
and your ability to rule
switch, your ability
to move from one
context to another
and change and understand
the rules of engagement,
social engagement, physical
engagement, mental engagement,
and so forth.
And as I mentioned
before, caffeine also
increases the number of
dopamine receptors in the reward
pathway, such that any good
thing that happens to you.
Any positive experience
that you have
will have a more potent effect
on your feelings of well-being.
And last but certainly
not least, caffeine
acts as an adenosine antagonist.
It reduces your feelings
of lethargy and fatigue
and your desire to
sleep by parking
in the receptors for
adenosine and not
allowing adenosine to have
its pro-sleepy, if you will,
effects on your brain and body.
I'd like to take a quick
break and acknowledge
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The reason I started taking
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Our gut is very important.
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I'd like to just briefly
talk about adenosine and some
of its molecular features.
And again, if you don't have
a background in biology,
don't worry.
I promise to make this
very clear to everyone.
First of all, caffeine is
what's called a methylxantine.
It's a plant alkaloid.
That's why caffeine
itself is very bitter.
Again, if I were to give
you just the tiniest
little bit of pure
caffeine, you would find
it to be extremely aversive.
So these plants that have
snuck small enough amounts
of caffeine into
them or that have
masked the flavor of
caffeine with other flavors
such that bees and humans
want to consume them,
while we don't know what
plants think, it does
seem very diabolical
and very clever
in that we are seeking out these
caffeine-containing plants,
beverages, and foods even
though caffeine itself
is this alkaloid that
is very, very bitter.
Methylxantine--
that is caffeine--
binds to adenosine receptors.
And there are really two
types of adenosine receptors.
There are these so-called A1
receptors and the A2 receptors.
And they are present in
different parts of the brain
and body at different levels.
We don't have to get too
far into receptor subtypes.
More importantly
to understand is
that adenosine makes us feel
tired because of the way
that it taps into
the ATP pathway.
The ATP pathway is central to
energy production and feelings
of overall energy in
our brain and body
in all cells and organ systems.
When caffeine binds to
adenosine receptors,
it prevents adenosine
from breaking down
certain components of the
energy production pathway.
And the net consequence of
that is increased cyclic AMP.
So basically, when
we ingest caffeine,
we are biasing
our system towards
the pro-energetic aspects
of these cellular pathways.
Now it's really important to
understand that, in biology,
even if you block a
receptor or you prevent
the activity of an enzyme and--
at least, in this
case, you end up
with more cyclic
AMP, more energy.
You're not really
getting more energy.
You're actually borrowing
energy against an overall system
that is frankly nonnegotiable.
What do I mean by that?
Well, let's say that you were
to wake up after six or eight
hours of sleep and to
drink a lot of caffeine
and keep drinking caffeine
throughout the day blocking
those adenosine receptors.
Yes, you'll offset fatigue.
You'll offset sleepiness
because that adenosine simply
can't function.
But at the point where the
caffeine becomes dislodged
from the adenosine
receptors, you
will have a massive glut,
a backlog of adenosine,
and you will feel
extra, extra sleepy.
So really, there's no
way to create more energy
in your system.
Really, what you're
doing is you're
changing the timing in which
the sleepy signals and the more
energetic signals are arriving.
And this is really important
to understand as the backdrop
to the various tools
that we're going
to get into next, in which you
can use caffeine for enhancing
mental performance and
physical performance
and other aspects of health.
But it's very important
to understand this concept
that, when you wake up in the
morning provided that you slept
well and enough
the night before,
your levels of adenosine
will be about as
low as they will ever be.
Actually, in order to get
your adenosine levels really
bottomed out, you want to avoid
caffeine in the first 90 to 120
minutes after waking.
We'll talk about why that
is because it turns out
there's a way to
completely clear adenosine
out of your system in the
hour or so after waking.
But for most people,
adenosine levels
are going to be
close to their lowest
after a good night's sleep.
But there's really no
negotiating the accumulation
of adenosine that's
going to occur
and going to bias you towards
feeling more sleepy than you
would.
Otherwise, that's going to
occur throughout the day.
There's really no way
to eliminate adenosine.
All you can really do
is block its function.
So it's sort of like borrowing
energy against the fatigue
that you will inevitably feel.
Now this actually
has a very important
socioeconomical relevance.
Before caffeine was regularly
consumed by human beings,
we were really slaves
to the light/dark cycle.
And this was especially
true before the presence
of artificial lighting.
But even before the advent
of artificial lighting,
humans were largely constrained
to the outside light/dark
cycle.
We need to be active during the
day and working during the day,
and we need to be
asleep at night.
Caffeine allows us
to divorce ourselves
from that circadian cycle.
Circadian just
means about 24 hour.
Caffeine allows us to do
that at least somewhat by way
of increasing our alertness.
That is, spiking our
alertness at various times
throughout the day
and even at night.
This is how we can have
shift workers, for instance,
that can sleep during
the day and then drink
a strong cup of
coffee at 8:00 PM
and then work into the night.
That ability completely
transformed our society.
Now, of course, the
healthiest schedule-- and we
know this with certainty.
The healthiest schedule
for brain and body
is going to be alert during the
daytime and asleep at night.
There's no question about that.
Shift workers run into all
sorts of health problems.
And thank you shift workers
for doing the important work
that you do.
We need you.
Air traffic controllers,
paramedics, firefighters,
police officers, et cetera.
But we know that there are
serious health consequences,
negative health consequences,
that is, for shift workers.
But for most people out
there, about 95% of people
follow a typical schedule.
They're awake during the
day and asleep at night.
And yet it used to
be before the advent
of caffeine-containing
beverages that, if you were
sleepy in the
afternoon, you either
had to take a nap or
battle that sleepiness,
that your activity rhythms
and your sleep rhythms were
governed by these circadian
changes in availability
of sunlight and when you slept.
And you just didn't
have the ability
to ingest a beverage
that would increase
your levels of alertness
because you block adenosine.
So this is important
to understand
that, nowadays,
we certainly live
in a time in which we use--
in fact, 90% or more of
adults and half or more
of adolescents and
teenagers use caffeine
as a way to negotiate
with, to borrow
against this natural pattern
of adenosine making us sleepy.
But again, you're
just offsetting
the effects of sleepiness
that adenosine causes.
You can't eliminate
the adenosine entirely.
The important point
is that adenosine
as a pro-sleep molecule
is a nonnegotiable aspect
of your biology.
In fact, it's so nonnegotiable
that, every 24 hours, you
are going to release
adenosine, and you're
going to release adenosine in
direct proportion to how long
you've been awake.
So the longer you've
been awake, the more
adenosine circulating
in your system.
There are really only a handful
of ways to completely clear out
adenosine.
The major one
being to get sleep.
The other is to take a short
nap, which, of course, is
sleep, but it's shallow sleep.
Or non-sleep deep
rest, so-called NSDR,
has been shown to reduce
levels of adenosine.
And there are certain things
such as viewing morning
sunlight, which because of
its effects on cortisol,
can quote unquote,
"clear out adenosine."
We'll talk about this in
more detail in a few minutes.
And there's also evidence that
certain forms of exercise,
provided that it's
brief and intense,
can also reduce adenosine,
not just block its effects.
Now that we've talked about some
of the incredible mechanisms
by which caffeine changes
our experience of life,
increases alertness
and mood, et cetera,
I want to talk about the
use of caffeine as a tool.
Now caffeine is a very
potent and useful tool
for enhancing mental
health, physical health,
and performance.
But there are certain
considerations
one has to keep in mind,
in particular, dose.
Now, first off,
not everybody will
respond to the same dose
of caffeine the same way,
but we can reliably say
that your body weight is
a good measure by
which you can estimate
what a healthy, useful
dose of caffeine would be.
So for most people,
ingesting 1 to 3 milligrams
of caffeine per
kilogram of body weight
is going to be the
range in which caffeine
can have positive effects
without making us feel overly
anxious and give us that
feeling that we're jumping out
of our skin and
turn the otherwise
positive experience of
caffeine into an aversive one.
For those of you that aren't
familiar with thinking in terms
of kilograms and
normally think in pounds,
I'll just quickly give you
some general estimations
that, for instance, 100
kilograms equals 220 pounds.
So for me, I weigh
100 kilograms.
That means that 1
to 3 milligrams--
again, milligrams,
thousandth of a gram.
1 to 3 milligrams of caffeine
per kilogram of body weight
would mean for me.
I could safely ingest 100 to
300 milligrams of caffeine
in a single dose,
in a single drink,
if that's the way
I'm consuming it,
or pill form if that's the
way that I'm consuming it.
And it's very likely that
that will be a tolerable dose.
However, if you are
not somebody that's
accustomed to drinking
caffeine on a regular basis,
I suggest you start on the
lower end of that 1 to 3
milligrams per kilogram
of body weight range.
So for instance,
if you're somebody
who weighs 50 kilograms, that's
approximately 110 pounds.
And you would be
pretty comfortable
ingesting somewhere between 50
and 150 milligrams of caffeine.
So what I recommend is that
people who are considering
using caffeine as a tool or who
are already ingesting caffeine,
start to think about
the dosage of caffeine
that you are ingesting
or plan to ingest
and the timing in which
you ingest that caffeine
relative to certain tasks
throughout your day,
your waking, and your sleep.
And we'll talk about
that in just a moment.
But the first step for
you is to figure out
how much you weigh
in kilograms and then
to go to that number of 1
to 3 milligrams of caffeine
per kilogram of body weight.
And that's a good
range in which you
might want to explore
the use of caffeine
in a single application,
meaning a single dose.
Now, I do realize that
some people out there are
drinking coffee all day long
or having coffee in the morning
and again in the afternoon.
What I'm referring to here
is the ingestion of caffeine
in a single bout, right?
1 cup of coffee or 2 cups
of coffee, for instance,
to achieve that 100
to 300 milligram
range if that's what's
appropriate for your body
weight.
But to avoid any confusion,
when I talk about dosage
of caffeine, what I'm
really talking about
is not the total amount of
caffeine ingested per day.
I'm talking about
the total amount
of caffeine ingested in one
sitting or setting, that is.
And if you're somebody who's
drinking caffeine multiple
times throughout the day, you
can imagine-- for instance,
let's say the
appropriate dose for you
in order to get an enhancement
in mental performance
or physical performance
is 200 milligrams.
And you are somebody who's
doing some work in the morning,
and you want to have
that lift in the morning
to be able to focus better.
And you're doing some physical
exercise in the afternoon
or vice versa that you
would ingest 200 milligrams
of caffeine at two
separate times per day
separated by about four hours.
Now you don't have
to separate them.
You could put them two
hours apart, for instance.
But we'll talk about half-life
of caffeine and so forth.
Just keep in mind that, if
you're ingesting 200 milligrams
of caffeine and that's the
appropriate dose for you
based on your body
weight and then you
are ingesting another 200
milligrams of caffeine an hour
later, you are effectively
ingesting approximately 400
milligrams of caffeine,
which is going
to start exceeding the dose
in which you can normally
tolerate without feeling
anxious and jittery.
With all of that
said, there is a range
of tolerance for caffeine
that's based on two things.
One is a preexisting disposition
that is whether or not
your genetics and nervous system
and the backdrop of your life,
how much stress
you're experiencing
tends to make you feel more
anxious and alert and jittery
before you ingest any caffeine.
