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Welcome to the Huberman Lab Podcast,
where we discuss science
and science-based tools for everyday life.
I’m Andrew Huberman,
and I’m a professor of neurobiology and ophthalmology
at Stanford School of Medicine.
Today, we are discussing breathing.
Now, breathing is something that we are all familiar with
because, frankly, we are all doing it right now,
and we do it during our waking states
and while we are asleep.
And most of us have probably heard
that breathing is essential to life.
We hear that we can survive without food
for some period of time,
maybe even up to a month or more,
that we can’t survive that long without water,
but we could survive a few days without water,
depending on how well hydrated we are
when we go into that water deprivation
and the heat of the environment we happen to be in,
but that we cannot survive without breathing
for more than a few minutes,
and that if we cease to breathe,
that our brain and our bodily tissues will die.
And in fact, that is true.
However, despite everybody’s knowledge
that breathing is essential to life,
I don’t think that most people realize
just how important how we breathe is to our quality of life.
And that includes our mental health,
our physical health, and what we call performance.
That is our ability to tap into skills,
either physical or cognitive,
in ways that we would not be able to otherwise
if we are not breathing correctly.
So today we are going to talk about
what it is to breathe correctly,
both at rest, during sleep,
in order to reduce our levels of stress,
in order to wake up or to become more alert deliberately,
and many, many other things,
including how to stop hiccuping.
This is one of the most searched for topics on the internet.
Today, I will teach you the one method
that is actually linked to science.
No, it does not involve drinking a glass of water backwards
from the opposite side of the cup
or holding your breath in any kind of esoteric way.
It actually relates to the neural mechanisms,
that is the brain to body connections,
that cause the hiccup.
Hiccup is a spasm of that neural circuit,
and I’ll teach you how to turn off that neural circuit
in one try.
And that’s not a technique I developed.
It’s a technique that’s actually been known about
for several centuries,
and we now know the underlying mechanism.
So today’s discussion will give to you many tools
that you can apply.
All of these tools are, of course, behavioral tools.
They’re completely zero cost.
And in telling you how those tools work,
you’ll learn a lot about how the breathing,
AKA the respiratory system, works
and how it interfaces with the other organs
and tissues of the body, in particular, the brain.
In fact, one of the most important things
to understand about breathing right here at the outset
is that breathing is unique among brain and bodily functions
in that it lies at the interface between our conscious
and our subconscious behavior,
and it represents a bridge, literally, in the brain
between the conscious and the subconscious.
What do I mean by that?
Well, breathing does not require
that we pay attention to our breathing
or that we are even aware that we are breathing.
It will just carry on in the background,
either normally or abnormally,
and I’ll teach you what normal and abnormal breathing is
in a little bit.
However, breathing is unique among brain
and bodily functions in that at any moment,
we can consciously take control of how we breathe.
This is an absolutely spectacular
and highly unusual feature of brain function.
For instance, your digestion is carrying on
in the background right now,
whether or not you’ve had food recently or not,
but you can’t simply control your digestion
by thinking about it in a particular way.
In fact, most people can’t even control their thinking
by trying to control their thinking.
That actually takes some practice.
It can be done, a topic for a future episode.
However, breathing is unique.
Breathing will carry on involuntarily, subconsciously
in the background, as I said before,
but if at any moment you want to hold your breath
or inhale more deeply or vigorously
or exhale longer than you inhale, you can do that.
Very few, if any other neural circuits in your brain
and body allow that level of control.
It turns out that level of control is not an accident.
It has been hypothesized that by controlling breathing,
the brain is actually attempting to control
its own state of mind.
Now, the way this was originally stated
in a scientific research paper was a little bit different.
It was a little bit more physiological.
The statement was the brain by regulating breathing
controls its own excitability.
Excitability in the context of neurobiology
is how able the brain is to take in new information or not,
how able the brain is or not to turn itself off,
to go to sleep and to regulate its own levels
of anxiety, focus, et cetera.
If that seems a little bit abstract,
I’ll make it simple for you.
By changing your pattern of breathing,
you can very quickly change
what your brain is capable of doing.
In fact, a little bit later,
I’ll tell you that while you inhale,
you are far better at learning and remembering information
than during an exhale,
and it is a very significant difference.
Does that mean you should only inhale and not exhale?
No, of course not.
I’ll teach you how to breathe
for the sake of learning and memory,
as well as for physical performance
and a number of other things.
So hopefully I’ve been able to highlight for you
the importance of breathing, not just for life,
because yes, breathing is essential for life,
but that the subtleties of how we breathe,
the duration and intensity of our inhales and our exhales,
how long we hold our breath between inhales and exhales,
very critically defines our state of mind
and our state of body,
what we are able to do and what we are not able to do.
And the great news is we can control our breathing
and in doing so control our mental health,
physical health, and performance.
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.
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Let’s talk about breathing.
And of course we breathe in order to bring oxygen
into the body,
but we also breathe to remove certain things from our body,
in particular carbon dioxide.
So the main players in today’s discussion
are going to be oxygen and carbon dioxide.
Now, a common misconception is that oxygen is good
and carbon dioxide is bad.
That’s simply not the case.
Let’s just take a step back from that statement
and let’s think about this.
When we breathe in, we are largely breathing in air
in order to bring oxygen into our body.
And we can just stop right there and say,
why do we breathe at all?
Why can’t we just get oxygen from the world around us?
Well, it’s because oxygen can’t diffuse through our skin
into the deeper cells of our body.
Other single cell and very simple organisms
can actually bring oxygen into their system
without the need to breathe.
But we have to breathe in order to bring oxygen
to the cells that reside deep in our body.
In particular, our brain cells,
which are the most metabolically active cells in our body
require a lot of oxygen.
And those brain cells are sitting, of course, in the brain,
which is encased in the cranial vault, the skull.
And so oxygens can’t simply pass to those cells.
So we need to have a system
that will deliver oxygen to those cells.
We also need a system,
which turns out to be the breathing or respiratory system
that can offload or remove the gas
that we call carbon dioxide.
Not because carbon dioxide is bad,
but because too much of it in our system is not good.
In fact, much of today’s discussion
will also center around the common misconception
that carbon dioxide is something that we want to get rid of.
You don’t want to get rid of too much carbon dioxide
or else you can’t actually get oxygen
to the cells and tissues of your body in an efficient way.
So you need oxygen and you need carbon dioxide in your body.
You also need to be able to offload or remove carbon dioxide
and bring in oxygen in the correct ratios
so that you can perform the kind of mental functions
and physical functions that you want to.
So if we just dial out even further,
we say, what are the key components of breathing?
What are the elements within the body
that allow us to bring oxygen to the tissues and cells
as is required and remove carbon dioxide from the body
as is required and yet keep enough carbon dioxide around
in order to allow oxygen to do its thing?
Well, that breathing or respiratory apparatus
has two major components.
And I’m going to just briefly describe those.
And as I do this, I really want to highlight the fact
that anytime you’re thinking about biology
and physiology in particular,
whether or not it’s about the brain or the liver
or the gut microbiome,
it’s useful to categorize things
either as mechanical mechanisms or chemical mechanisms.
What do I mean by that?
Well, let’s just take the analogy of hunger.
There are mechanical mechanisms
that tell us when we should eat.
For instance, you have neurons, nerve cells in your gut
that signal how stretched or non-stretched
the walls of your stomach are, right?
How full or how empty your gut is
and send that information to the brain
to make you feel to some extent hungry or not hungry.
In general, when our stomach is very full,
especially if it’s very distended, even with liquid,
it suppresses our hunger.
Whereas when our stomach is devoid
of that mechanical pressure,
especially for a number of hours,
it tends to trigger hunger by signaling
via neurons to the brain.
In addition, there are chemical signals
that go from the gut to the brain.
For instance, we have neurons in our gut
that can detect the presence of amino acids
from proteins that we eat,
fatty acids from the foods that we eat, the lipids,
and sugars, different forms of carbohydrate.
The neurons in our gut are paying attention to
or respond to how much amino acid,
fatty acid, and carbohydrate is in our gut
and send signals to the brain
to either stimulate or suppress hunger.
So those are chemical signals
that are being passed from gut to brain
and they work in parallel with the mechanical signals.
And this idea of in parallel with,
again, is a very common theme in biology,
especially neuroscience.
The term parallel pathways refers to the fact that
anytime there’s a critical bodily function,
it’s very unlikely that just one type of information,
like just mechanical information, is going to be used.
Almost always, it’s going to be mechanical
and chemical information.
I could pick a number of other examples.
For instance, if you want to avoid damaging your skin
or other tissues of your body, which is essential to life,
well, then you have mechanical information about,
for instance, whether or not something is pinching
or ready to pierce your skin.
That’s mechanical information.
It’s sent via specific neurons up to the brain
to signal a retraction reflex.
If you move your limb away
from wherever that intense pressure is coming.
You also have chemical sensing in your skin,
the presence of things that elicit a burn
or that elicit itch or that elicit extreme cold.
All of that chemical information
is being signaled up to the brain as well in parallel.
So parallel pathways is a common theme.
So when we’re thinking about the respiration,
aka the breathing system,
we also need to look at the mechanical system.
What are the different components of the nose,
the mouth, the lungs, et cetera,
that allow oxygen to be brought in
and carbon dioxide to be removed from the body,
but not too much carbon dioxide removed
to allow breathing to work as efficiently
and as optimally as possible.
And then we also need to look at the chemical systems
of the lungs, the bloodstream,
and how different cells use oxygen and carbon dioxide
in order to understand that as well.
If you can understand the mechanical
and chemical aspects of breathing,
even just at a top contour,
well, then the various tools that I discussed
during today’s episode,
such as the ability to calm yourself down most quickly
by doing what’s called a physiological sigh.
I’ll go into this in more detail in a little bit,
but this is two very deep inhales through the nose.
So the first one is a long inhale.
And then the second one after that is a quick sharp inhale
to maximally inflate your lungs,
followed by a full exhale through the mouth
to lungs completely empty.
So it’s big inhale through the nose,
then short inhale through the nose immediately after that
in order to maximally inflate the lungs.