And the other is how so-called
caffeine-adapted you are.
We often hear about tolerance.
Tolerance means
something very specific.
It's the ability to ingest
more and more of something
with a plateau that is a no
increase or an actual reduction
in the effectiveness
of that thing.
But here we're not really
talking about tolerance
to caffeine.
What we're talking about
is being caffeine-adapted.
A simple way to
understand whether or not
your caffeine-adapted or not
is that, if you drink caffeine
and it tends to
increase your heart rate
and make you feel more alert
and a bit more anxious,
then chances are you are
not caffeine-adapted,
provided the amount of caffeine
is within the healthy range
for you, that is, the ranges
we talked about a moment ago.
However, here's somebody
who drinks caffeine
and you actually feel
alert and relaxed,
chances are you are
caffeine-adapted.
And so at various times
during today's episode,
I'll talk about people
who are caffeine-adapted
and people who are
not caffeine-adapted.
We'll talk about the use of
caffeine every other day.
I know a few habitual caffeine
drinkers including myself,
just the simple mention of
that probably sounds aversive.
But there is actually
great utility
to using caffeine every other
day as opposed to every day.
But just keep in
mind that some people
will drink caffeine and not get
much of a lift from it at all.
Other people will
drink caffeine,
and they will feel extremely
anxious even at dosages
far lower than that 1 to
3 milligrams per kilogram
of body weight range that
I described a moment ago.
So you have to take into
account individual differences.
That said, 1 to 3 milligrams of
caffeine per kilogram of body
weight for a given sitting.
For your morning coffee or
your morning yerba maté tea is
a good range from
which to start.
And I do encourage you
to go online and look up
the various beverages and
foods that you might be
eating that contain caffeine.
For instance, some people
are surprised to discover
that the coffee that they get
from some of the more standard
popular vendors out
there, the small coffee
or the medium
coffee, for instance,
can contain as much as 400 to
600 milligrams of caffeine.
And the large
coffee that is often
sold at those
commercial vendors can
contain as much as 1 gram,
1,000 milligrams, of caffeine.
Now you may be
adapted to that such
that it doesn't make
you feel anxious,
but if you wonder why
you feel irritable
and you get a headache
when you don't
get that caffeine or
that amount of caffeine
at precisely the time that
you're used to getting it
each day, that's because
you are consuming
quite large quantities of
caffeine on a regular basis.
So I do recommend whether or not
you drink soda or coffee or tea
that you figure out
the source of that.
OK, so figure out what
vendor you purchase it
from, what kind of coffee,
and go online and spend
a little bit of time
because the information is
out there to discover
what levels of caffeine
you're actually ingesting.
Now if you happen to be
ingesting more than 1
to 3 milligrams per kilogram
of body weight of caffeine,
that's not necessarily bad.
However, you do want to
be careful about ingesting
very high levels of caffeine
over long periods of time
in your life because there can
be issues that start to arise.
In particular, a bias
towards higher levels
of anxiety and depletion
of certain electrolytes.
Because caffeine
is a diuretic can
cause you to lose sodium and
other things of that sort.
And also just from simply
a dependent standpoint,
it does appear that if you
ingest high levels of caffeine
that is exceeding the
dosages that normally you
could get away with
and get just as
much mental-enhancing and
physical-enhancing benefits
that you can cause
some disruption
to the microvasculature.
You can bias yourself towards
headaches, anxiety attacks,
and you can become
actually quite irritable
when you're not getting those
higher levels of caffeine.
So I do encourage
you to figure out
not just what an appropriate
caffeine dosage would
be for you but also
how much caffeine
you might already be ingesting.
The first tool I'd
like to talk about
is one that I've
mentioned before
on this podcast several times.
And it's something that
if you haven't heard of
will be very useful to you.
And if you have heard
this tool before,
I'm going to add some
additional features
to the description
of this tool that
should make this
worthwhile for you as well.
And that is to delay
your caffeine intake
to 90 to 120 minutes after
waking up on most days.
And I'll be very
clear as to days
in which you might want
to ingest caffeine more
closely to when you wake up.
Why would you want to delay
your caffeine intake to 90
to 120 minutes after waking?
The answer to that
is very simple.
Many people wake
up in the morning.
They drink caffeine within
10, 20, 30, sometimes
within 2 minutes of waking.
And they feel more
alert naturally.
That makes sense because
of the effects of caffeine
in blocking the
effects of adenosine
that I talked about
earlier and its effects
on other
neurotransmitter systems.
But then what they find is
that, in the early afternoon,
in particular, after lunch,
they experience a dramatic dip
in their overall levels of
energy, the so-called afternoon
crash.
And in most cases, the
way they respond to that
is to ingest more
caffeine, which
indeed can increase their
levels of mood and alertness.
However, as we'll
soon talk about,
there is a problem
with ingesting caffeine
in the afternoon if it
falls within 8 or 10
or dare I even say 12
hours of going to sleep.
And that is, the caffeine
ingested in the afternoon--
for most everybody, let's say
for 95-plus percent of people--
disrupts the
architecture and quality
of their nighttime sleep.
And I should say that
it doesn't necessarily
impact their ability to fall
asleep and maybe even sleep
through the night but that the
depth and quality of that sleep
is disrupted by consuming
caffeine in the afternoon.
A little bit later,
I'll talk about how
you can offset some of
those negative effects
if you absolutely require
caffeine in the afternoon.
But there's a huge advantage
to restricting your caffeine
intake to the early
part of your day
but not consuming caffeine
within the first 90
to 120 minutes after waking.
In fact, many people find that
if they delay their caffeine
intake to 90 to 120
minutes after waking up
that they feel more
alert in the morning,
and they completely avoid
that afternoon crash.
Now that said, many
people, including myself,
do need a short nap
or non-sleep deep rest
or other form of relaxation
for 10 to 30 minutes
in the afternoon.
That is natural and healthy.
I'm not referring
to the need for that
when I refer to the
so-called afternoon crash.
What I'm talking about
in the afternoon crash
is a inability to recover
energy and focus and a need
to consume more caffeine just to
make it through the afternoon.
By delaying caffeine intake to
90 to 120 minutes after waking,
there are a couple of things
that are accomplished.
First of all, you offset
that afternoon crash.
And this is an effect that
many people experience
the very first time they
start delaying their caffeine
intake to 90 to 120
minutes after waking.
And the reason this works
so well is the following.
As I mentioned
earlier, adenosine
is a molecule that builds up
the longer that we are awake.
It is a molecule that
is reduced or cleared
from our system by sleep.
So when we emerge
from sleep regardless
of how long we've slept,
our adenosine levels
are lower than they
were when we went
to sleep the previous night.
If you slept well
enough and long enough,
those adenosine levels
can be very, very low,
but they are never
completely zero.
When you wake up in
the morning, even
if you're one of these people
that springs out of bed
and is ready to attack the
day-- and here I'm certainly
not describing myself.
I'm not one of those people.
I tend to wake fairly slowly.
But if you're one of those
spring up and attack the day
or you're one of
the people who moves
more slowly into your
day, regardless, there's
still some residual
adenosine in your system.
And this is
particularly the case
if you did not get enough
sleep or enough depth of sleep
the night before.
The correct ratio is a slow-wave
sleep and rapid eye movement
sleep.
And for those of you
interested in optimizing sleep,
I'll just refer you to our
master your sleep episode
of the Huberman Lab podcast,
the perfect your sleep episode
of the Huberman Lab podcast.
And we have a tool kit for sleep
all of which are available,
zero cost, time-stamped, et
cetera at hubermanlab.com.
You wake up in the morning.
And your adenosine levels are
low, but they're not zero.
And if you didn't sleep that
well or deeply enough the night
before, you're going to have
more adenosine in your system.
You might think
the logical thing
to do is therefore
to drink caffeine
and to block the
adenosine that's there.
But what happens
if you do that is
there's an accumulation, a
sort of glut of adenosine
that hangs around.
And then in the afternoon, when
the effects of that caffeine
start to wear off,
you will experience
the so-called afternoon crash.
As I mentioned
earlier, there is a way
to clear out the adenosine
that's present when you wake up
in the morning and to
clear it out essentially
completely without just
blocking its receptors
and letting it accumulate
or hang around.
And the way to do that
is to deliberately spike
your cortisol.
Now, many of you have heard of
cortisol, the so-called stress
hormone, as a bad thing.
And indeed, chronically elevated
cortisol is a bad thing.
It depletes your immune system.
It's bad for
psychosocial effects.
It tends to make us feel
anxious and on and on.
But cortisol itself is not bad.
Cortisol is wonderful.
Cortisol enhances the
efficiency of the immune system.
It makes us alert and focused.
It stimulates our metabolism.
It does a huge number of
positive things, provided
that it is released in
a circadian fashion.
That is, at the
appropriate times
every 24 hours and that it tends
to peak very close to waking.
In fact, one of the reasons
you wake up in the morning,
assuming that you weren't
woken up by some noise
or sleeping in an environment
that's too warm, et cetera,
is that your cortisol
levels start to rise.
And shortly after waking,
your cortisol levels
will start to reach their peak.
And when I refer to
a cortisol pulse,
that's just biology
nerd speak for a rise
and peak in cortisol.
You want that cortisol pulse
to occur early in the day close
to waking, and you want that
for a couple of reasons.
First of all, if you don't
restrict that cortisol pulse
to early in the
day, it will tend
to bleed into the
later parts of the day.
And actually, a late
shifted cortisol peak
is one of the
hallmark signatures
of depression,
low-level depression,
and serious depression.
And it can start
to disrupt sleep
and certainly can
disrupt mood metabolism
and your immune system.
So you want that cortisol
peak early in the day.
How do you ensure
that that happens?
Well, you wake up
in the morning.
And whether or not you're
a bounce-out-of-bed type
or you're more groggy, you kind
of wade slowly into the day
type like I am, you wake up,
and you don't ingest caffeine.
Fine and, in fact,
beneficial to hydrate
with water and electrolytes.
Terrific.
In fact, I would
say necessary to get
bright light in your eyes
ideally from sunlight.
I've talked about
this many, many times
before on the podcast.
If you wake up before
the sun comes out,
then turn on bright
artificial lights.
But then certainly once the sun
is out and even on cloudy days,
in fact, especially on cloudy
days, get outside for anywhere
from 5 to 20, maybe
even 30 minutes.
Do some work outside, take
your breakfast outside
if you're a breakfast eater.
Get something done outside even
if it's just to get outside
and get bright
light in your eyes.
Why?
Well, because it's
been shown in studies
on humans that getting
bright light in your eyes
in the first hour after
waking or as soon as possible
after waking increases the
peak of that cortisol pulse
by 50%, 5-0.
And that cortisol pulse, yes,
increases mood, yes, increases
alertness, but it does one
other very important thing,
which is that, through
an indirect pathway,
it can clear out any
residual adenosine that
might be present in your
system when you wake up
in the morning.
Again, this is going to be
especially important for those
of you that are not
getting as much sleep
or as much quality
sleep as you would like.
It's going to be very important
for you to get that morning
bright light ideally
from sunlight,
get that cortisol peak going.
Other ways to increase
that cortisol peak
would be to do some
physical activity.
If you don't have time to do
a full workout, well then,
getting some movement--
10 minutes of
skipping rope or even
5 minutes of skipping rope
or jumping jacks or walking
if that's all you have time
for ideally while getting
the sunlight in your eyes.