And then a long exhale through the mouth
until your lungs are empty.
You will understand why that particular pattern
of breathing and not simply one inhale
or not simply an inhale through the nose
and an exhale through the nose as well
is optimal for reducing your stress quickly.
That double inhale through the nose
followed by a long exhale through the mouth
works to reduce your levels of stress
and lower your levels of so-called autonomic arousal
very fast in real time.
And it works better than any other known approach.
It’s not a hack.
This is actually something that your body
has specific neural circuits to do.
And it actually performs during sleep on a regular basis
and even throughout the day.
And that you can perform voluntarily.
And it works so well to reduce stress very quickly,
not because it brings in the maximum amount of oxygen
and removes the maximum amount of carbon dioxide,
but rather because it optimally balances
oxygen and carbon dioxide.
If you understand the mechanical
and chemical aspects of breathing,
then you will understand exactly why
that particular pattern of breathing,
the so-called physiological sigh,
is the most efficient way to rapidly reduce stress
in real time.
If you can understand the mechanical
and chemical aspects of breathing,
you will also understand why most people are over-breathing,
that is they’re breathing too often,
even if they’re breathing in a shallow manner,
they’re breathing too often,
and they are blowing off or removing
too much carbon dioxide.
And if you understand that carbon dioxide
is critical for the way that oxygen is delivered
from the bloodstream to the tissues of the body,
including the brain,
well, then it will make very good sense
as to why people who are breathing too much
don’t actually experience all the effects
of elevated oxygen,
but rather they’re putting their body
into what’s called a hypoxic state.
They’re not getting enough oxygen
to the tissues of their body, in particular, their brain.
And this is true, not just for people who are obese
or who suffer from sleep apnea,
or although that’s certainly the case,
but for people that have, believe it or not,
certain personality types.
We’ll talk about breathing and personality type
and actually how breathing has been shown
to alter personality.
That’s right, breathing can alter personality
in positive ways that allow anyone
to show up to the various social
and non-social endeavors of their life
with more calm, more focus, alertness,
and improve their overall health.
Okay, so let’s talk about
the mechanical components of breathing.
It’s really quite simple.
You’ve got your nose, obviously,
and you’ve got your mouth.
And a little bit later,
we’ll talk about the incredible advantages
of being a nasal breather most of the time,
but also the incredible advantages
of using your mouth to breathe,
both for inhales and exhales
during particular types of endeavors.
And we’ll get back to that a little later.
But for the meantime,
the only two ways to bring air into your system
are through your nose and through your mouth.
We also have the larynx,
which is a rigid tissue or pipe
that brings the air from the nose and mouth
down to the lungs.
Now, that word rigid is really important here
because what we will soon learn
is that your lungs basically act like a pump.
You sort of know this already,
but these are two big bags, basically,
that can fill with air or that can squeeze air out.
Now, what most people don’t realize
is that the lungs are not just two big bags of air.
Your lungs are actually two big bags of air
that inside of them have hundreds of millions
of little sacs that are called the avioli of the lungs.
And by having those hundreds of millions of little sacs,
you increase the surface area of the lungs.
And by increasing the surface area,
you allow more oxygen to pass from the air in your lungs
into the bloodstream than if you didn’t have those sacs.
And you allow more carbon dioxide
to move from the bloodstream into those sacs of the lungs.
And then when you exhale,
the carbon dioxide can be removed.
Okay, so those little sacs we call avioli of the lungs
are an important part of the mechanical aspect of breathing.
We’ll get to a little bit later.
Okay, so at a first pass,
the mechanical aspects of breathing
are really straightforward, right?
You can breathe through your nose,
you can breathe through your mouth,
goes down through the larynx.
I told you the larynx is a rigid pipe.
The lungs are not rigid.
They can expand and they can contract like a pump
to bring in air or to expel air.
Keep in mind that the lungs
do not have any muscles themselves.
So we need muscles that can either squeeze the lungs
or that will allow the lungs to expand.
And there are two general groups of muscles that do that.
And they are the diaphragm
and the so-called intercostal muscles.
The diaphragm is a thin muscle
that sits below the lungs and above the liver.
And when we inhale,
provided that we are using
what’s called diaphragmatic breathing,
that diaphragm contracts.
And when it contracts, it moves down,
which allows more space for the lungs to inflate with air.
Now, the intercostal muscles
are the muscles between our ribs.
A number of people probably don’t realize this,
but your ribs, of course, are bone,
but in between those bones, you have muscles.
And the intercostal muscles, when you inhale, contract,
and that allows your rib cage to move up
and to expand a bit.
Now, I think, again,
people probably don’t realize
that your ribs are not fixed in place.
They can actually get further
and closer apart from one another.
So when you inhale, your rib cage actually moves up.
Sometimes the shoulders will move up as well.
And that’s because those intercostal muscles
are contracting.
Now, muscles can’t move on their own.
They are controlled by nerves.
We’ve got the nose, the mouth, the larynx, and the lungs.
The lungs have all those little alveoli in them.
And as I told you, we’ve got the diaphragm
as a muscle to move the lungs,
and we have the intercostal muscles to move the ribs,
which can allow the lungs to expand.
Again, we’re just on the mechanical components of breathing.
But because muscles can’t move themselves,
you should be asking what moves the muscles.
And it’s really nerves that control muscles.
So whether or not you’re contracting your biceps
or you’re walking and you’re contracting your quadriceps
and your hamstrings and your calf muscles,
it’s neurons, nerve cells that control that.
There’s a specialized nerve called the phrenic nerve,
P-H-R-E-N-I-C, phrenic nerve that comes out of the neck.
And when I say it comes out of the neck,
what I mean is that they’re little neurons
that reside in the brainstem, in the back of your brain.
And they send little wires that we call axons
down and out of the neck.
They go close to the heart and a little bit behind it,
and they go down and they form synapses.
That is, they form connections with the diaphragm.
And when those neurons release neurotransmitter,
which are little chemicals,
the diaphragm contracts and it moves down.
So we say that the phrenic nerve is a motor nerve.
It’s designed to move muscle.
However, the phrenic nerve,
like a few other nerves in the body,
is interesting in that it has not just motor nerves
in there, neurons that control the contraction of muscles,
it also can sense things.
There has sensory neurons.
So it also sends connections down to the diaphragm
and actually down deep into the diaphragm
and close to the liver.
And note that I said liver twice now already,
and we’re going to get back to this later
when we talk about physical movement and cramps of the body.
Those sensory neurons dive deep into the diaphragm,
and then they go back up to the brain,
and they allow you to sense where the diaphragm is.
So they’re giving information
about where the diaphragm is in your body.
Now, most of the time you’re not paying attention to this,
but right now you can actually try this,
and I would encourage you to do this.
Diaphragmatic breathing is in many ways
the ideal way to breathe
in that it’s the most efficient way to breathe.
We’ll talk about what we mean exactly
when we say breathing efficiency later.
But the diaphragm is designed to allow the lungs to expand
or to contract the lungs to bring air into the body
or to remove carbon dioxide from the body.
And if you want to know
whether or not you’re using diaphragmatic breathing,
it’s very simple.
If you inhale, probably best to do this through the nose,
but you could do it through the mouth.
If you inhale and your belly moves outward on the inhale,
well, then that phrenic nerve
is controlling your diaphragm properly.
And then when you exhale,
your belly should go in just a little bit.
That’s diaphragmatic breathing.
Now, diaphragmatic breathing is talked about
in the context of yoga.
It’s often talked about as a way to calm down and so on,
but diaphragmatic breathing is just one mode
by which your brain and the phrenic nerve
can control muscle, the diaphragm,
to control the mechanical aspects of the lungs
to bring in air and expel air.
As I mentioned before,
you also have these muscles between your ribs
or the intracostal muscles.
And there’s a separate set of nerves
that allow those muscles to contract
and for your rib cage to expand
in order to create more room for your lungs
to get larger and fill with air
or for your rib cage to contract a bit
when those muscles relax in order to expel air.
I’d like to go on record by saying that
there is no rule that diaphragmatic breathing is better
than breathing where your rib cage moves.
This is a common misconception.
People say, oh, you know,
if your shoulders are going up and down
and your rib cage is moving while you’re breathing,
well, then you’re not breathing right.
And if your belly goes out
and the rest of your body is still while you breathe,
well, then you’re breathing correctly.
I know of zero, in fact, zero minus one data
to support that statement.
You have multiple parallel mechanisms
to control the mechanics of your lungs and for breathing.
And when you’re exerting yourself very hard,
you tend to use both the intracostal muscles
and your rib cage moving,
as well as your diaphragm
in order to bring in a lot of oxygen
and to offload a lot of carbon dioxide.
And when you’re calmer, frankly,
you could use diaphragmatic breathing
or you could use rib cage type breathing
in order to bring enough oxygen into your system.
There’s no real data showing
that diaphragmatic breathing is somehow better or worse.
However, being able to mechanically control
those independently or to combine them
and use them together is of tremendous power
toward regulating your mental and physical states.
And we’ll talk about how to do that a little bit later.
For right now, please understand
that you have these different mechanical components
that allow you to bring oxygen into your system
and to expel air
and to thereby offload carbon dioxide from your system.
Again, we haven’t talked about the gas exchange
of carbon dioxide and oxygen
and how that’s happening in the bloodstream.
We’ll talk about that next.
But the basic mechanical components are pretty simple.
Once again, just to review, it’s nose, mouth, larynx, lungs,
alveoli within the lungs, and then those two muscles,
the diaphragm and the intracostal muscles of the ribs.
And one thing I failed to mention
is why it’s so important that that larynx be rigid,
that it’s a tube that is very rigid.
And the reason for that is that unlike the lungs,
which you want to act as sort of a bellow pump
where you can deflate it and inflate it
in order to move air in and out,
the larynx needs to be rigid so that it doesn’t collapse
while you’re bringing air in and out.
You can imagine that if it was a very flimsy tube
or the walls of the larynx were very flimsy and thin,
well, then you can imagine breathing in very vigorously
and it would shut like a tube
that suddenly flattens on itself, which would not be good.