But that's going to zero
out the adenosine present
in your system.
If, however, you were to
wake up and immediately
drink caffeine--
caffeine itself can
stimulate the release
of cortisol a little bit
more than it would otherwise
be present in your system.
But by blocking those
adenosine receptors
and because of the
indirect effects
of caffeine on the
cortisol system,
you actually are reducing
the clearance of adenosine
that would otherwise occur.
So I realize that's a mouthful.
Just to be very
clear, if you wake up
and you ingest
caffeine right away,
you're blocking the
adenosine receptor,
but you're not clearing it out.
You're also preventing cortisol
from having its normal increase
and rise such that it can
directly clear out adenosine
because cortisol can
clear out adenosine.
And that's what you want.
You want to be at
maximum alertness
and focus in your morning
and throughout your day.
And by delaying your caffeine to
90 to 120 minutes after waking,
you set up your system so that
you get that morning cortisol
peak.
Ideally, a peak that's
even greater because you're
getting your bright
light viewing.
And then when you ingest your
caffeine 90 to 120 minutes
after waking, not only will
you be craving it just a little
bit, but you will be
drinking that caffeine
on an already existing backdrop
of increased alertness for two
reasons.
One is adenosine is zeroed
out, and your cortisol peak
is higher.
And so now when you
ingest caffeine,
you can actually ingest
levels of caffeine
that are a little
more reasonable that
almost with certainty are
going to fall in this 1 to 3
milligrams per kilogram dosage
and will allow you to feel
really alert and will
carry that alertness well
into the afternoon hours without
the need to drink more caffeine
and thereby will prevent
you from drinking
caffeine and disrupting
your nighttime sleep.
And, of course, by getting
better nighttime sleep,
you're going to zero out
your adenosine even more.
So what I'm describing here
are essentially two tools.
I'm telling you to get
morning sunlight and maybe
some exercise in
conjunction with that
even if it's brief exercise.
But the main tool
of delaying caffeine
90 to 120 minutes after
waking has immediate effects,
but it also sets in
motion a cascade or domino
falls that lead to better
sleep and more wakefulness
the next night and the next
day and so on and so forth.
Now I realize there are some
people who just simply cannot
or will not delay their caffeine
90 to 120 minutes after waking
for whatever reason.
First off, let me say
that, if you are somebody
who likes to wake up and
do very intense exercise
within the first 90
minutes after waking, well,
in that case, it would
be appropriate to ingest
your caffeine just prior
to doing that exercise.
Not a problem.
Not a problem.
But you should expect that
the combination of drinking
caffeine very shortly after
waking plus exercising very
intensely shortly after
waking will increase
the intensity of that early
afternoon and afternoon fatigue
that you feel.
Now for some people,
that's a great thing.
They can afford to take a nap
or do non-sleep deep rest, step
away from work, and so forth.
In that case, I
strongly encourage
you to do whatever
it is that allows
you to get regular exercise
because regular exercise is
going to be very beneficial.
In fact, we did
an entire episode
called tool kit for fitness that
describes a couple of different
but really one
main structure that
allows you to get the
appropriate amount
of resistance training and
cardiovascular training
and flexibility training
throughout the week.
I happen to follow that
program, and it works very well.
And it does involve
some of those workouts
to come very early in the
morning shortly after waking.
And in those cases,
I do ingest caffeine
just prior to those, so within
10, 20 minutes of waking.
However, on other
days, I personally
delay my caffeine intake
90 to 120 minutes,
and I've done that
to great benefit.
And most people, if not,
all people that try that,
have reported the same.
I should mention that some
people will find getting out
to that 90 minutes
to be excruciatingly
difficult because they're
so accustomed to ingesting
caffeine close to waking up.
In that case, maybe just
push out your caffeine intake
by about 15 minutes
each day until you
hit that 90 to 120-minute mark.
And that will make
it much easier.
It might take you a
week or so to get there.
But once you get
there, you'll find it
to be quite easy to maintain.
The other thing is that,
if you are somebody
who insists on drinking caffeine
very shortly after waking,
I would encourage you to drink
half of your caffeine then
and then the other half of your
caffeine about an hour later.
That also will help offset
some of the afternoon crash
for reasons related to the
so-called kinetics of caffeine.
Caffeine has a quarter
life of about 12 hours.
That means that if you were
to ingest a cup of coffee
at let's say 8:00 AM--
and let's say 100
milligram coffee
just for sake of simplicity,
that about 25% of that caffeine
action--
we wouldn't really say 25
milligrams, but about 25%
of that caffeine
action will still
be present at 8:00
PM that night,
which is pretty remarkable.
So there's a long arc
of caffeine effects,
and this is why it
can impede sleep if we
take caffeine in the afternoon.
But again, if you're
somebody who wakes up
and you really need
caffeine right away
and you refuse to do this
90 to 120-minute delay thing
that I'm talking about,
well then, in that case,
I would drink half of
your caffeine upon waking
and then a little bit more or
the other half about an hour
later.
And that will extend the
arc of that caffeine effects
such that you don't need
it again in the afternoon
because you won't experience
the afternoon crash.
Because of the way
caffeine works,
I should mention that,
if you ingest caffeine
on an empty stomach, it will
have a more potent stimulant
effect.
That will also tend to increase
the level of jitteriness
that caffeine can produce.
Later, I'll talk about ways
to offset that jitteriness,
but I'll just tell
you one tool now.
Many people opt to take
100 milligrams of theanine,
T-H-E-A-N-I-N-E, theanine, as
a way to offset some of that
jitteriness.
Theanine will reduce
the jitteriness
of caffeine, which is
why many energy drink
manufacturers and even
some coffee manufacturers
are now putting theanine
in energy drinks
and in ground coffee
because, no surprise,
it allows people to consume
more of that beverage
and thereby purchase more
of that beverage, which
is what these vendors want
without feeling overly
anxious and jittery.
So you can take
pill form theanine
if you want with your caffeine.
I don't tend to do that.
Rather, I control the total
dosage of my caffeine.
I do tend to consume
caffeine on an empty stomach
because I do restrict
my caffeine intake
to the early part of the day.
And I generally eat my first
meal somewhere around 11:00 AM,
and then I generally my last
meal some time around 8:00
PM or so.
Those are averages.
I would say plus
or minus an hour.
And that's not because
I'm religiously
following any kind of
time-restricted feeding.
It's just that
tends to work best
with my schedule
and my appetite.
But again, that's
a general theme.
There are days in which I
wake up and I'm very hungry,
and I might ingest something,
small snack or something.
Or if I'm meeting
somebody for breakfast,
sometimes I'll have breakfast.
Sometimes I won't.
And so on and so forth.
The point is that
you can get away
with drinking less caffeine to
get the stimulant effect if you
do it on an empty stomach.
And if you're somebody
who likes to exercise
on an empty stomach--
and I'm one of those people--
well then, ingesting caffeine
just prior to exercise
can be a fantastic tool.
A little bit later,
we'll talk about some
of the physical
performance-enhancing effects
of caffeine.
But I'll just briefly
jump to a point about that
as we relate to
morning exercise.
If you are somebody who
regularly ingests caffeine--
and we can define
regularly by, if you've
ingested caffeine every
day for the last two weeks,
you're a regular
consumer of caffeine.
Whereas if you're somebody
who only ingests caffeine
somewhere between two and four
times per week, well then,
you are not a regular
consumer of caffeine.
You're an intermittent
user of caffeine.
Well, if you're somebody who's
a regular user of caffeine,
the performance-enhancing
effects of caffeine are going
to be most dramatic if you
take two or three days off from
drinking caffeine,
which to my mind as a--
I don't want to call
myself a caffeine addict
but a regular caffeine user.
That's a horrible notion to
me, it is an aversive notion,
because I do like the
effects of caffeine so much.
But if you really want
to see the maximum
performance-enhancing
effects of caffeine,
you will do either
one of two things.
You will either
abstain from caffeine
for a few days or three days
prior to ingesting caffeine,
or you will use caffeine
on an empty stomach.
It's very clear that
caffeine on an empty stomach
enhances both the mental
and physical enhancing
effects of caffeine.
And, of course, all of
that has to be stated
on the backdrop of consideration
that you're very, very hungry,
it can be make it
hard to concentrate
and so on and so forth.
So I'm not encouraging people to
starve themselves by any means.
Certainly, don't do that.
But if you want to maximize the
performance-enhancing effects
of caffeine, you will consume
it on an empty stomach.
And then as a final point to
that, caffeine is a diuretic.
It causes us to lose fluid
and, along with that fluid,
to excrete sodium because
of the effects of caffeine
on various processes
within the kidney.
So one thing that works
very well to maintain mood
and alertness longer given
a certain amount of caffeine
intake and to avoid
the jitteriness
and what can sometimes feel
like a crash or low blood sugar
feeling or even blurry
vision is to make sure
that you consume at least
an equal volume of water
with your caffeine.
And ideally, that
water would contain
maybe a small pinch
of salt or some sort
of electrolyte drink--
or powder, rather.
For me, I use element.
Full disclosure, they are a
podcast affiliate and sponsor.
But you don't need to do that.
You could simply just have
a glass of water alongside
your coffee or espresso or your
yerba maté and just put a small
pinch of sea salt in that or
evem just playing table salt.
And that will help offset some
of the jitteriness of caffeine.
A lot of people think that,
when they ingest caffeine,
they get the jitteriness and
crash because their blood
sugar is low.
And while that can be the
case, oftentimes, it's
simply because of the
excretion of sodium
that's occurred when
they've ingested caffeine.
So I encourage you
to hydrate well
and to hydrate with
something that contains
a little bit of sodium.
Obviously, not so much
that increases hypertension
or something of that sort
but a small amount of sodium
or an electrolyte
drink like Element.
And there are other
electrolyte drinks
out there that can accomplish
the same, of course.
Just a couple of
quick notes about
theanine because there are
a growing number of products
out there that contain theanine.
And there's certainly a growing
number of people out there
who are using theanine for the
effect that I described before,
which is to offset some of
the jitteriness associated
with caffeine-containing
beverages or foods.
And, of course, I
should mention that I've
talked about the
effects of theanine
on sleep at that sleep
tool kit that you
can find as a free download.
You don't even have
to sign up for.
Anything you just download
it from hubermanlab.com.
Go to the menu, go
to a newsletter.
You'll see the
tool kit for sleep.
You'll see that the
so-called sleep stack
that I use and recommend
includes magnesium 3 and 8,
something called
apigenin and theanine,
although that sleep
stack is designed
to be taken 30 to 60
minutes prior to sleep.
And I make the point
there, and I'll
make it again here that
ingesting theanine prior
to sleep is not a good
idea if you are somebody
who tends to have very vivid
dreams, night terrors, or night
walk--
sleepwalking, excuse
me, et cetera.
In that case, eliminate theanine
from the sleep stack.. .
However, a number of
people are using theanine,
and products are using
theanine to offset jitteriness
from caffeine-containing
products
during the daytime, daytime
consumption, that is.
A couple of notes about
theanine-- theanine
is something that is
present in green tea, right?
It's now been created
as a supplement.
It's what's called a
nonprotein amino acid.
So while there are amino
acids and proteins,
there are, of course, amino
acids and nonproteins.
And theanine is one such
nonprotein amino acid.
Theanine tends to stimulate
the so-called glutamate and
glutamine pathway.
It's actually very similar
to glutamate and glutamine,
and it has a lot of effects
on a lot of different aspects
of the nervous system.
But the general
effect of theanine
is to compete for the receptors
for certain neurotransmitters.
And the neurotransmitters
I'm referring to
are all excitatory
neurotransmitters,
things like glutamate.
And they govern a tremendous
amount of our daily thinking
and action and
feeling, et cetera,
because they're present
at so many connections
between neurons in the brain.
Theanine competes for the
receptors for glutamate
and tends to reduce our
overall levels of alertness.
So really, when people
take theanine along
with caffeine,
what they're doing
is they're really
taking a slight--
I don't want to call it
depressant to the point
where it misleads people and
makes people think that it
will make you depressed.
The word is a little
bit misleading.
But it tends to
reduce or blunt some
of the more excitatory
pro-alertness actions
of neurons in the brain.
So when you take it
alongside caffeine,
tends to, quote unquote,
"even things out a bit."
I should mention that
the dosages of theanine
that are effective
for offsetting
the jitteriness of caffeine
is 200 to 400 milligrams,
and the studies that
I was able to find
showed that essentially up
to 900 milligrams per day
can be safe.
But that's a very high
dosage of theanine.
In fact, so much so
that it might increase
sleepiness to the point
where it wouldn't feel good.
There are also some
positive effects
of daytime consumption
of theanine
that are independent of reducing
the jitteriness of caffeine.
For instance, there's
a study demonstrating
that 17 days of ingesting
theanine at these 200 to 400
milligram dosage at one
to three times per day
can reduce depression
and anxiety.
There are also some good
data out there showing
that theanine can have positive
effects on endothelial cells--
so blood vessels,
capillaries, and so on--
and increase some of the
function of blood vessels,
allowing them to pass
more blood through them
and give them a little bit
more elasticity, if you will.
So theanine has certain
pro-sleep effects
if it's taken prior to sleep.
It can enhance the quality,
depth, and duration of sleep.
Again, if you're a
sleepwalker or somebody who
has extremely vivid dreams
from which you wake up
in the middle of the
night, probably best
to leave out theanine or
maybe reduce the dosage down
to 100 milligrams.
And if that's still too much,
then eliminate it completely.
But theanine can be terrific
for enhancing quality, depth,
and duration of sleep.
It can also reduce
the jitteriness
associated with
caffeine-containing beverages
and foods.
And it has certain
antidepressant
and pro-endothelial effects.
That is, it can
offset depression.
It can offset anxiety, although
those are minor effects,
subtle effects.
And it has been shown to
improve endothelial cell.
That is, vessel and capillary
function and structure
in ways that can be beneficial
for both brain and body.
Now one final point
about theanine
that's worth paying
attention to is
that the kinetics
of theanine are
such that you don't need to take
theanine every time you ingest
a caffeinated beverage.
When we ingest caffeine,
the peak effects of caffeine
occur about 30 minutes
after we drink it.
And there, I'm assuming
one takes it all at once.
And this is a key point that
we'll come back to later rather
than sipping your coffee
slowly over a couple of hours
or an hour.
If you drink all 200 or
300 milligrams of caffeine
in your coffee or 600
milligrams of your coffee
if you're getting one of
those commercial coffees
and you take theanine
along with it,
theanine will block
some of the jitteriness
and anxiety-inducing
effects of caffeine
that can occur for much
longer than the effects that
caffeine lasts.
So the peak in theanine occurs
about an hour after ingestion.
I suppose if you want
to get really fancy
and really dial in
the kinetics, you
could ingest theanine
about half hour
before you ingest your caffeine.
But I think that's getting a
little bit excessive in terms
of controlling your
microenvironment, if you will.
I think it would be perfectly
fine to take a 100 to 200
milligram capsule of theanine
along with your coffee or tea
or so forth and just realize
that if you drink more caffeine
or you extend your caffeine
intake over several hours
that you don't necessarily
have to take theanine repeated
times throughout the day.
I'd like to take a
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Let's talk for a moment
about when to avoid caffeine.
And in the same stroke,
let's also talk about some
of the myths around caffeine.
For instance, one of the
major myths around caffeine
is that it can
increase osteoporosis.
It turns out that, while there
is a relationship, of course,
between calcium
and osteoporosis--
that is reductions
in bone density.
And it is the case that
caffeine can extract calcium
from certain tissues.
The large scale studies that
are out there essentially
prove that, if people are
ingesting enough calcium
through their diet, which
most everybody is-- although
certainly, there
are some people that
need to supplement calcium
or make it a point to consume
more calcium-containing foods.
But assuming that
you are getting
adequate levels
of calcium, there
is no direct relationship
between caffeine intake
and osteoporosis, at least
not that I'm aware of.
I know this was debated
for a number of years
in the literature,
but the literature
seems to have arrived
at a general consensus
now that caffeine itself is not
going to create or exacerbate
osteoporosis, provided people
are getting enough calcium
through their diet.
That is, through foods, through
supplementation, or both.
Some of the other
myths around caffeine
are that, for instance, caffeine
will reduce testosterone levels
or will reduce estrogen levels.
Other myths out there
are in exact opposite
to that, that caffeine will
increase testosterone levels,
in particular, free
testosterone levels.
There have been some large scale
studies addressing the hormone
effects of caffeine.
They are a little
bit difficult to do.
I should just
mention that caveat.
And the reason they
are difficult to do
is because 90% of adults
are consuming caffeine.
And therefore, you
can imagine it's
very hard to find a control
group to compare the caffeine
consumers to.
In particular, a
control group that's
well controlled for other things
like lifestyle, diet, exercise,
et cetera.
However, when one controls
as well as one can
for all the various factors that
could impact hormones, what one
discovers is that caffeine
intake, at least at the dosages
we talked about earlier, 1
two 3 milligrams per kilogram
of body weight or even
up to double that,
that there are no consistent
increases or reductions
in testosterone or
estrogen in men or women
that can be directly attributed
to the caffeine intake.
And I say directly attributed
because in these association
studies, one always
has to wonder,
for instance, if because people
are ingesting more caffeine,
they have more energy and
therefore exercising more.
And exercise is
known to have effects
on testosterone, estrogen,
and other hormones,
whether or not the effects
of caffeine on those hormones
is indirect and so
on and so forth.
And this all just
underscores the challenges
of doing studies on
humans in the wild
in their natural habitat
of living as opposed
to an acute study as it's
called to bring someone
into the laboratory
and studying them just
for those hours or moments.
With all that said, there does
appear to be a relationship
between caffeine intake and
so-called sex hormone binding
globulin, which is a protein
present in the body of both men
and women that binds to
the sex steroid hormones--
testosterone and estrogen--
and prevents them
from being in their
free or active form.
It has been shown that
ingestion of caffeine--
even in the sorts of dosage
ranges that are considered safe
and that we've been discussing--
can increase sex hormone
binding globulin such
that it can slightly
reduce overall levels
of free testosterone
and free estradiol in women.
Now those effects are relatively
minor, but they do exist.
If any of you are interested
in reading further
into the effects of
caffeine on hormones,
I'll just refer you to
a couple of studies.
We will link to this in
the show note caption.
The title of the
study is "Consumption
of caffeinated beverages and
serum concentrations of sex
steroid hormones in US men."
And within this study,
there is a reference
to a equally sized
empowered study done
on women, both of
which converged
on the same conclusion, by
examining more than a thousand.
So in this case, 1,410 men or
more than a thousand women,
that there are increases in
sex hormone binding globulin
associated with increased
intake of coffee, in particular.
But they were able to narrow
that down specifically
to ingestion of caffeine.
So it's not coffee per se that's
causing the increase in sex
hormone binding globulin.
It's actually caffeine itself.
So again, the increases in
sex hormone binding globulin
were not so significant
that, at least to my mind,
they seem like a
concern, although I
think that it is worth noting
that if you're going to consume
caffeine that you probably
want to consume caffeine
in a way that is in dosages and
with the sort of timing that
will allow you to get away
with ingesting caffeine
but not to excess, so to
derive the benefits of caffeine
without for instance driving
up sex hormone binding globulin
too far.
Now why would that
be a good idea?
Why would you want to make
sure that you have enough free
testosterone and free estrogen?
Well, some of that is
related to the acute effects
of those hormones in terms
of well-being and libido
and strength and mood, et
cetera, but some of those
also relates to the longer
term effects of sex steroid
hormones.
Many people don't
realize this, but the sex
steroid hormones
operate on the receptors
at the surface of cells
to have immediate effects.
But they also can enter
cells and actually
go into the nucleus of cells
where the DNA of those cells
are contained and control gene
expression in those cells.
So the sex steroid hormones,
testosterone and estrogen,
are controlling a lot of
different cellular functions
over long periods of time.
So blunting their action
over long periods of time
is probably not a great idea.
But again, at the
dosages of caffeine
that we're talking about
today, 1 to 3 milligrams
per kilogram of body
weight, unlikely
that the increases in sex
hormone binding globulin
that one experiences from that
are going to be detrimental.
And certainly, the
positive effects
of caffeine that one experiences
in terms of mental performance
and physical
performance and the fact
that it increases energy
to do the sorts of things
like exercise that we
know can profoundly
improve hormone
profiles, twofold
or threefold improvement
in hormone profiles.
In that case, it seems that
ingesting caffeine is overall
a good thing, provided
it's not in excess.
That also makes this
the appropriate time
to mention one of the more
impressive effects of caffeine,
which is on overall levels
of mood and mental health.
There are several
studies on this,
but the one that I'm
particularly fond of
was published in 2019
in Psychiatry Research.
And the title of the paper
is "Inverse association
between caffeine intake
and depressive symptoms
in US adults."
And these are data from the
National Health and Nutrition
Examination Survey.
And the basic takeaway is
that, while, of course,
there are a ton of
different factors
that are going to
relate to whether or not
people are depressed or
not, life circumstances,
genetics, and so on, that--
and here I'm quoting
from the study.
"Caffeine's psychostimulant
properties--
that just means
the ability to make
us feel more alert
and positive--
appeared to protect against
depressive symptoms."
And, of course, they acknowledge
that additional studies are
needed, but this is just one
of several studies pointing
to the fact that people who
regularly ingest caffeine
in the appropriate
dosages do seem
to enjoy an antidepressive
effect overall.
I wouldn't want anyone
to consider caffeine
a treatment for
severe depression
or at least not
alone a treatment
for severe depression.
But provided the
anxiety-inducing effects
of caffeine can be kept in
check through use of theanine
or making sure that the dosage
and the timing of caffeine
ingestion is correct,
then caffeine overall
seems to be good for our
mood and prevent depression
or at least keep
depression at bay
when depression might otherwise
surface or be more severe.
And, of course, there are the
don'ts surrounding caffeine
intake as it relates to sleep.
And to put it very
simply, sleep--
that is getting
enough quality sleep
each night-- is the foundation.
It is the bedrock of mental
health, physical health,
and performance.
Sleep and the power of sleep
far exceeds any nootropic
you could ever take,
any prescription drug
you could ever take, any
health-promoting tool
for your immune system,
your metabolism,
your mental function,
your physical function you
could ever take.
Sleep is the bedrock.
I know a lot of people
experience challenge
with sleep.
Nobody is perfect about sleep.
That's important
to keep in mind.