So the fact that the larynx is rigid
is actually a very crucial part of this whole system.
The other important aspect of this system
as it relates to the mechanics of breathing
is the fact that your nose and your mouth
have different resistances to air.
You can probably notice this right now
if you were to, for instance, breathe in through your mouth
and only through your mouth
versus breathe in through your nose.
Some of you perhaps have a harder time
breathing in through your nose.
By the way, it’s perfectly normal
that one or the other nostril
would be harder to breathe through
or easier to breathe through
and that that switches across the day.
It has to do with the flow of mucus
and cerebrospinal fluid and intracranial pressure,
totally normal.
Many people out there think they have a deviated septum
who don’t actually have a deviated septum.
A little bit later, we’ll talk about
how to repair a deviated septum without surgery
because that actually is possible in many, not all cases
and is immensely beneficial to do.
But what we know is that breathing in through the nose
is a little bit harder
and it’s supposed to be a little bit harder.
However, because it’s a little bit harder,
because there’s more resistance, as we say,
you’re actually able to draw more force
into these mechanical aspects of the breathing apparatus
and actually bring more air into your lungs.
You can try this right now.
Try breathing in through your mouth
to maximally inflate your lungs
and try and do it through mostly diaphragmatic breathing,
just for sake of example.
In other words, try and breathe in through your mouth
and as you do that, have your belly expand
and maximally inflate your lungs.
I’ll do it right now with you
so that we can do it together
and I can prove to everyone
that I’m just as deficient in this as you are.
Okay, so I can inflate my stomach doing that,
but now try doing it with your nose
and please do exhale before you try doing it with your nose.
With your nose, you’re going to feel more resistance,
but you’ll notice that you can inflate it
quite a bit further.
And you’ll feel your entire cavity, your belly,
and maybe even in your lower back,
sort of fill with some pressure.
So the increased resistance actually allows you
to draw more air into the system.
This turns out to be very important
and it also wipes away a common misconception,
which is if you’re somebody who has challenges
breathing in through your nose,
that somehow you should avoid breathing in
through your nose.
Actually quite the opposite is true
and we can go a step further and say
that if you have challenges breathing in through your nose,
chances are that’s because the increased resistance
of breathing in through your nose,
provided it’s not completely occluded,
is going to allow you to bring more oxygen into your system.
This will turn out to be useful later
when we explore different techniques, for instance,
not just to calm down quickly,
but to elevate your energy quickly,
to remove a cramp during exercise,
and a number of other things that breathing can be used for
that can be immensely useful
for mental and physical challenges.
I’d like to take a quick break
and acknowledge one of our sponsors, Athletic Greens.
Athletic Greens, now called AG1,
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I’ve been taking Athletic Greens since 2012,
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The reason I started taking Athletic Greens
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Our gut is very important.
It’s populated by gut microbiota,
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So now let’s talk about the chemical aspects of breathing,
and the two major players in this discussion are oxygen,
which all the cells and tissues of your body need,
and carbon dioxide,
which all the cells and tissues of your body need.
In fact, carbon dioxide plays critical roles
in delivering oxygen to your cells,
and without carbon dioxide,
you’re not going to get enough oxygen
to the cells and tissues of your body.
That said, if carbon dioxide levels are too high,
that is very problematic.
In fact, one of the ways that one can reliably induce panic
in anybody is to have them breathe air
that contains too much carbon dioxide,
so much so that for people that lack a so-called amygdala,
many of you have probably heard of the amygdala,
this is a brain area that’s associated with fear
and threat detection,
even in people who completely lack amygdalas
on both sides of the brain,
because they were removed,
because they had epileptic seizures there,
and therefore those people are completely unafraid
of things that they ought to be afraid of,
like heights, poisonous snakes,
any number of different things, dangerous to humans.
Well, if those people breathe an excess amount
of carbon dioxide, they immediately have a panic attack.
What that tells us is that, again,
there are parallel mechanisms,
there’s redundancy in the system to protect ourselves
from having too much carbon dioxide in our system.
So we need enough carbon dioxide and enough oxygen
in our system, but not too much.
The way that’s accomplished is that, of course,
we breathe in air, our lungs inflate,
and if you recall those little alveoli of the lungs,
those little sacs, oxygen can actually move
from the air into those little sacs,
and then from those little sacs into the vasculature.
The vasculature are the capillaries, the veins,
and the arteries of the body,
because the walls of those little alveoli
are exceedingly thin, and they have tons
of little capillaries that go into them
and are all around them.
So this is amazing, right?
There’s oxygen literally passing from inside
of these little sacs in our lungs,
because we inhaled the oxygen, from the air,
into the bloodstream, and then that oxygen gets bound up
by proteins in the blood, in particular, hemoglobin,
and hemoglobin then delivers oxygen
to the various cells and tissues of the body.
However, oxygen can’t just hop on hemoglobin
and cruise along with hemoglobin until it gets
to, say, your brain and then hop off.
It doesn’t work that way.
You require carbon dioxide in order
to liberate oxygen from hemoglobin.
Carbon dioxide has this incredible property
of actually being able to change the shape of hemoglobin.
Hemoglobin is shaped as a sort of a cage
around oxygen molecules, and when it’s in that cage shape,
the oxygen can’t be liberated.
So you’ve got oxygen and hemoglobin bound to one another,
moving through your bloodstream,
but if a tissue needs oxygen,
there needs to be carbon dioxide present
to open up that cage, and that’s what carbon dioxide does.
It allows that cage to change shape,
and then the oxygen can be liberated
and then can be delivered to the tissues,
whether or not that’s brain tissue or muscle tissue,
so on and so forth.
And so those are the major chemical components of breathing.
There are a few other aspects related
to the chemical components of breathing,
such as the fact that carbon dioxide is strongly related
to how acidic or how basic your body is in general.
So for instance, if carbon dioxide levels go way down,
your blood pH goes way up.
That is, you become more alkaline.
Now, for many people, the word pH
and the whole concept of pH immediately starts
to evoke anxiety in and of itself.
pH is actually very simple.
You want the body basically to be at a pH of about 7.4.
There are some regions of your body,
in particular along the gut,
which that number is importantly different
in order for digestion to work properly.
You’ve all heard of the gut microbiome,
the little microbes that provided you have enough of them
and they’re diverse enough,
allow your brain and body to function optimally
at the level of immune system, hormone system,
brain, et cetera.
Well, in the gut,
you want the pH sometimes to be slightly more acidic,
because when it’s more acidic,
the little microbiota flourish far more
than if it were more basic.
But basically you want the rest of the body
to be at about pH 7.4.
If carbon dioxide levels go too low,
the pH increases in a way that you might say,
oh, well, that’s bad,
but that actually allows more oxygen to be available
to the tissues of your body, at least temporarily.
We’ll talk about this a bit more later.
If I’m losing any of you, just hang in there
because we’re almost done with this whole business
of the mechanics and the chemistry of breathing.
And then we can get into the tools
and revisit some of this later
to clean up any misunderstandings that may have arisen.
But as we’re talking about carbon dioxide over and over again
and how key it is to have carbon dioxide
and the problems with it going too high or too low,
you should probably be asking yourself
what actually makes carbon dioxide go too low, right?
We know that we breathe in oxygen
and then it can pass from the lungs
and the alveoli into the bloodstream.
And then we need carbon dioxide to liberate oxygen
from the hemoglobin into the cells and tissues of the body.
And we know that when we exhale,
actually, I haven’t told you this yet,
but you should know that when you exhale,
carbon dioxide is actually taken from the bloodstream
back into those alveoli of the lungs.
And then when you exhale,
it’s expelled through your mouth or through your nose
out into the world.
So the way I just described all that,
inhale, bring in oxygen, exhale, expel carbon dioxide,
pretty straightforward, right?
Indeed it is.
And it also tells you that were you to exhale a lot more
or a lot more vigorously,
you would expel more carbon dioxide.
And in fact, that’s exactly the way it works.
When you hyperventilate,
of course you are inhaling more than usual,
but you are also exhaling more than usual.
So you’re of course bringing in more air
and oxygen to your body,
but you’re also removing more carbon dioxide
from your body than normal.
Carbon dioxide,
because of the ways that it regulates brain state,
in fact, the way in which it regulates the excitability,
literally the ability of your neurons
to engage electrically or not,
it can create states of panic and anxiety,
which is why when you hyperventilate,
you feel an increase in anxiety,
or when you feel an increase in anxiety,
you hyperventilate, it’s a reciprocal relationship.
In fact, I don’t want anyone who has anxiety
or who has panic attacks to try this now,
but for most people, it’s probably safe
as long as you’re not driving or doing something mechanical
or operating machinery that is,
probably safe to do 25 or 30 deep inhales and exhales.
And you’ll notice that by about breath 10,
you’ll start to feel tingly
and you’ll probably feel a little bit more alert.
And again, if you have anxiety or panic attack tendencies,
please don’t do this,
but you will feel an increase in so-called autonomic arousal
and increase in the activity
of your overall sympathetic nervous system,
which has nothing to do with sympathy,
has everything to do with alertness.
You’ll actually deploy adrenaline from your adrenals.
So I’ll just do this now.
You can try this now, again,
provided you’re in a safe place
and you don’t have anxiety or panic attack tendencies.
You will just breathe in through your nose
and out through your mouth.
Remember, we’re breathing in more and more vigorously
and we’re exhaling more and more vigorously
than we normally would.
It goes something like this.
Now, by breath eight or nine or 10,
you’ll notice that your body starts to heat up.
That’s due to a couple of things,
mainly the release of adrenaline from your adrenals.
I’m already feeling a little bit lightheaded.
The lightheadedness is actually because your vasculature,
the capillaries and veins,
and to some extent, even the arteries of your body,
and particularly in your brain,
are actually starting to constrict.
So you’re cutting off blood flow to the brain.
Why?
Well, because carbon dioxide actually is a vasodilator.
Normally it exists in your body to keep capillaries,
veins, and arteries dilated
to allow blood to pass through them.
When you hyperventilate,
sure, you’re bringing in a lot of oxygen,
which you think would make you more alert,
and indeed it does,
but you are also expelling a lot more carbon dioxide
than you normally would,
and that’s causing some vasoconstriction,
and you’re going to start feeling tingly in the periphery,
in your fingers and toes, perhaps, or your legs.
You will also notice that you’re feeling more alert
in the brain, but that you might start
to feel a bit of anxiety.
So hyperventilation, yes, brings in more oxygen,
also removes more carbon dioxide.
The removal of excess carbon dioxide
puts you into a state that’s called hypocapnic, right?
Hypoxia, hypoxia is reduced levels of oxygen
relative to normal.
Hypocapnia is reduced levels of carbon dioxide
relative to normal,
and it is those reduced levels of carbon dioxide
that are largely responsible for that elevation in energy,
and at the same time, a feeling of a bit of anxiety,
the constriction of the microvasculature
in the brain and body,
and therefore the feelings of being kind of tingly
and having kind of an urgency to move.
Okay, so by now it should be clear
that we need both oxygen and carbon dioxide,
and across the course of this episode,
I will explain how to adjust those ratios of oxygen
to carbon dioxide,
depending on what your immediate needs are
and what you plan to do next,
whether or not that’s sleep or exercise
or some mental work, et cetera.
Before going any further, however,
there is something I want to touch on
because even though not everyone will experience this,
I think enough people experience it
that it is of interest,
and now’s the right time to touch into what happens
when you go up to a very high altitude,
meaning why it’s hard to breathe
when you get up to high altitudes.
So if you’re close to sea level,
you are getting kind of the optimal balance of oxygen
in the air you breathe.
As you ascend in altitude,
so let’s say you go to 6,000 feet or 10,000
or maybe even 11,000 feet above sea level,
or maybe you’re one of those rare individuals
that climbs Denali or you climb Mount Everest
and you get up there and you notice that
most people are going to wear an oxygen mask.
Why is it that you need an oxygen mask
at those very high altitudes
or when people do these very high altitude skydives
that they need oxygen way up high?
Well, a lot of people will say,
oh, there’s not much oxygen up there,
you know, the air is thinner.
Okay, well, perhaps a better way to think about it
is that remember when we were talking about
the mechanical aspects of breathing
and the fact that the lungs don’t really move themselves,
that they have the muscles, the diaphragm
and the intercostal muscles to move them.
Well, a lot of the reason why your lungs
can fill so readily with air
is that when you don’t have much air in your lungs,
there’s very low air pressure in your lungs
relative to outside you, okay?
So what we mean then is if you were to open up your mouth
or your nose and breathe in,
that is breathe in through your nose or mouth,
what’s going to happen is air is going to move
from high pressure to low pressure.
So it’s very easy to fill your lungs,
even though you need those muscles
to move the various things around
that allow your lungs to fill,
the air is going to go from high pressure to low pressure.
So for those of you listening,
I just took a big inhale through my nose.
And then when you exhale, right,
you’re basically taking the lungs from a state
in which the pressure is really high in the lungs,
you know, high pressure, like a balloon that’s full.
And the pressure in your lungs when your lungs are full
is higher than the air outside.
So it’s pretty easy to expel that air
through the nose or mouth.
When you’re at high altitudes, the air pressure is lower.
And so what happens is when the air pressure
is lower outside your body
and your lungs are not full of air,
you don’t have that really steep gradient
of high pressure outside the body
to low pressure inside your lungs.
And so you actually have to put a lot more effort
into breathing air into your lungs.
You have to really exert a lot of force.
You have to get the diaphragm,
those intercostal muscles working really hard.
You might even find that your shoulders are lifting
with each breath,
because you really have to generate a lot of force
to get enough air and oxygen into your lungs.
Now, an important principle to understand
is that in humans and in some other species,
but really what we’re talking about now as humans,
when you inhale, that’s an active process.
You really need to use those muscles of the intercostals
and the diaphragm in order to inflate the lungs.
But the whole process is made easier
when air pressure outside your body is higher
than it is in your lungs,
because then they’re going to fill up really readily.
Exhaling, at least for humans, is a passive thing.
You just have to relax the diaphragm
and relax the intercostals
and let the ribcage kind of fall back
to its original position.
So inhaling is active and exhaling is passive.
And so what happens is if you’re at a high altitude
and the air pressure is very low,
then you have to put a lot of energy
into breathing air into your lungs
to get an equivalent amount of oxygen into your lungs
and then into the bloodstream.
So that’s why when you arrive at a high altitude location
for the first few days,
you’re going to feel lightheaded, maybe a headache.
You’re also going to have more buildup
of carbon dioxide in your system.
And so the whole balance of oxygen and carbon dioxide
is going to be disrupted.
I mention all that because yes, indeed,
there are some changes in the atmospheric gases
at high altitudes,
and that can impact how much oxygen
you can bring into your system, into your tissues.
But, you know, I’ve heard many explanations
of why it’s hard to breathe
or why you feel lousy at altitude.
Well, you just discovered one reason,
which is that you don’t have that steep high pressure
to low pressure gradient from the outside of the body
into the inside of the body.
The converse is also true.
If you’ve been at altitude for a few days
and you’ve had the opportunity to adjust,
a lot of athletes, for instance, will go train at altitude.
It’s hard for them in the first days or weeks,
and then they get really good at training at altitude.
There are a number of different adaptations that occur
in terms of the amount of oxygen
that can be carried in the blood by hemoglobin
and the interactions between carbon dioxide
and hemoglobin and oxygen
that allow more oxygen to be delivered to the tissues,
such that at altitude, you can function just normally.
But if you then move very quickly from altitude,
say you’ve been training at 8,000 feet or 10,000 feet,
you’ve been hiking up at the high level and you’ve adapted,
and you come down to sea level,
well, for about two to five days,
you’re going to feel like an absolute beast.
You’re going to be able to essentially deliver
far more oxygen to your muscles per breath.
In part, that is because of the way that the hemoglobin
and the oxygen that it’s carrying has been altered
when you were at high altitude,
but it’s also because when you were at that high altitude,
those intracostal muscles and those diaphragms
got trained up quite a bit
and allowed you to generate more air volume
for every breath.
In other words, those muscles got stronger
and you got more efficient at driving the phrenic nerve
consciously to really breathe in a lot of oxygen
so you don’t feel lightheaded, headache, et cetera.
Okay, so that’s a little bit of an aside,
but it’s an important aside, I believe,
because A, it answers a question a lot of people ask
and a lot of people wonder about,
and B, because it incorporates
both the mechanical aspects of breathing
and the chemical aspects of breathing.
I realize it’s a little bit of a unusual circumstance,
but now if anyone asks you
why it’s hard to breathe at altitude,
you know it has to do with this lack of a high pressure
to low pressure gradient across the body
and with the atmosphere outside you.
It’s also an opportunity for me to say
that if you do find yourself at altitude
and you have a headache
or you’re feeling like you just can’t catch your breath,
spending some time really consciously
trying to draw in larger breaths of air,
as much as that might seem fatiguing
and you’ll be short of breath,
it will allow you to adapt more quickly.
And a little bit later in the episode,
we’ll touch on a few methods,
including deliberate hyperventilation
combined with some breath holds
that can allow you to deliver more oxygen to the cells
immediately upon arriving at altitude
so you don’t get quite as much headache,
disorientation, and so on.
So leaving breathing at altitude aside,
let’s all come back down to the same conceptual level.
We can ask ourselves, for instance,
what is healthy breathing and what is unhealthy breathing?
And the first place we want to tackle this
is within the context of sleep.
So when we go to sleep at night, we continue to breathe.
That’s no surprise.
If we didn’t, we would die during sleep.
However, there is a large fraction of the population
that under breathes during sleep.
They’re not taking deep enough or frequent enough breaths,
and therefore they are experiencing
what’s called sleep apnea.
They are becoming hypoxic, hypoxic.
There’s less oxygen being brought into their system
than is necessary.
People that are carrying excess weight,
either fat weight or muscle weight or both,
are more prone to nighttime sleep apnea.
However, there are a lot of people who are not overweight
who also experience sleep apnea.
How do you know if you’re experiencing sleep apnea?
Well, first of all, excessive daytime sleepiness
and excessive daytime anxiety
combined with daytime sleepiness is one sign
that you might be suffering from sleep apnea.
The other thing is if you happen to snore,
it’s very likely that you are experiencing sleep apnea.
And I should mention that sleep apnea
is a very serious health concern.
It greatly increases the probability
of a cardiovascular event, heart attack, stroke.
It is a precursor or sometimes the direct cause
of sexual dysfunction in males and females,
cognitive dysfunction during the daytime.
It can exacerbate the effects of dementia,
whether or not it’s age-related dementia of the normal sort
or Alzheimer’s type dementia,
which is an acceleration of age-related cognitive decline.
If you’re somebody who’s had a traumatic brain injury,
if you’re experiencing a lot of stress,
sleep apnea is going to greatly disrupt
the amount of oxygen brought into your brain and body
during sleep and is going to lead to a number
of nighttime and daytime issues.
So it’s something that really needs to be addressed.
And we’ll get into this a bit more later,
but since I raised it as a problem,
I do want to raise the solution.
One of the major treatments for sleep apnea
is that people will get a CPAP device,
which is this face mask and a machine
that they’ll sleep with.
And while those can be very effective,
not everyone needs a CPAP.
One of the more common methods nowadays
that’s being used to treat sleep apnea,
which is purely behavioral and intervention
and is essentially zero cost
is that people are starting to shift deliberately
to nasal breathing during sleep
because of the additional resistance of nasal breathing.
And because of the fact that there’s far less tendency,
if any, excuse me, to snore when nasal breathing.
Taping the mouth shut using medical tape prior to sleep,
excuse me, putting medical tape on the mouth
prior to going to sleep and then sleeping all night
with medical tape on the mouth is one way
that people can learn to nasal breathe during sleep
and can greatly offset a lot of sleep apnea,
snoring and sleep related issues.
A number of people don’t want to or don’t feel safe
putting medical tape on their mouth prior to sleep.