I think a good goal is
to get enough quality
sleep of sufficient duration
80% of the nights of your life
and then as much as possible
to make sure that the remaining
20% of nights you are
not getting enough
sleep for good reasons as
opposed to hard reasons.
Good reasons would
include raising children.
That's important.
After all, every species
desires to make more of itself
and to preserve and extend
the well-being of its young,
so child-rearing is a
perfectly legitimate reason
to get a lack of sleep.
But you really want to strive
to get quality sleep most nights
of your life, which means that,
even if you're somebody who
can, quote unquote,
"drink an espresso"
and then fall right asleep,
that you avoid caffeine intake
in the 12 hours prior to sleep.
I realize not everyone
will be able to do that.
And in fact, I
sometimes violate that,
so I tend to go to sleep
around 10:00 PM every night,
sometimes 11:00,
occasionally 12:00 midnight,
but usually around
10:00 PM every night.
I confess that my last
ingestion of caffeine
is not always 10:00
AM or prior to that,
so sometimes I will
have caffeine up
until 11:00 AM or maybe noon.
And very, very rarely, I'll have
an afternoon coffee or espresso
or noncalorie-containing
soda or tea or something
that's of that sort.
But I really tried to
restrict my caffeine intake
to the early part of my day
that is before noon, given
that I go to sleep around
10:00 PM each night.
And I strongly encourage
everyone out there
to try and limit their
afternoon caffeine intake.
This is something that Dr.
Matt Walker, who's an expert
sleep researcher out of
University of California
Berkeley Psychology and
neuroscience department there,
author of the incredible
book Why We sleep.
He's been on this podcast,
many other podcasts,
talking about the
importance of sleep.
He will remind us, and
I'll remind you now
that the quarter life
of caffeine is 12 hours.
I mentioned this earlier, but
I'm going to repeat it again.
And that means that, if you
ingest caffeine at noon,
25% of its effects
more or less, OK?
I'm using a broad stroke here
to talk about quarter life.
25% of that is still going
to be bioactive at midnight
that night, which will disrupt
the early phase of your night,
the amount of slow-wave
sleep, which then in turn
will disrupt the amount of rapid
eye movement sleep, which will
disrupt your
emotional processing
during the following day
and so on and so forth.
None of this is
to say that if you
have the occasional cup of
coffee in the afternoon,
that it's going to
completely demolish
your sleep/wake cycle forever.
But I really encourage people
to avoid drinking caffeine
in the 12 hours prior to sleep.
And if you can't do that, within
the 10 hours prior to sleep.
And if you can't do that, within
the 8 hours prior to sleep.
So really try and
limit your caffeine
intake in the 8
to 12 hours prior
to going to sleep at night.
And, of course, slow-wave
sleep, aka deep sleep,
is the sleep that's associated
with somewhat mundane dreams,
which makes it sound like it
might not be that important.
But it's also the sleep that's
associated with growth hormone
release, which is important
for protein synthesis,
repair of all bodily
tissues and metabolism.
And slow-wave sleep
is also critically
attached to your
immune system's ability
to clear out bacteria and
viruses that might otherwise
infect your tissues.
Now I'd like to talk about
caffeine and performance.
And that includes both
mental performance
and physical performance.
Now I'd like to
talk about caffeine
and its positive
effects on performance
when used correctly.
And here we are referring
to both mental performance
and physical performance.
The exploration of caffeine
as a pro-performance tool
has been explored since
the 1930s, at least
that's some of the earliest
documented literature on this.
Although I have
to imagine, given
that people have been
using caffeine for much
longer than that, that long
ago somebody realized that,
by ingesting a certain
plant, that they
felt much more
alertness and were
able to hunt and gather or do
any number of different things
better and, as a
consequence, decide
to consume more of that plant.
Now these days, we
consume a lot of caffeine
in the form of coffee
and tea mainly,
and some people consume it in
the form of caffeine tablets
or energy drinks, et cetera.
Across the board, one
finds that caffeine intake
at a level of 1 to 3 milligrams
per kilogram of body weight
improves reaction time.
That is, it reduces
the amount of time
to take a physical action or
to answer a question correctly
with a verbal response.
It can also improve
coordination.
It can also improve
memory, although I
do want to mention that, whereas
most studies of the effects
of caffeine on improving
mental and physical performance
involve taking caffeine at 1
to 3 milligrams per kilogram
of body weight before the
mental task or physical task,
there is also a pro-performance
effect of caffeine on memory
if one takes caffeine after
learning certain material
or I should say being
exposed to certain material.
We'll come back to
that in a few minutes.
If one examines reaction
time, mood, alertness, focus,
and memory or the
ability to call up
information from memory, or
physical dexterity, power
output, endurance, and
overall feelings of well-being
during exercise and
exertion, caffeine
has been shown in numerous
studies in both men and women
to improve all of those
metrics significantly.
So this is all just
to say that caffeine
is an incredible
performance-enhancing tool.
Now, what's not obvious from
the statement that caffeine is
a performance-enhancing
tool across the board
and in men and women and
in different contexts
is that the way in
which caffeine is taken
is very important.
Because 90% or more of
adults consume caffeine,
finding controls for studies of
caffeine is really challenging.
That is, finding people
who don't ingest caffeine
regularly is a very challenging
task for the researcher.
And as a consequence,
many of the studies
of caffeine on
human beings involve
depriving regular
caffeine users of caffeine
and then examining the
effects of caffeine
given after a period of, say,
5 to 15 days of abstinence
in a person that is essentially
experiencing mild withdrawal
symptoms because they haven't
had the caffeine that they were
used to getting.
So this is an important point.
And it's a point that
likely exacerbates
the observed pro-performance
effects of caffeine.
Now all of that isn't
necessarily a problem,
provided you keep it in mind.
And it actually points
to a way in which
even if you're a
regular caffeine user,
you can extract more of
the benefits of caffeine.
The simplest way to
do this, for instance,
is to look back to what we
talked about earlier in terms
of the need to have most of your
cortisol increase restricted
to the hour or hours just
after waking in terms of mood
and alertness and performance.
One of the ways to increase
the peak of that cortisol
early in the day is to
consume caffeine shortly
after that peak occurs.
And this was really
nicely demonstrated
in a study entitled
caffeine stimulation
of cortisol secretion across
the waking hours in relation
to caffeine intake levels.
We will provide a
link to this study.
It's a somewhat
complicated study
because they looked at a bunch
of different times of day
for caffeine intake.
And I should mention,
in this study,
they use this 300 milligrams per
day or 600 milligrams per day.
So that's quite high, although
for people of sufficient body
weight and who are accustomed
to taking caffeine,
it's certainly not
going to be in excess
of what a lot of people
out there are taking.
But basically, what they
observed was the following.
Cortisol responses to
caffeine are reduced but not
eliminated in people who consume
caffeine on a daily basis.
What this means is
that, if you wake up--
as I recommended
earlier, you avoid
drinking caffeine for the first
90 to 120 minutes after waking,
but you do get some sunlight or
other bright light in your eyes
in that time, maybe
even get some exercise
in that time, which
would be even better--
and then you ingest caffeine,
you will get a further increase
in cortisol, which,
provided it's restricted
to the early part of the day,
is a good thing overall for mood
and alertness.
So this is a simple
performance-enhancing tool,
which is to stack
caffeine on the tail
of that early cortisol peak.
I should also mention,
however, that, in this study,
they had people do a five-day
caffeine abstinence prior
to being tested with 300
milligrams or 600 milligrams
of caffeine.
So the simple tool to extract
from this and other studies
like it is that, if
you want to experience
the maximum alertness-promoting
effects of caffeine
when you ingest it
early in the day,
you would abstain from
caffeine for five days
and then ingest caffeine 90
to 120 minutes after waking.
I would still hope that you
were doing all the other things
that I described-- morning
sunlight, exercise, et cetera--
correctly.
But regardless, it's very clear
that a five-day abstinence
from caffeine however
painful that might be
will increase the
performance-enhancing effects
of caffeine when you take
caffeine on that sixth day.
Now, I'm sure many of you out
there are saying, why would
I ever want to abstain
from caffeine for five days
in order to just get this
six-day performance-enhancing
effect?
Well, there are a couple
of reasons for doing that.
Perhaps you're planning to
travel to a new time zone,
and you want to use
caffeine as a stimulant
to stay up during the
day in the new time zone.
That's a somewhat unusual case.
Others of you
might be interested
in the pro-physical performance
effects of caffeine.
We'll talk more about
these in a little bit.
But you want to get
the maximum strength
increase or the maximum
endurance increase
from ingesting, in this
case, 300 to 600 milligrams
of caffeine.
Well, in that case, abstaining
from caffeine for five days
will greatly exacerbate
the pro-performance effects
of caffeine when you take
it on that sixth day,
although admittedly,
those five days are
likely to be pretty painful if
you're a regular caffeine user.
Another variation
on this, however,
might be to have the
amount of caffeine
that you ingest on a daily
basis and then go back
to your regular level of
caffeine intake on that
day in which you need the
caffeine to really boost
your mood, energy,
and performance.
Another reason why you might
want to abstain from caffeine
or reduce your caffeine
intake for a period of time
and then go back to your
regular caffeine intake
is simply to identify how
much of an effect caffeine
is really having on your overall
level of daily functioning
and mood.
This was something
that was actually
covered in beautiful detail
in a book by Michael Pollan
all about caffeine.
It's available on Audible.
I really enjoyed that book.
It describes his experience
with the decision
to completely
abstain from caffeine
for a period of months, although
I confess that after hearing
that book, what it
basically made me want to do
is never quit drinking
caffeine because it sounded
as if, at least my
interpretation was, that
even after several weeks
or months of abstaining
from caffeine, that
he still fantasized
about the effects of caffeine.
But he did mention that, when
returning to ingesting caffeine
after a period of
long abstinence,
that it had almost a--
let's not call it a
psychedelic property,
but it had such
obvious effects on mood
and alertness and
feelings of well-being
that it really highlighted
for him the extent
to which caffeine normally was
allowing him to just function
what he thought was normally.
So in other words,
many of us don't even
really know what our
normal basal level
of cognitive and
physical functioning
is because we're
ingesting caffeine
on such a regular basis.
I confess that, as much
as I enjoyed that book
and as intriguing as his
description of caffeine
abstinence and then the
return to caffeine was,
I don't intend to ever
find out personally.
Now a very good
reason why you might
want to abstain from caffeine
for a deliberate period of time
and then return
to caffeine intake
is for its physical
performance-enhancing effects.
And here we can look to a
really interesting study.
The title of which
is "Time course
of tolerance to the performance
effects of caffeine."
And what I like about this
study is that, while yes,
it does say that
abstaining from caffeine
and then returning
to caffeine intake
can enhance physical performance
in a very specific way,
it also says that, if you
take caffeine regularly,
you can still see the physical
performance-enhancing effects
of caffeine.
Although they are not quite
as robust as they would be had
you abstained from caffeine.
The design of the study
is pretty straightforward.
They had people either
ingest 3 milligrams
per kilogram of caffeine
for 20 consecutive days.
Many people are already
doing that, I realize,
but they had people
do that or ensure
that they were doing that.
Or others ingested a
placebo for 20 days,
so they abstained from
caffeine without realizing it.
Then after that 20 days of
either ingesting caffeine
or a placebo, their
peak performance
was measured in terms
of aerobic output.