For some reason, they think they’re going to suffocate,
but of course you would wake up
if you start to run out of air at any moment.
So that’s not so much a concern,
but what they’ll do is they will start to use
pure nasal breathing during any type of exercise
or even just for some period of time
walking during the day or while working.
And again, later we’ll get into the enormous benefits
of shifting to pure nasal breathing
when not exercising hard,
meaning at a rate that you could normally
hold a conversation,
although if you’re pure nasal breathing,
you won’t be holding that conversation
or when simply doing work
or any number of things that are sort of low intensity,
you can train your system to become a better nasal breather
during the daytime through these deliberate actions
of taping the mouth shut
or just being conscious of keeping your mouth shut.
And that in addition to having a number of positive health
and aesthetic effects during the daytime
is known to also transfer to nighttime breathing patterns
and allow people to become nasal breathers
as opposed to mouth breathers during sleep
and to snore less and to have less sleep apnea.
Again, if you have severe sleep apnea,
you probably do need to check out a CPAP.
You should talk to your physician,
but for people who have minor sleep apnea
or sleep apnea that’s starting to take hold,
these other methods of shifting to becoming a nasal breather
are going to be far more beneficial
and far more cost effective
than going all the way to the CPAP,
which by the way,
doesn’t really teach you how to breathe properly
as much as it does adjust the airflow
going into your system.
That’s an important point
that when you shift from mouth to nasal breathing
during sleep,
you’re actually learning and training your system
to breathe properly.
And when I say learning and training your system
to breathe properly, what do I mean?
Let’s put some scientific and mechanistic meat on that.
We already talked about the phrenic nerve,
this nerve that innervates the diaphragm
and that allows for the lungs to fill up
because of the movement of the diaphragm.
What we didn’t talk about, however,
were the brain centers that actually control
the phrenic nerve and control breathing.
Knowing about these two brain areas
and what they do is extremely important,
not just for understanding the content of this episode,
but for understanding all of the tools that we’ll discuss
and indeed your general health
as it relates to respiration.
So there are basically two areas of the brain
that control breathing.
The first is called the pre-Buttsinger complex.
You don’t have to worry about the name so much,
just know that it was named after a bottle of wine
and that it was discovered.
By the great Jack Feldman,
who’s a professor of neuroscience
at the University of California, Los Angeles.
This is one of the most fundamental discoveries
in all of neuroscience in the last hundred years or more,
because this brain area
that Jack and his colleagues discovered
controls all aspects of breathing that are rhythmic.
That is when inhales, follow exhales,
follow inhales, follow exhales.
That’s all controlled by a small set of neurons
in this brainstem area,
so around the region of the neck,
called the pre-Buttsinger complex.
And we really owe a debt of gratitude
to Jack and his colleagues for discovering that area
because it’s involved in everything
from breathing when we’re asleep
to breathing when we’re not thinking about our breathing.
It may have a role,
that is when its function is disrupted,
it may cause things like sudden infant death syndrome.
Believe it or not, it can explain in large part
many of the deaths related to the opioid crisis
because exogenous opioids like fentanyl
and other sorts of drugs, which are opioids, obviously,
bind to opioid receptors on that structure
and shut it down.
Now, keep in mind,
these neurons are designed to be incredibly robust
and are designed to fire, inhale, exhale, inhale, exhale,
no matter if we’re awake or aware, unaware,
or asleep to keep us alive.
Exogenous opioids like fentanyl
and drugs that are similar to that
can shut down that structure
because it’s rich with these opioid receptors,
so it binds to that
and it shuts off the prebotzinger complex,
which is the major cause of death
of people who die from opioid overdoses.
I think a lot of people don’t realize that.
They think, oh, the opioids must shut off the brain
or shut down the heart.
No, it shuts down breathing.
So Jack’s discovery, no doubt,
will lead to some important things
as it relates to addiction.
And hopefully, I think we frankly can expect
that it’s also going to eventually lead to ways
to prevent death in people using opioids
or other types of drugs,
maybe by blocking opioid receptors
in prebotzinger complex
using things like naltrexone, et cetera.
In any event, prebotzinger complex
is controlling inhale, exhale, inhale, exhale
to patterns of breathing.
The other brain center controlling breathing,
again, through the phrenic nerve, right?
It all converges and goes out through the phrenic nerve
and these intracostal muscles
is the so-called parafacial nucleus.
And the parafacial nucleus
is involved in patterns of breathing
where there is not an inhale followed by exhale,
that is, it’s not rhythmic one than the other,
but rather where there is a doubling up of inhales
or a doubling up of exhales
or a deliberate pause in breathing.
So inhale, pause, exhale, pause,
inhale, pause, exhale, pause, this sort of thing.
A little bit later, we’ll talk about
a pattern of breathing called box breathing,
which has a very specific and useful applications
in particular for adjusting anxiety.
And in that case, it involves going
from rhythmic breathing of inhale, inhale, inhale, exhale,
that is relying on the pre-Butzinger complex neurons
to reliance on the parafacial nucleus neurons
and box breathing just to give away
what’s probably already obvious
is you inhale, hold, exhale, hold, and repeat.
And that pattern of breathing,
even though it’s rhythmic in nature
because inhales precede exhales,
precede inhales and so on,
there’s a deliberate breath hold inserted there.
So anytime we’re taking conscious control of our breathing,
the parafacial nucleus is getting involved.
Now, you don’t have to assume
that the parafacial nucleus is the only way
in which we take conscious control of our breathing.
We can also take control of the pre-Butzinger complex.
You can do that right now.
So for instance, you are breathing
in some specific pattern now
that unless you’re speaking or eating,
no doubt is going to involve inhales followed by exhales.
But you could, for instance, decide that,
yes, inhales are active and exhales are passive,
but now you’re going to make the exhales active as well.
So rather than just inhale and then let your lungs deflate,
you could inhale and then force the air out.
That’s going to represent a conscious taking over of control
of the pre-Butzinger complex.
Okay, so the reason I’m giving this mechanistic detail
is A, it’s super important if you want to understand
all the tools related to breathing.
B, it’s actually a pretty simple system.
Even though the areas have fancy names
like pre-Butzinger or parafacial,
it’s pretty straightforward, right?
You have one area that controls rhythmic breathing,
inhale follows exhales.
And the other area which gets involved in breathing
anytime you start doubling up on inhales or exhales.
In fact, the parafacial nucleus
is the one that you’re relying on while you speak
in order to make sure that you still get enough oxygen.
It’s also the one that you will use
if you incorporate the physiological sigh or box breathing.
And frankly, most of the time
you’re using both of these circuits or these brain systems,
parafacial and pre-Butzinger in parallel.
Again, biology loves parallel systems,
especially for things that are so critical
that if we didn’t do them, we would die like breathing.
And so it makes sense that we have
two different brain structures that control this.
So now you have an understanding
of the mechanical control of breathing.
That is the different parts within the parts list
that are involved in breathing,
everything from nose to mouth, to alveoli, the lungs,
et cetera, and the muscles involved in moving the lungs.
You understand, I like to think a bit about
bringing oxygen in and removing carbon dioxide,
but not so much carbon dioxide
that you can’t actually use the oxygen that you have.
And you know about two brain centers,
one controlling rhythmic breathing
and one that controls non-rhythmic breathing.
I want to repeat something
that I said a little bit earlier as well,
which is that breathing is incredible
because it represents the interface
between conscious and subconscious control
over your not just body, not just your lungs,
but that how you breathe influences your brain state.
So by using your brain consciously to control your breathing
you are using your brain to control your brain.
The best way I’ve ever heard this described
was from a beautiful, I should say now classic paper
in the Journal of Physiology published in 1988
from Balistrino and Somjian
where the final line of their summary intro states,
the brain by regulating breathing
controls its own excitability.
And just to remind those of you
that don’t remember what excitability is,
excitability is the threshold at which a given neuron,
nerve cell can be active or not.
So when we breathe a certain way,
the neurons of our brain are more likely to get engaged.
They’re more likely to be active.
And when we breathe in other ways,
our brain becomes harder to activate.
Its excitability is reduced.
Now you might think excitability is a great thing.
You always want your brain to be excitable,
but that’s actually not the case.
And in fact, that very statement
that Balistrino and Somjian made
led to a number of other investigations
that were really important in defining
how if people over-breathe,
that is if they hyperventilate at rest,
they expel, that is they exhale too much carbon dioxide.
What that classic paper by Balistrino and Somjian led to
was a number of different investigations in humans
looking at how different patterns of breathing
impact the overall state of the brain
and the ability of the brain to respond to certain
what are called sensory stimuli.
Keep in mind that your brain is always active.
The neurons are firing at low level, low level, low level.
But when you see something or hear something,
or you want to focus on something,
or you want to exercise or really listen to something
or learn, certain circuits in your brain
need to be more active than everything else.
That is there needs to be really high
what’s called signal to noise.
There’s always a lot of noise and chatter in the background,
just like the chatter at a cocktail party
or at a stadium event.
In order to really pay attention, focus, learn,
all the incredible things that the brain can do,
you need that signal to get above the noise.
There’s a beautiful paper that asks,
how does the pattern of breathing,
in particular, how does over-breathing
change the patterns of activity in the brain?
This is a paper entitled
Effects of Voluntary Hyperventilation
on Cortical Sensory Responses.
And I will provide a link to the study
in the show note captions.
It’s a somewhat complicated paper.
If you look at all the detailed analyses,
however, the takeaway from this paper is exquisitely simple.
And I also believe incredibly important.
Basically what it showed is that when people hyperventilate,
they expel, that is they exhale more carbon dioxide
than they would normally.
So they become what’s called hypocapnic, okay?
Carbon dioxide levels are low in the blood.
And over a short period of time,
they become low in the tissues of the body.
When that carbon dioxide level drops low,
you would say, okay, well,
you’re still bringing in a lot of oxygen
because these people are hyperventilating,
so they should feel really alert.
And indeed, that’s what happens.
The people feel very alert.