But prior to that measurement,
they had caffeine, OK?
So it's 20 days of caffeine
and then a 21st day of caffeine
and then the physical
task on that 21st day.
Or it's 20 days of
abstinence from caffeine.
And then on day 21,
you get caffeine,
and you get the
same physical test.
And what they discovered was
that the ingestion of caffeine
increased peak performance
in this aerobic output
dramatically if people had
abstained from caffeine.
But for people that had consumed
caffeine all the way through up
until that day, it still was
effective to ingest caffeine
on day 21 but not as effective
as it would have been had
they abstained.
And in fact, the
magnitude of what
they call ergogenic
effect, which
is the pro-performance-enhancing
effect of caffeine,
was higher on the first
day than in subsequent days
when they allowed people to
continue caffeine intake.
So the takeaway from this study
is really straightforward.
If you want to get the maximum
physical performance-enhancing
effects of caffeine, you abstain
from caffeine for 20 days.
Then on day 21,
when you're going
to do the physical
thing, the task,
you ingest caffeine about
30 minutes to an hour
before you do that
physical challenge.
Now 20 days of
abstinence is going
to be rough for a lot of people.
I certainly don't want to
sign up for this study.
In which case, you might want
to do five days of abstinence
as we talked about before.
And then on day six is the day
that you ingest caffeine and do
the physical task.
There are even some
studies showing
that you can abstain from
caffeine for just two days,
for just 48 hours.
And, in particular, if you are
a regular user of caffeine,
this allows you
to, on day three,
ingest caffeine at the dose
that's appropriate for you
and do the physical, or I should
mention mental performance task
and perform significantly
better than those
that have been taking caffeine
throughout the entire period
leading up to the challenge.
So you don't necessarily
need to abstain for 20 days
in order to get the
pro-performance effects
of caffeine on day 21.
You could do five days of
abstinence prior or even
two days of abstinence prior.
Or if that's intolerable
to you as it is in my mind,
to me, to just reduce your
caffeine intake slightly
or even perhaps have it
if you can tolerate that
in the week or two weeks
or maybe even three
weeks preceding some
physical or mental challenge.
Now again, this sort of
implies that you're going up
against a marathon,
or you're going up
against a series of long
tests, maybe standardized tests
in one day.
There, I just really
want to point out
that there is an abundant
literature showing that people
perform best on mental tests
if they are in the state
that they were when they
studied for that material.
Now in college, I knew
a number of people
who took this to the extreme,
thinking that if they were
to study under the
effects of alcohol,
that they would be best
off consuming alcohol
prior to taking exams.
And it turns out
to not be the case.
Here we're talking,
in particular, about
psychostimulant effects of
caffeine and other compounds.
So don't think
that you can drink
or be under the influence
of THC and then take--
when you study and then take an
exam under the same influence
and do just as well as you would
had you not ingested anything.
Please don't let
that be the takeaway.
However, do let
it be the takeaway
that caffeine's
effects are made more
potent by a brief to not so
brief period of abstinence
prior to taking a
dosage of caffeine.
And then the final
point to make is
that, if you are somebody who
is not accustomed to drinking
caffeine, meaning you're
hypersensitive to caffeine
or you don't regularly
ingest caffeine, please
do not ingest
caffeine on the day
of any important mental
or physical challenge
or performance, because
what you will find
is that because you are
not caffeine-adapted,
you will experience changes
in your thermal regulation,
in your levels of
anxiety and jitteriness,
and your levels of
focus that could
be very detrimental to mental
or physical performance.
So you don't want to throw
yourself in the deep end
by ingesting caffeine if
you're not used to it.
And I should mention
that for people
that are not accustomed
to ingesting caffeine
or are very sensitive
to caffeine.
Even 25 to 50 milligrams
of caffeine in the amount
that's found in, for
instance, a piece
of certain types of chocolate
can actually cause anxiety.
So be careful there.
Here, I'm referring only to
people that are accustomed
with caffeine intake.
So what I recommend is to
explore the ergogenic effects
of caffeine during your training
and then to make a decision
about what you can
reasonably and reliably do
in terms of abstinence and
then pulse with caffeine
on the day of the challenge.
I get a lot of questions
as to whether or not
caffeine has different
effects on the nervous system
and on performance in
particular, depending on phases
of the menstrual cycle.
So I explored that in my
research for this episode,
and I found two
studies both of which
we will reference in
the show note captions.
The first one is entitled
"Caffeine consumption
and menstrual function."
So it's actually the
relationship between caffeine
and menstrual function.
We will do an entire episode
about the menstrual cycle
and menstrual function.
But the other one as it
relates to performance
was published in 2020 in the
European Journal of Nutrition,
which is "Ergogenic
effects of caffeine
on peak aerobic cycling power
during the menstrual cycle."
And the basic takeaway
of this study is--
frankly, a very nice study,
showed that quote, "Caffeine
increased peak aerobic cycling
power in the early follicular,
preovulatory, and midluteal
phases of the menstrual cycle."
Thus, the ingestion--
and again, here they
use 3 milligrams of caffeine
per kilogram of body mass
might be considered an
ergogenic aid for women
who are in the menstrual
cycle during all three
phases of their cycle.
So keep that in mind, women--
for those of you that are
regular users of caffeine
or you're using caffeine to
enhance physical performance,
there does not seem to be any
menstrual cycle phase-dependent
effects of caffeine
on performance.
That is, caffeine seems
to always increase
physical performance
regardless of the phase
of the menstrual cycle
you might happen to be in.
I'd like to touch on a little
bit more of the use of caffeine
for enhancing
mental performance.
Yes, it is the case that
ingesting 1 to 3 milligrams
of caffeine per kilogram of
body weight in the 30 minutes
or so prior to
doing a memory task
or sitting down to
doing some studying
or learning of any kind,
physical or mental performance,
of any kind is beneficial
for all the reasons we talked
about before, relate to dopamine
and acetylcholine, et cetera.
But it turns out that
it is also the case that
spiking one's adrenaline
and other so-called
catecholamines-- so this would
be dopamine, norepinephrine,
and epinephrine-- after
a bout of learning
can greatly enhance
memory for the information
that one was trying to learn.
That's right.
Spiking your adrenaline
after learning
can greatly increase
memory for the material
you're trying to learn.
In fact, this is a practice that
dates back centuries and was
written about in a beautiful
Annual Review of Neuroscience
on the biology of memory by
James McGaugh, where he talks
about medieval
practices of children
being taught information and
then being thrown literally
into cold water to stimulate
the release of adrenaline
and that increase in adrenaline.
While the mechanism wasn't
completely understood,
it was understood that
that sort of shock
to the system from
the cold water
led to better memory and
retention of the information
that these children
had been exposed to.
And it turns out
the exact same thing
is true for adults
in the laboratory
or kids in the laboratory.
And here I'm not
suggesting throwing anyone
into cold water.
If you want to get
into cold water,
there's a reason we
call it deliberate
cold exposure on the
podcast is that it
should be deliberate and
controlled by you, not
by somebody else.
And if it's controlled
by somebody else,
that might be military
screening or something.
But here we're talking about
deliberately increasing
your levels of adrenaline and
other catecholamines, dopamine,
norepinephrine, et cetera.
You can do that certainly
by deliberate cold exposure
with a cold shower or
getting in up to your neck
in cold water of any kind.
But the other way to do that
is to spike your adrenaline
by ingesting 1 to 3 milligrams
per kilogram of caffeine
after sitting down to try and
learn some material I confess
that, more often than not, I
use caffeine in the same way
that most people
use it, which is OK.
I'm going to sit down.
I'm going to research
information for a podcast
or assemble some information
for a paper or grant,
and I want to focus.
So I will drink a cup of
coffee at the beginning of that
and maybe even throughout
that or a couple of yerba maté
at the beginning
or throughout that.
Or I'll sip on one or both
throughout trying to learn.
And that works
quite well in terms
of maintaining focus and
alertness and retention
of information, but
it is indeed the case.
That is, the research
supports the fact.
And I've experienced
the fact that,
if I abstain from caffeine while
I'm trying to learn something--
but then I drink caffeine
immediately after.
Somewhat surprisingly to me
but certainly in a way that's
consistent with the
research literature, memory
for the information that I was
focused on prior to ingesting
that caffeine is much greater.
And here I'm talking about
as a personal anecdote,
but this is actually what the
data point to both in animals
and in humans.
And if you think about
it, it makes perfect sense
because the way that the
memory systems of the brain
are organized is that we go
through life experiencing
things.
We encounter surprises
both good and bad.
We go through the motions of
things both typical, mundane,
exciting, and novel,
and not novel.
And then every once
in a while, something
will happen that will
spike our catecholamines.
Dopamine, typically if
it's a positive surprise.
Adrenaline, which
can be associated
with both positive
surprise or positive events
and negative events
or surprises.
And without fail, increases
in the catecholamines
tend to lock in
memories for things
that preceded the increase
in those catecholamines.
Again, the catecholamines
being dopamine, epinephrine,
and norepinephrine, sometimes
all three in combination,
sometimes just two of those,
sometimes just one of those,
depending on the experience.
So it makes perfect
sense that using caffeine
at the end of a
learning bout would
enhance our memory
for the information
that we are trying to learn.
So if you decide that you
want to try and extract
this performance-enhancing
effect of caffeine, what
I recommend would be to try and
abstain from caffeine for a day
or two prior.
But if you can't,
you just continue
with your normal
caffeine intake.
But then when you sit down
to study or learn something
to not ingest any caffeine as
you do that but then afterward
to ingest caffeine.
Now in theory, you could
probably further enhance
the memory encoding
effects of adrenaline
and the other catecholamines
by drinking caffeine
and then taking a cold shower or
doing deliberate cold exposure
if you really wanted to
or had the ability to
or doing some sort of
intense form of exercise.
And we'll talk in
a moment about how
caffeine, exercise, and the
adrenaline system interact.
But as a brief but
relevant to side,
brief bouts of intense exercise
ranging from 10 to 50 minutes
or so have been shown to
improve memory for information
that one was trying to learn
prior to the intense exercise.
This is work from Dr.
Wendy Suzuki's lab at NYU
as well as other
laboratories, some of the work
that's being done at Stanford
in the Mind, Body Laboratories.
And our laboratory points in
the direction of these kinds
of effects as well.
They all come back to the
same general neurochemical
theme, which is that,
when we experience
an increase in these
catecholamines that include
adrenaline, dopamine,
and norepinephrine,
the memory systems of the
brain flip on in a way that
try to capture the information
and the perceptions
and the experiences that we
were exposed to just prior
to the increase in
catecholamines and caffeine
but also exercise
and also cold water.
And, of course, any of those
alone or in combination
all increase the levels
of catecholamines,
so it makes perfect
logical mechanistic sense
as to why this would work.
And in fact, it does work.
If you want to remember
specific information,
you might consider using
caffeine as you move through
and absorb and are exposed
to that information.
But you might also
consider using caffeine
after being exposed
to that information
because studies in
animals and humans
show that that is a potent way
to increase memory for what
you are just exposed to.
I should mention that
what I just described also
pushes back on something that
I know a number of people
perhaps have heard about
and maybe even use, which is
this notion of the nappuccino.
I remember hearing about
this a few years back.
It was sort of
trend, if you will.
The trend involved
drinking a cup of coffee
or a double espresso and then
going down for a nap typically
in the afternoon
and then waking up.
And the idea was that the
caffeine would hit your system
right at the time that
you awake from the nap
and that you would be better
able to focus and exercise.
There are a couple of things
about that practice that I
don't like.
First of all, it
implies, in most cases,
that you're napping
and ingesting
caffeine in the afternoon, which
I realize for many students
and for people that are
comfortable staying up
until the wee hours of the
night and then waking up
late the next day might be
compatible with their schedule.
But again, because of the
sleep-diminishing effects
of caffeine--
and we talked about earlier.
I'm not crazy about
the idea of people
ingesting caffeine
in the late afternoon
in order to perform better
in the late afternoon.
Far better would be to
restrict caffeine intake
to the early part of the day
as we talked about earlier.
The other reason
is that the data
on things like
non-sleep deep rest
and naps in the afternoon--
and again, the rule here
is that you don't have to nap.
But if you want
to nap, it's been
shown that naps of
90 minutes or less
or non-sleep deep rest
protocols-- and you
can find those-- for instance,
there's one with me speaking.
You just put NSDR
Huberman into YouTube.
You can hear that.
It's completely zero cost.
There are other NSDR
scripts out there
now, of course, if you prefer
those, that those can all
lead to increases in one
of the catecholamines
at least, which is dopamine.
That's been shown in a really
nice neurotransmitter labeling
study, not from my laboratory,
but from another laboratory,
but also can improve mood,
focus, and alertness on its own
without the need to
ingest caffeine prior
to going into those states.
And in fact, ingesting
caffeine prior to a nap
or ingesting caffeine
prior to NSDR
is most certainly going to
reduce the effectiveness
of that nap and
NSDR in restoring
natural levels of
alertness and focus
that would lead to the
performance-enhancing effect.
So I'm not such a fan of
the so-called nappuccino,
although if any of you
out there have derived
great benefit from
it, definitely
let me know your protocol
and what you've experienced.
Put it in the comment
section if you would.
I'd appreciate that.
There's another very important
and potent use of caffeine
for enhancing performance.
And this relates not just to
the dopamine and epinephrine
and the arousal-inducing
effects of caffeine.
And it doesn't even just relate
to the effect of caffeine
on enhancing frontal
lobe function.
It does include all
that, but it also
includes those reinforcing
effects of caffeine
that we talked about at the
beginning of the episode.
And the best way to illustrate
these performance-enhancing
effects of caffeine
that stem directly
from its association
with reinforcement
is to highlight a study.
And the title of the study
is "Blood dopamine level
enhanced by caffeine in men
after treadmill running."
And as the title suggests,
this was carried out in men,
but there's no reason to think
that the same results wouldn't
also be present in women.
There are some sex-dependent
effects of caffeine.
I'll touch on just
briefly at the end.
But those are largely
present in kids.
That is, adolescents and
teens as opposed to adults.
So this study is
really interesting.
What they had people do was
run on a treadmill and either
ingest caffeine-- again, 3
milligrams per kilogram of body
weight--
or to not ingest caffeine.
And then they looked
at levels of dopamine
and other neurotransmitters
and hormones,
such as prolactin and cortisol.
And the basic takeaway
is, as the title suggests,
that exercise, while on its
own, can increase cortisol
in healthy ways, provided it's
not too intense and too long.
A little note here, if you
have trouble recovering
from exercise or
you want to continue
to derive the benefits from
exercise, in general, best not
to do high-intensity exercise
for longer than 75 minutes.
Or 90 minutes probably
being the outer threshold.
I realized that there are
some genetic freaks out there
or people that are
chemically assisted
that can recover from very
intense long bouts of exercise.
But most people don't do
well through long bouts
of intense exercise
on a regular basis.
And limiting their
intense exercise
to 60 minutes or less--
that doesn't include
the warm-up--
is going to be beneficial.
See the episode on
tool kit for fitness
if you'd like details on that.
Exercise is known to increase
levels of dopamine, cortisol,
and other catecholamines and
neurotransmitters very potently
and things like
testosterone and estrogen
in ways that we know
are beneficial to us
and, of course, have all
these positive effects
on the musculoskeletal system
and cardiovascular effects.
But unbeknownst to most
people, ingesting 3 milligrams
per kilogram of caffeine
prior to exercise further
increases the dopamine release
associated with exercise
specifically.
And this has two
important effects.
First of all, that
increase in dopamine
is great because it provides
a long-lasting increase
in focus alertness
and motivation,
not just during the exercise,
but also after the exercise.
And second, it-- that
is, caffeine and dopamine
in combination--
act as a reinforcer
to make the experience of
exercise and the period
immediate after exercise
more pleasant and, in fact,
reinforcing.
So in other words, one
way to enjoy exercise more
and to enjoy the activities
that follow exercise more
and to experience a genuine
increase in dopamine that's
beneficial for
mood and alertness
is to ingest caffeine
prior to exercise.
Now this is important because
a number of people out there
are exercising, love
exercise, love eating great,
love doing all the
things that are
beneficial for their health,
but a number of people out there
really don't like to exercise.
And that serves as a serious
block for their willingness
and their consistency
to exercise.
Ingesting caffeine gives
us energy to exercise.
It increases the release of
neurochemicals and hormones
that are good for
us during exercise.
But as I'm highlighting
here, it also
increases the
reinforcement pathways
associated with exercise.
That is, it creates
a positive feeling
about the general theme
of engaging in exercise,
and it creates a general
positive experience
of the things that
follow exercise.
So I think this, if nothing
else is a call for or support
for the idea, that
ingesting caffeine
as a performance-enhancing
tool makes perfect sense.
But for those out there
that don't enjoy exercise,
in particular, certain
forms of exercise,
ingesting caffeine can
change your relationship
to that exercise.
In other words, make it more
positive, much in the same way
that ingesting caffeine
alongside a certain taste that
would otherwise be neutral
or maybe even negative
can actually make the taste of
that particular drink or food
positive.
So again, this brings us back
to the reinforcing properties
of caffeine that
are subconscious.
It's not just about the
enhanced performance in the test
or the enhanced performance
on the treadmill
or with the weights in the gym.
It's enhanced feelings
of mood and well-being
that are genuine because
of the effect of caffeine
on certain neurotransmitter
and hormone systems,
but it also is creating
an overall milieu
of reinforcing all
of the things that
led in to occur during
and occur after exercise.
I do want to point out something
that's very important as it
relates to combining
things like caffeine
and exercise in order
to increase dopamine.
This is something that
came up in the episode
that I did on dopamine,
motivation, and drive, which
turns out to be one of
our most popular episodes.
Again, you can find that at
hubermanlab.com and links
to all formats with
time stamps, et cetera.
This also came up in
the episode on ADHD
because of the relationship
between ADHD and dopamine.
And that's this notion
of dopamine stacking.
In the episode on dopamine,
motivation, and drive,
I pointed out that, while there
are a near-infinite number
of things that can
increase dopamine release,
most notably positive surprise
or positive anticipation
or experiencing a win.
Certainly, there are compounds,
both drugs of abuse, food, sex,
and certain supplements
that can increase dopamine
to varying levels and
to varying degrees,
both healthy and unhealthy.
That's all contained in
that episode on dopamine,
motivation, and drive.
But what I pointed
out is that, if you
are somebody who tends
to experience difficulty
with motivation-- that
so-called dopamine
stacking as I called
it might be something
that you want to avoid.
What's dopamine stacking?
Dopamine stacking
would be combining
a highly caffeinated energy
drink that also includes
the amino acid tyrosine, which
is a precursor to dopamine,
plus loud music plus getting
yourself really ramped up
then an intense workout.
All of that can be great if you
do it every once in a while.
But what you will quickly find
is that the extent to which
your dopamine
peaks also dictates
the extent to which
your dopamine will
drop after that peak.
And when I say drop, I
mean drop below baseline.
So a lot of people find that,
if they stack a lot of things
to peak their dopamine,
then they experience a low,
and it does take some time for
them to return to baseline.
And I highly recommend
not engaging in activities
or consuming compounds that
are in attempt to accelerate
that return to baseline
because all it will do
is drive that baseline
lower and lower.
So this requires
being able to tolerate
a drop in dopamine baseline for
a period of time, et cetera.
Now the reason I'm
bringing this up now
in the context of
this caffeine episode
is I just described a study
in which using caffeine
prior to exercise increases
dopamine after exercise.
And so you might be
saying, especially
if you heard that earlier
episode, wait, isn't
that dopamine stacking?
Aren't you encouraging
me to stack my dopamine?
Well, in some sense, yes.
But keep in mind,
I'm not suggesting
that you do this every
time you exercise.
So just as in that
earlier episode,
I emphasized the fact
that, while stacking
multiple stimuli--
caffeine or energy drinks
and music and et cetera--
for exercise or for mental
work or for any experience
for that matter is OK to do
every once in a while for most
people, you don't want to
get in the habit of doing it
consistently every
time you exercise
or every time you go
out, for instance.
And so you really
want to be cautious.
That is, you want to
protect your both baseline
levels of dopamine and your
peak levels of dopamine.
That said, for people
that want to experience
an increase in mood,
alertness, and performance,
or who want to
condition themselves--
because that's
really what it is.
It's conditioning yourself
by the reinforcing effects
of dopamine to increase
your liking or maybe even
your loving of exercise.
Occasionally, using
caffeine or frequently
using caffeine prior to exercise
is fine but be very careful.
And by being very
careful, what I mean
is pay attention to how you
feel in the hours and days
after that dopamine
increase wears off.
So for instance, if you ingest
caffeine and then exercise
very intensely and you're
feeling great afterwards
but then eight hours
later or the next day,
you're feeling a
little bit low, I
suggest you don't go back and
do the exact same thing right
away.
I would give yourself
a little bit of time
to let that baseline of
dopamine return to normal.
So again, stacking
different things,
chemical and behavioral, in
order to increase dopamine
can be done in a safe way
that's beneficial to you,
depending on your goals.
But be careful about not
stacking too many stimuli
for dopamine too often.
That's the key.
Early in the
episode, I mentioned
one possible
caffeine-consuming schedule
that works very well that
doesn't fortunately subject you
to long 20-day bouts or 5-day or
even 2-day bouts of abstinence.
And that's the every other
day schedule of caffeine.
If you look at the
half-life of caffeine
and you look at its effects
on the dopamine system
and its
performance-enhancing effects
and how a period of abstinence
can, in fact, increase
the performance-enhancing
effects of caffeine--
but also take into
consideration that caffeine
can be habit-forming, and we
can develop a sort of tolerance
to caffeine.
Well then, what emerges
from all of that
is that being a person
who consumes caffeine
every other day
can actually help
you maximize most of the
positive effects of caffeine
without subjecting you to the
kind of misery that occurs
if you're accustomed
to consuming
caffeine every single day and
then suddenly go into a 2 or 5
or 20-day abstinence.
So I myself have never tried
an every other day caffeine
approach, although
I'm considering
doing it based on the
literature that I've read.
And I'm considering doing it
in a very specific way, which
would be to only consume
caffeine on the days in which I
resistance train.
And since I tend to do that
about three or four days
per week organized in a way
that's every other day-- again,
if you want to see the exercise
schedule that I follow,
including cardiovascular
exercise and weight
training and all the reasons
and rationale for what I do
and how it maps on to the
scientific literature,
relate to health span and
lifespan, vitality, et cetera,
you can find that
at hubermanlab.com.