However, because they’re not bringing
enough carbon dioxide in,
or rather the proper way to say it would be
because they’re over-breathing, exhaling too much,
they are not retaining or keeping in enough carbon dioxide.
Well, then that lack of carbon dioxide means
that the oxygen that they are breathing in
can’t be liberated from the hemoglobin,
can’t get to the brain.
And what they observe is about a 30 to 40% reduction
in the amount of oxygen that’s being delivered to the brain.
And the reduction in carbon dioxide
also prevents some of the normal patterns of vasodilation,
the dilating, the opening up of the capillaries.
So again, less blood flow, but most importantly,
as it’s shown in this paper,
the brain overall becomes hyper excitable.
It’s as if it’s being starved of oxygen and blood flow,
and all the neurons in a very nonspecific way
start increasing their firing levels.
So the background activity is getting louder and louder.
It’s like the rumbler, the noise of a crowd at a stadium.
And as a consequence, the sensory input from a sound
or from a touch or from some other event in the world
doesn’t get above the noise.
What this means is that when we hyperventilate,
because we aren’t retaining enough carbon dioxide,
we are not getting enough oxygen
to the tissues that need oxygen.
And as a consequence of that,
the brain becomes hyper excitable.
We actually know that there’s an increase in anxiety,
and we become less good,
less efficient at detecting things in our environment.
So we’re not processing information as well at all.
The noise goes up and the signal goes down.
Again, incredibly important set of findings.
I should also mention that hyperventilation is one way
that in the laboratory anyway,
or in neurosurgery units for some time,
physicians would evoke seizure in seizure-prone patients.
The reason that works is exactly the explanation
I just gave you.
Seizure is a hyper excitability of the brain,
not enough inhibition or suppression
of the overall circuitry.
So you get these waves or these storms
of electrical activity.
Low levels of carbon dioxide in the brain,
because of low levels of carbon dioxide in the blood,
are one of the major triggers for seizures.
Now, I realize that most people listening to this
are not epileptic, but nonetheless,
this brings us all back to this question
of what is normal healthy breathing?
As I mentioned before,
normal healthy breathing is breathing
about six liters of air per minute.
But of course, most of us don’t think
in terms of liters of air,
and we’re not gonna go measure our lung capacity,
at least most of us aren’t gonna do that.
Basically, if you are taking relatively shallow breaths
and you’re just sitting there working
or maybe even walking slowly,
again, not talking or engaging
in any kind of speech or eating,
chances are six liters of air per minute
is about 12 shallow-ish breaths.
And when I say shallow, I don’t mean, you know,
breathing like a little bunny rabbit or something like that.
I just mean, you know, casually breathing in, out, in, out.
The studies that have explored the breathing patterns
in large populations of individuals
who are not suffering necessarily
from any one specific ailment
have shown that most people breathe far too much per minute,
that they’re engaging in anywhere from 15 to 20
or even 30 shallow breaths per minute.
So they are vastly over-breathing
relative to how they should be breathing.
Now, of course, if you breathe more deeply,
so you take a vigorous inhale,
and then you expel that air,
well then, to get six liters of air
into your system per minute,
you’re probably only going to need
somewhere between four and six breaths
in order to get that six liters per minute.
Now, the total time that it takes
to do that inhale and exhale isn’t that much longer
than a kind of shallow breath,
provided you’re not deliberately breathing quickly
during those shallow breaths.
So then you say, well,
how is it that normal healthy breathing
that delivers the appropriate amount of carbon dioxide
into the system and doesn’t expel,
doesn’t exhale too much carbon dioxide?
You know, how are we supposed to do that normal breathing?
Right, are you supposed to breathe four times
and then hold your breath until the minute passes?
No, what you find is that the correct pattern of breathing
is going to involve two things.
First of all, nasal breathing,
because of the resistance it provides through the nose
that we talked about earlier,
is going to deliver more oxygen into your system.
You’re going to be able to generate more air pressure
to fill your lungs.
That greater air pressure
is going to take longer to exhale.
So already we’re increasing the amount of time
that each breath is going to take.
And also what you find is that people that are breathing
in the proper healthy manner,
that is that are balancing oxygen and carbon dioxide
in the proper ways,
are also taking pauses between breaths.
This is extremely important
because even though we have a brain center,
the pre-Botzinger complex that can control,
or I should say does control inhale,
exhale, rhythmic breathing,
those pauses between breaths are not always present.
In fact, often are not present
from people’s baseline breathing patterns.
And as a consequence, they over-breathe.
And as I told you before, when people over-breathe,
their brain becomes hyper excitable
at the level of the background noise,
and yet they are less efficient
at detecting and learning information.
And we’ll get into the specific studies
that really illustrate the learning aspect a bit later,
but they are less efficient at detecting
and learning information at focusing and so on
as a consequence of this over-breathing
and the hyper excitability that causes.
Now, of course, that’s also just emphasizing
the effects of over-breathing
and lack of carbon dioxide on the brain.
There are hundreds, if not thousands of studies
showing that when we don’t have enough carbon dioxide
in the tissues of our body,
that’s also problematic for all the tissues,
the liver, the lungs themselves, the stomach, et cetera,
that relate largely to shifts in pH
because of the fact that carbon dioxide
strongly regulates the acidity, alkalinity of the blood
and the tissues that that blood supplies nutrients to,
including carbon dioxide.
So the basic takeaway here is
you want to breathe in a healthy manner at rest.
And the best way to do that is to spend some time,
and it doesn’t take much,
maybe a minute or so each day,
paying attention to how quickly you are breathing per minute
when you are simply at rest,
when you’re making coffee in the morning,
when you’re sitting down to read,
when you’re on social media.
Chronically holding your breath isn’t good,
but neither is over-breathing.
And again, every study that has examined
the typical patterns of breathing
and patterns of breathing that show up as normal
and abnormal has found that more often than not,
during the nighttime, people are under-breathing,
and in the daytime, they are over-breathing,
they’re hyperventilating.
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So next, I’d like to address what you can do
about your normal patterns of breathing.
That is, how you or anyone can adjust
their normal patterns of breathing
from an unhealthy to an unhealthy state.
But the first thing we have to do, of course,
is determine whether or not you’re already breathing
in an unhealthy or in a healthy way.
And again, when I say healthy or unhealthy,
I mean, are you over-breathing?
Are you under-breathing?
Are you delivering the appropriate ratios
of oxygen and carbon dioxide
to the tissues of your brain and body?
In order to do this, we’re going to do a simple test.
Again, please don’t do this while driving
or operating heavy machinery or near water of any kind.
But assuming that you’re not doing any of those things,
I encourage you to sit down,
certainly not lie down, but just sit down.
I suppose you also could do it standing.
And we are going to do what’s called
the carbon dioxide tolerance test.
The carbon dioxide tolerance test
is a sort of back-of-the-envelope measure
of how well you are managing carbon dioxide.
That is, how well you can control your breathing
at both the mechanical and the chemical level.
It’s a very simple test.
What you’re going to do is,
for the next 10 seconds or so while I’m speaking,
you’re just going to breathe normally.
Now, again and again throughout this episode,
I’m going to encourage you
to be a nasal breather whenever possible.
But of course, there are instances
in which you want to engage mouth breathing.
But for the time being, as I continue to blab on
for the next few seconds, just inhale through your nose,
exhale through your nose.
You don’t have to deliberately slow your breathing
or increase the cadence of your breathing.
However, in that time, you’re also going to want to find
some sort of time-measuring device,
like it could be your phone or it could be a stopwatch.
What I’m going to ask you to do in a few minutes
is I’m going to ask you to inhale through your nose
as deeply as you possibly can.
That is, you’re going to fill your lungs
as much as you can through your nose,
and then start a timer and measure how long it takes
for you to deliberately control that exhale
until your lungs are empty, okay?
So this is going to be a controlled exhale through the nose
after a big, deep breath.
But for the time being,
keep breathing at a kind of calm, regular cadence, okay?
So you can find that time-measuring device now,
or you can come back to it later if you like.
When I say inhale, you’re going to inhale as deeply
as you can through your nose,
remembering that the diaphragm can really help you here
to get a deep inhale by having your belly move out
while you inhale.
And then when I say start,
you’re going to measure the time that it takes
to do a complete lungs-empty exhale.
In fact, I’ll measure it for you.
This will be one of the rare instances in this podcast
where there’s going to be a long period of silence
as I measure something.
So I’ve got a stopwatch here.
So please prepare to do the big inhale
and start inhaling now.
So inhale as deeply as you can through your nose,
fill your lungs as much as you can, okay?
Now, start, meaning slowly control the exhale
through your nose.
You’re trying to let that air out as slowly as possible.
And I’m just going to call out every 10 or 15 seconds or so.
And you want to note when your lungs are empty.
I know you can hold your breath with your lungs empty.
That is not an accurate measure, 15 seconds.
It is important that you know when your lungs are empty
and that you’re trying to control the exhale
as much as possible so that you don’t arrive
at that lungs-empty time too quickly.
I’ll explain what too quickly means, 30 seconds, okay?
For those of you that have already reached lungs-empty,
please go back to breathing normally.
For those of you that haven’t,
you can hang in here a little longer.
If you’re still discarding that air, 45 seconds.
And we’re rounding toward a minute, not quite there.
Some of you are probably still letting out that air.
I want to point out none of this has to do
with cardiovascular fitness level,
at least not in any kind of direct way.
And 60 seconds.
And I realize there will be a small subset of you out there
that are still exhaling your air in a slow lungs,
slow exhale manner through the nose.
Okay, so what we just did is a back of the envelope
carbon dioxide discard rate, okay?
If you need to pause this and go back and try it again,
you just want to time how long it takes you
to go from lungs full to lungs empty.
Again, with the full understanding,
I know that you can all sit there like beasts
and hold your breath with your lungs empty,
but please don’t do that because that’s not going
to be informative for what I’m telling you now.
What I’m going to tell you now is that if it took you
20 seconds or less to expel all your air,
that is you couldn’t extend that exhale
longer than 20 seconds,
in a kind of back of the envelope way,
we can say that you have a relatively brief
or low carbon dioxide tolerance, okay?
If it took you somewhere between 25 and 40,
maybe 45 seconds to expel all your air,
that is you could control that exhale
for about 45 seconds or 30 seconds,
then you have a moderate level of carbon dioxide tolerance.
And if for instance, you were able to go 50 seconds
or longer for that discard until you hit lungs empty,
you have a fairly high degree of carbon dioxide tolerance.
Now, here’s the deal.
If you had low carbon dioxide tolerance,
that is your 20 seconds or less,
you’re going to write down the number three, okay?
If you had moderate levels of carbon dioxide tolerance,
you’re going to write down the number five
or you could even put five to six.
And then if you are in that bracket of people
that was able to discard your air over a period
of 50 seconds or more,
you’re going to write down the number eight to 10, okay?
Now, what are these numbers?
What are we talking about?
And before we get into what to do with these numbers,
I want to emphasize again,
this does not have to do with fitness level per se.
I know some world-class triathletes
that have very fast carbon dioxide blow off times.
That is their discard rates are 20 seconds or less.
I should also point out that if you’re very stressed,
that number is going to be very small.
If you’re very relaxed,
like you just woke up after a long night of sleep
and you feel great,
that number is going to be extended, okay?
So this is a back of the envelope measure
that you’re going to use each time you decide
to do the exercise I’m going to tell you about in a moment.
And the exercise I’m going to tell you about in a moment
can be done every day if you like.
But what the most interesting studies,
at least to me,
indicate is that you could do the exercise
I’ll tell you about even just once or twice a week
and greatly improve your efficiency of breathing
and shift yourself away from over-breathing when at rest,
even if you’re not thinking
about how you’re breathing at rest.
Okay, so what is this exercise?
Well, you just got your number,
either low, medium, or high bracket number
for carbon dioxide discard rate.
Remember, if you’re in the low category,
your number is three.
If you’re medium, it’s five to six.
And if you are in the long carbon dioxide discard rate,
long duration carbon dioxide discard rate,
that is eight to 10 is your number.
Now you’re going to do two minutes
of what most people would call box breathing.
What is box breathing?
Box breathing are equal duration, inhale, hold,
exhale, hold, repeat.
So inhale, hold, exhale, hold.
Sounds very easy, right?
How long do you inhale and then hold,
exhale, and then hold?
Well, you now know.
If you were in the low group of carbon dioxide discard rate,
your inhale is going to be three seconds,
your hold will be three seconds,
your exhale will be three seconds,
and then you repeat three seconds.
So each sides of the box, if you will,
is going to be three seconds long.
If you were in the moderate carbon dioxide
discard rate category,
then you’re going to inhale for five to six seconds,
hold for five to six, exhale for five to six,
hold for five to six, repeat for about two minutes.
You could do three minutes if you want,
but I think it’s important to have protocols
that are feasible for most people.
And that’s going to mean doing things
for about two to five minutes
when it comes to these breath rehabilitation exercises
for restoring normal breathing.
And then of course, if you were in the long category
of carbon dioxide discard rate,
you should be able to do an eight to 10 second inhale,
eight to 10 second hold, eight to 10 second exhale,
eight to 10 second hold, and repeat, okay?
So you could do that exercise now if you like,
or you could do it at some point offline.
You can pause this podcast if you want and go try it.
That’s an exercise that you can do
for about two to three minutes, once or twice per week.
What’s happening when you do that exercise?
Well, first of all, you are greatly increasing
your neural mechanical control over the diaphragm.
This is very important.
Most people are not aware of this phrenic nerve pathway
in the diaphragm, and you’re greatly increasing
your mechanical control over this pathway
through the process we call neuroplasticity.
When you deliberately focus on a aspect
of your nervous system control,
in particular nervous system control over musculature
that normally is subconscious
and you’re not paying attention to,
when you actively take control of that,
it requires that your brain adjust and rewire
the relationship between the different components
of that circuit.
And the wonderful thing is that has been shown
to lead to changes in your resting pattern of breathing.
Now, why did we go through the whole business
of doing the carbon dioxide tolerance test?
Well, for people who don’t tolerate carbon dioxide
very well, they don’t have very good phrenic,
that is neuromechanical control of the diaphragm,
for whatever reason.
Again, it doesn’t mean you’re not fit.
It just means you don’t have,
or you have not yet developed
neuromechanical control of the diaphragm.
It would be near impossible for you to do box breathing
for two or three minutes with eight seconds in,
eight seconds hold, eight seconds exhale, eight second hold.
So that’s why we do a test
to see what you’re capable of doing.
You don’t want the box breathing to be too strained
where you’re really challenged to get around the whole box.
You want it to be relatively easy
because remember you’re trying to translate this pattern
to your normal pattern of breathing.
That is your pattern of breathing
when you’re not consciously thinking about breathing.
And what are we really translating
when we do this box breathing type exercise?
What you’re translating is the ability
to pause between breaths and yet take full,
mechanically driven breaths
that involve the phrenic nerve and diaphragm.
So again, you’re encouraging,
especially if you use nasal breathing
when you do the box breathing,
you’re encouraging phrenic control over the diaphragm
and you’re getting that six liters of air per minute or so
using fewer and fewer breaths over time.
So this is a, again, zero cost,
although it does cost a little bit of time,
zero cost approach to adjusting your normal pattern
of breathing at rest,
which has a huge number of positive outcomes
in terms of your ability to stay relatively calm,
to not get the hyperexcitability of the brain.
It has actually been shown in various studies,
and we’ll talk about one in particular later,
to greatly improve not just levels of calm
and reduce bouts of stress,
but also improve nighttime sleep.
There are a huge number of benefits
that can come from doing this box breathing exercise,
but you got to get the duration
of the sides of the box right,
and that’s why you do the carbon dioxide tolerance test.
One thing that many people notice
after doing the carbon dioxide tolerance test,
even just once,
and then doing this box breathing exercise
once or twice a week,
is that after two or three weeks,
the box breathing itself becomes very easy.
And in that case,
I recommend taking the carbon dioxide tolerance test
over again,
and almost always what you’ll find
is that you have been able to extend
your carbon dioxide discard rate,
and therefore you now fall into a different category,
not just the lower medium,
but the long carbon dioxide discard rate category,
and you are able to extend the duration
of those inhale hold, exhale holds
during the box breathing.
And of course,
the ultimate benefit of all this
is that it translates to deeper
and yet less frequent breathing
when at rest and when not consciously paying attention
to how you’re breathing during the daytime.
Again, if at all possible,
do all of this breathing through the nose.
For those of you that have a severely occluded nose,
the recommendation always is to breathe
through your nose more,
but I do realize that for some people,
it’s really uncomfortable to breathe through the nose
because they have such an occluded nasal pathway.
And for you folks,
doing some of this breathing through the mouth
can probably suffice,
but if at all possible,
do the breathing through the nose.
And please also let me know how your progress
evolves over time with the carbon dioxide discard rate
and the box breathing.
And of course,
the positive shifts that occur
in normal unconscious daytime breathing
translate to all the opposite things
that we talked about when you are over breathing
during the daytime.
So what I just described
in terms of the carbon dioxide tolerance test
and the exercise using box breathing
to restore normal patterns of breathing
and not over breathe
and therefore not eliminate too much carbon dioxide
is exactly the two tests
that were incorporated into a study
that my laboratory did in collaboration
with our associate chair of psychiatry
at Stanford School of Medicine, Dr. David Spiegel,
who’s also been a guest on this podcast previously.
And that study explored box breathing,
but it also explored other forms of breathing
and actually compared those forms of deliberate breathing
to meditation as a means to explore
what are going to be the minimal effective doses
and most effective ways
to chronically reduce stress around the clock
and improve mood and improve sleep.
So the study I’m referring to was just published recently.
It’s entitled,
Brief Structured Respiration Practices,
Enhance Mood and Reduce Physiological Arousal.
We will also provide a link to this paper
in the show note captions.
What this study really focused on was a simple question,
which is what is the shortest and most effective practice
that people can use in order to reduce their levels
of stress, not just during that breath work practice
or meditation practice, but around the clock,
24 hours a day, including improvements in sleep.
And we were excited to do this study
because many studies had explored how meditation
or in some cases, fewer studies had explored
how breath work can impact different brain states
or bodily states.
But very few studies had explored how those breath work
or meditation practices influenced body brain states
around the clock when people were not performing
the particular meditation or breath work practice.
The reason we were able to do this study
was really fortunate.
The folks over at WHOOP were generous enough
to donate a bunch of WHOOP straps,
which allowed us to measure heart rate variability,
a number of other different physiological parameters.
We also got subjective reports about people’s mood
and feelings of wellbeing.
We got data about their sleep pinged to us
from remote locations.
So these people, rather than being brought
to the laboratory and being in a very artificial
circumstance, the laboratory, as much as we like to think
our laboratory is realistic, we have virtual reality
and things like that.
There’s nothing as realistic as the real world.
And so we were able to have more than 100 subjects
out in the real world, living their real lives,
pinging back to us data all the time, 24 hours a day,
so that we could measure how their different interventions
that we asked them to do, breath work practices
or meditation practices were impacting physiological
parameters and they were also informing us regularly
about their subjective mood, et cetera.
We got a lot of data, as you can imagine.
And the basic takeaway from the study was twofold.
First of all, we discovered that deliberate breath work
practices done for about five minutes per day
across the course of about a month,
led to greater reductions in stress
than did a five minute a day meditation practice.
Now, that is not to say that meditation is not useful.
In fact, there are dozens, if not hundreds of papers,
including one particular, I should say,
particularly beautiful study from Wendy Suzuki’s lab
at New York University showing that a daily 10 to 13 minute
mindfulness meditation practice can greatly improve focus,
memory, and a number of other things related to cognition
and learning.
However, the research on meditation has shown us
that meditation, at least short meditations,
mainly lead to improvements in focus and memory,
not so much reductions in stress,
although they do lead to reductions in stress.
What we found was that any number of different breath work
practices, and we explored three,
done for five minutes a day,
outperformed meditation in terms of the ability of breath
work to reduce stress around the clock
compared to meditation.