And we had a tool
kit for fitness
that ought to be posted to
our website before long.
The every-other-day schedule
of caffeine intake, to me,
seems like the most
rational one if one
wants to maximize on the
performance-enhancing effects
of caffeine without suffering
the effects of caffeine
withdrawal that are
associated with being
a regular consumer of
caffeine and then stopping
caffeine intake, such as
headache and irritability
and so forth.
Not I nor anyone
in my life wants
me to experience
those effects, and I'm
sure you don't
want to experience
those effects for you either.
So if you're
somebody that decides
to try the every
other day protocol
or you are somebody who's
already doing that protocol,
please let me know what your
experiences with that are.
At least by my read of
the literature on caffeine
and it's
performance-enhancing effects
but also the effects of caffeine
on neurotransmitter and hormone
systems, the every-other-day
caffeine schedule
does seem to be the most
rational and scientifically
grounded one in order to
maximize on all those effects.
In addition to so-called
performance-enhancing effects
of caffeine, there are also
the well studied and now fairly
well mechanistically understood
pro-health effects of caffeine.
Now, here when I talk about
pro-health effects of caffeine,
I want to be very clear that,
if your schedule of caffeine
intake--
that is, your timing
of caffeine intake
or anything else
for that matter--
offsets getting regular
high quality sleep
of sufficient duration,
well, then you
are undermining the pro-health
effects of that thing.
This is true for exercise.
This is true for caffeine.
This is true for
supplementation.
This is true for
prescription drugs.
Again, you don't want to
be neurotically attached
to the idea that you have to
get perfect sleep every night
because that's simply not
true but is absolutely
the case that anything, whether
or not it's good for you
or bad for you in the short
term, that disrupts your sleep
because of the timing in which
you're doing that thing is
going to undermine your
immediate and long-term health
before long.
So with that said,
there are several well
described health-promoting
effects of caffeine ingestion.
And once again, when I
say caffeine ingestion,
I'm referring to that 1 to
3 milligrams per kilogram
of body weight dosage.
There are really nice studies
showing that being a regular
consumer of caffeine can help
offset some of the probability,
some of the probability
of developing
Parkinson's and maybe
Alzheimer's-related dementia
as well.
These are not terribly
controversial data
because of the
fact that caffeine
is known to increase the
release of those catecholamines,
dopamine, epinephrine, and
norepinephrine, as well
as acetylcholine.
All those neurotransmitter
and neuromodulator systems
are the ones that are
known to be defective
in Parkinson's and
Alzheimer's, although there
are other transmitter
and hormone systems that
are defective as well.
There are beautiful reviews
on the neuroprotective effects
of caffeine and
neurodegenerative diseases.
They're quite extensive.
And I'll just refer you to one
and the references therein,
and we'll provide a link to
this in the show note caption.
So the title as the
topic at hand suggests
is the neuroprotective
effects of caffeine
and neurodegenerative diseases.
This was published in 2016.
I'm sure there have been
other reviews since then,
but it includes many, many
quality references and studies,
both in animals and in
humans, pointing to the fact
that specific enzymes
that are associated
with the health of, in
particular, dopamine neurons
are made more robust by
regular ingestion of caffeine.
It also points to the
fact that the increase
in dopamine receptors
that is induced
by regular ingestion of caffeine
that I referred to earlier
is another way in which
dopamine, however many dopamine
neurons remain around in people
with Parkinson's or people
who are aging that lose
dopamine neurons naturally,
that dopamine can have
its maximal effect because
of the increase in receptors for
dopamine that caffeine induces.
And there are other
biological mechanisms
that further
support why caffeine
ought to be
neuroprotective, including
its effects on the
acetylcholine system, which
is one of the major
systems disrupted
in Alzheimer's dementia.
So in other words, it
makes perfect sense
as to why caffeine would
be neuroprotective.
Caffeine has also been
shown to diminish headache,
particularly when taken in
combination with aspirin.
And that's because of the
effects of caffeine and aspirin
on blood flow.
There's also evidence
that caffeine
can provide brief but
substantial relief from asthma.
So I wouldn't want people
to rely on caffeine
as a lifesaving approach
to an asthmatic attack.
That said, for people that
suffer from minor asthma,
that caffeine intake--
again, of the dosages
that we talked
about before has been
shown to alleviate some
of the major symptoms
of asthma for anywhere
from one to four hours.
And I know this is of relevance
to a lot of people out there.
Because caffeine increases
the catecholamines
and in particular because
caffeine increases
dopamine transmission in
the prefrontal cortex--
this area of the brain that's
associated with focus and rule
setting and context
and task switching--
caffeine is known to
improve focus and alertness,
in particular, in
people who have
symptoms of ADHD or other
attention and focus issues.
Now caffeine alone
does not appear
to be as potent for
the treatment of ADHD
as are things like Ritalin,
Adderall, modafinil,
or modafinil and Vyvanse.
If you would like a sort
of head by head comparison
of prescription
drugs, supplements,
and things like
caffeine as well as
coverage of behavioral tools
and nutritional tools, et cetera
that can positively offset
some of the symptoms of ADHD,
please see the episode
that I did on ADHD.
Again, that's available at
hubermanlab.com in all formats.
But that said, caffeine
does increase focus,
and it does it through a
number of different mechanisms,
not the least of which is to
increase dopamine transmission
in the forebrain just as a drug
like Ritalin or Adderall would,
although not to the same
extent as a drug like Ritalin
or Adderall does.
Before we close today, I do
want to just briefly return
to the reinforcing
effects of caffeine
that we talked about earlier.
This study on the
honeybees that showed
that bees prefer certain vectors
because they contain caffeine.
Even though they are not aware
that those vectors contain
caffeine, they just come to like
the feeling that those nectars
provide them so much
that they associate that
in a subconscious way with
the flowers themselves,
and they come to
like those flowers.
Or human beings.
For instance, children that
ingest caffeinated beverages
come to adore the taste
of those beverages.
And beautiful studies have been
done that describe how children
and adults truly cannot
distinguish between the taste
of a caffeinated and
noncaffeinated beverage.
And caffeine can be placed
into essentially any beverage
in order to give us a preference
for that beverage or food.
In fact, the studies have
been done with yogurt.
If you put caffeine into
yogurt of different flavors--
even plain yogurt which
most kids don't like--
they will come to prefer
whatever flavor contain
the caffeine even
if then you remove
the caffeine from that flavor.
Now eventually, their
preference for that flavor
will be extinguished,
but all of this
is just to say that so many
of the things that we like,
whether or not it's coffee or
tea or a given flavor of food
or a given experience
or even exercise,
occur because we ingest
caffeine in conjunction
with those activities.
Now these are not tricks
that your nervous system
plays on you.
These are real
neurochemical-reinforcing
effects.
And I think that we
would all do well
to think about and to leverage
these reinforcing effects
much in the same
way we would do well
to think about and hopefully
not leverage aversive effects
of certain compounds, right?
The simple way to put
this is I or anyone
could get you to dislike
something, someone,
or some place by making you feel
slightly less good, lower mood.
I don't even have to make you
feel nauseous but less good
after ingesting
something or having
a certain kind of interaction or
being in a certain environment,
very straightforward to do
that, because of the way
that your nervous system
is wired for conditioning.
However, there's the
positive side of all this,
which is that it's very
straightforward to reinforce
the experience of a given
food, including its taste,
but all the context around it,
the container, the texture,
the people you consume it
with, where you consume it,
et cetera.
For instance, I
wonder why we are not
pairing caffeine with broccoli.
And here I'm not suggesting
that people actually
do that experiment or
play that trick on people,
but you have to sort of
imagine that, if caffeine
is this incredible reinforcer
of all sorts of things,
in particular, things that we
ingest and would want to ingest
more of if it's paired
with caffeine, well then,
you actually can use
caffeine as a tool
to increase reinforcement
of different things.
And you can avoid caffeine as a
way to further reinforce things
that you would like to stop.
And here I'd like to just give
the example of sugar cravings.
A lot of people ask me, how
do I avoid sugar cravings?
I've talked about the use
of L-glutamine for that.
I've talked about
making sure you're
getting enough essential fatty
acids and essential amino acids
as a way to reduce
sugar cravings.
Please note,
however, that if you
are somebody who likes to have
your sugar, whether or not
it's a piece of chocolate
or your dessert, et cetera--
I'm not saying that's
bad, but if you're
trying to reduce your sugar
cravings, ask yourself,
are you ingesting sugar
along with caffeine?
Could be the caffeine contained
in that sugar-containing food
like chocolate.
Or it could be
that you're having
a cup of coffee along
with your pastry,
and then you're struggling
with sugar cravings.
Well, think about it.
You're not just being reinforced
by the sugar and the effects
of sugar on dopamine
which are real
and both conscious
and subconscious
through the gut to the
brain dopamine system
and direct on the
brain dopamine system.
But by coingesting
caffeine, you are also
further enhancing the
reinforcing effects of sugar.
The flip side to all of this
is that you could use caffeine
as a way to increase your
appetite for certain things.
I actually know somebody.
I won't reveal who
this person is,
but they are quite
prominent podcaster
who ingests 125 to 150
milligrams of in tablet
form along with herbal
tea and use this
as a way to develop a
preference for herbal tea
because they found that
coffee was giving them
other effects that
weren't good for them.
So it works quite
well in animals,
and it works quite
well in insects.
And it works quite
well in humans.
I suppose animals,
insects, and humans
are all animals at the end of
the day, so no surprise there.
But it all underscores the
extent to which caffeine
is an absolutely
fascinating molecule.
I mean, its ability to
offset the sleepiness system,
if you will, this
adenosine system,
and to control our
schedules in that way
to essentially take a
withdrawal against the bank that
is adenosine and
then pay that back
later in the form of
getting sleepy later as
opposed to when we
want to be alert,
its ability to enhance
focus, alertness, and mood.
And if taken after trying to
learn something and remember
it, to enhance
memory, especially.
And its ability to increase
VO2 max, increased strength.
We didn't even talk
today about it,
but I'll just briefly
mention that caffeine
ingested in the sorts of
doses we talked about earlier.
Because its effects on
the neuromuscular system
and the calcium system
associated with neuromuscular
exertion and fatigue can
increase peak power output
and muscle contractability.
It's enhancing
performance there as well.
And, of course, caffeine
does a number of other things
just generally related to
overall and basal level of mood
and alertness, not
the least of which are
these increases in dopamine.
So caffeine is really
an incredible molecule.
It's affecting all these
various neurotransmitter
systems but not haphazardly.
It's increasing dopamine and
acetylcholine in the forebrain
to increase attention.
It's reducing fatigue.
It's improving mental
and physical performance
for some obvious and some
not so obvious reasons.
And what I think is among the
more miraculous and powerful
effects of caffeine, it is
a potent, potent, potent
reinforcer of things, foods,
people, and experiences.
And it's one that you can
leverage in any direction
that you like once
you understand
the way that caffeine exerts
those reinforcing properties.
So today, I've really tried
to cover as much as I could
about the mechanisms of caffeine
action in the brain and body,
as well as tools and
schedules and dosages
in which you can leverage
caffeine in order
to meet your
physical performance,
mental performance, and
frankly mental health,
and overall health goals.
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