The three types of breath work that we explored
also showed different effects.
I should mention the three types of breath work
that we compared were box breathing of the sort
that you just learned about.
We compared that to something called cyclic sighing,
which involves two inhales through the nose
to get maximally inflated lungs,
followed by a long exhale.
I’ll return to that in a moment.
That was repeated for five minutes at a time
for each session.
And a third breath work practice,
which was cyclic hyperventilation,
which as the name suggests,
involves people inhaling deeply through the nose,
then exhaling passively through the mouth,
and then repeating inhale through the nose,
exhale through the mouth,
repeating that for 25 cycles,
one cycle being an inhale and an exhale.
So that equals one cycle,
repeating that for 25 cycles,
then exhaling all their air and holding their breath
with lungs empty for about 15 to 30 seconds,
and then repeating inhale, exhale,
cyclic hyperventilation for the duration of five minutes.
Okay, so people were divided into these different groups,
either mindfulness meditation where they sat,
they were not told to control their breathing
in any specific way, they closed their eyes,
their focus, their attention on a region
just behind their forehead, one group did that,
the other group did cyclic sighing,
another group did box breathing,
another group did cyclic hyperventilation.
As any sort of clinical trial like this ought to,
we then swapped people into different groups
so they served as their own control,
so we could evaluate any between
and within individual variability.
Again, there are a lot of data in this paper,
but the takeaway was that for the sake of stress reduction
around the clock, and for the sake of improving sleep
and mood, the most effective practice
of the four practices that we examined
was the cyclic sighing.
Again, cyclic sighing is performed the following way,
you inhale through the nose as deeply as you can,
then you do a second inhale immediately afterwards
to try and maximally inflate the lungs,
in fact, that’s what happens,
we know that during that second inhale,
even if it’s just a very sharp, short inhale,
the extra physical vigor that’s required
to generate that second inhale
causes those avioli of the lungs, which may have collapsed,
and indeed in between breaths,
and often even just through the course of the day,
and especially if we get stressed,
those avioli of the lungs start to collapse,
and because they’re damp on the inside,
they have a little bit of fluid,
they’re like a balloon with a little bit of fluid
in the middle, it takes a little bit of physical force
to pop those open, now you’re not literally exploding
them pop, but you’re reinflating them with air,
and then you perform the long exhale through the mouth
until lungs are empty, so it looks exactly like this.
Now, we know that one single physiological sigh
of the sort that I just described,
performed at any time of day, under any conditions,
whether or not you’re about to walk on stage to give a talk,
or you’re in a meeting and you’re feeling stressed,
or you’re in a conversation that’s very stressful,
or you can feel stress mounting because you’re in traffic,
or any number of psychological or physical stressors
that may be approaching you or you feel are oppressing you,
doing one physiological sigh of the sort
that I just described is the fastest physiologically
verified way that we are aware of to reduce your levels
of stress and to reintroduce calm,
that is to shift your autonomic nervous system
from a state of heightened levels of autonomic arousal,
that is sympathetic nervous system, as it’s called,
is at a higher activation level
than the so-called parasympathetic nervous system.
Again, sympathetic nervous system,
having nothing to do with sympathy,
has everything to do with so-called fight or flight,
although it controls other things too,
including positive arousal.
And the parasympathetic nervous system,
often referred to as the rest and digest system,
although it does other things too,
is associated with calming.
Those two things are always in kind of push-pull
with one another, like a seesaw or push-pull,
however you want to think about it.
One physiological sigh, meaning that big deep inhale,
short second inhale, also through the nose,
and then long exhale to completely lungs empty,
is known to restore the level of balance
in the sympathetic parasympathetic neural circuitries,
and is the fastest way to reintroduce calm.
That’s one physiological sigh.
In this study, what we asked was that people perform
that repeatedly, so-called cyclic sighing,
for the duration of five minutes.
And the people who did that cyclic sighing
for five minutes a day,
regardless of the time of day that they did it,
experienced the greatest reductions in stress,
not just during the practice,
but around the 24-hour cycle.
And it translated, again,
to all sorts of positive subjective changes,
improvements in sleep.
Lower resting heart rate at all times of day.
So this is important.
Again, this study was not just exploring
what happens during meditation or breath work,
cyclic sighing, et cetera.
It was exploring how the changes that occur
during that practice translate to changes in breathing
and heart rate, mood, et cetera,
throughout the 24-hour cycle.
So the takeaway here is twofold.
First of all, if you’re somebody who wants
to improve your mood and reduce your overall levels
of stress, and you only have five minutes a day
to invest in that,
hopefully you’re doing all the other things
like trying to get proper sleep and exercise,
social connection, nutrition, et cetera,
sunlight in the morning, of course.
Can’t leave that out.
But if you were going to devote five minutes a day
to a stress reduction practice
that is now supported by data to translate
to reductions in stress around the clock,
the data say that you would want to invest that
in cyclic sighing, that is double inhale through the nose,
extended exhale through the mouth
until your lungs are empty,
then repeat for five minutes a day.
You, of course, if you like, could do meditation.
It still had positive effects, meaning it reduced stress,
although not as much as cyclic sighing.
You could do box breathing if you want
for the purpose of reducing stress.
All the practices we explored did reduce stress,
but cyclic sighing performed for five minutes a day
had the most robust and pervasive effect
in reducing stress, improving mood, and improving sleep.
That’s the first message of the study.
The second takeaway is that one physiological sigh,
that’s right, just one physiological sigh
where you inhale deeply through the nose,
another inhale through the nose
to maximally inflate the alveoli of the lungs,
and then you exhale to completely lungs empty,
and then go back to normal breathing
is the fastest way to introduce a level of calm
and to reduce your overall levels of stress in real time.
And this is very important.
I think that out there these days,
we hear a lot about stress reduction techniques,
and most all of the stress reduction techniques
that have been explored,
everything from massage to meditation to breath work
to a hot shower to a foot rub will calm you down.
The question is, do they calm you down
just during that practice?
Great if it does, but does it also translate
to reduce levels of stress at other times
in the 24-hour cycle and other positive effects as well?
So one physiological sigh is a very efficient way
to adjust that ratio of sympathetic
to parasympathetic activation
and immediately bring about calm.
So it’s excellent for real-time control of stress.
The other thing about physiological sighs
is that it’s not a hack.
It’s not the application of a breathing practice
to something that it wasn’t intended for.
In fact, physiological sighs were not discovered by me
at all.
They were discovered by physiologists in the 1930s
who found that when people under breathe,
they have a buildup of carbon dioxide in their system.
And even though carbon dioxide is essential for life,
you don’t want too much of it in your system.
And that people, whether or not they were asleep or awake,
would engage a physiological sigh spontaneously,
subconsciously.
They would do this double inhale through the nose
and extended exhale through the mouth.
And that did not just eliminate excessive carbon dioxide
from the system.
It also rebalanced the oxygen carbon dioxide ratio
in the proper ways.
In fact, it’s observed in animals.
You might see this in animals that are tired.
When animals or humans get tired,
they tend to start under breathing a little bit.
And that can often disrupt the balance
of carbon dioxide and oxygen.
And right before a dog will go down for a nap,
for instance, you’ll notice
that it’ll do this double inhale exhale.
People, when they are sleeping,
if they hold their breath for a period of time,
which frankly all of us do periodically throughout sleep,
they will engage a spontaneous physiological sigh.
During the daytime, we are often holding our breath,
especially nowadays.
And there’s a study on this
that we’ll talk about a little bit later
where when people text message or they’re emailing,
although nowadays people are mainly on social media
and text messaging, they often are holding their breath.
They will follow a breath hold by a physiological sigh
because during that breath hold,
they’re building up the level of carbon dioxide
in their system.
Now, mind you, I spent close to a half an hour telling you
that most people are over-breathing at rest.
And that’s also true.
But people often will shift from over-breathing
to under-breathing, which is a terrible pattern.
So physiological sighs done either as a one-off,
one physiological sigh to clamp stress
or reduce stress in real time,
or repeatedly over five minutes
as a practice that you do each day
is going to be not just the most effective way
to approach reducing stress around the clock
and in real time,
but also the one that’s highly compatible
with the way that the neural circuits
that control breathing were designed.
The physiological sigh
has some other very useful applications.
One of the more, I would say useful ones,
at least to those of you that exercise
is going to be the use of physiological sigh
in order to remove the so-called side stitch.
So if you’ve ever been running or swimming or exercising,
you felt a cramp on your right side,
chances are, despite what your high school PE coach told you
that raising your arms above your head
or drinking less water before you exercise
is not going to get rid of that cramp.
And here’s why, it’s not a cramp at all.
If you recall the cervical three, four, and five nerves
that give rise to the phrenic nerve
and go down and innervate your diaphragm,
well, as I mentioned before,
a certain number of those nerve fibers
actually course into the diaphragm and go up underneath.
And if you recall earlier,
I also said that the diaphragm
sits right on top of the liver.
In other words, you actually have a sensory innervation
of the diaphragm, the deep diaphragm,
and the liver.
And there’s something called referenced pain,
which is what people generally experience
when they have that side stitch on their right-hand side.
So if you’re ever exercising
and you feel a cramp on your right-hand side,
it’s possible that it’s a genuine cramp,
but more likely is the fact
that that phrenic nerve sensory innervation
is now being carried up to your brain
and you are detecting some local or referenced pain
in the liver and in the diaphragm.
Now that doesn’t necessarily mean
you’re doing anything wrong,
although you might not be breathing properly
for running at that moment.
And that’s what gave rise to it.
It could be some spasming of the phrenic nerve
or some inefficient breathing during running.
We had an entire series on fitness with Dr. Andy Galpin.
One of those episodes
included a lot of information on breathing.
It was the episode on endurance,
although breathing was a topic
that was thread through multiple episodes in that series.
You can find that series at hubermanlab.com.
It talks a lot about how to breathe during running,
how to breathe during weightlifting, et cetera.
But the point for now is that
if ever you’re experiencing that right side side stitch,
I encourage you to perform the physiological sigh.
And the good news is you can perform it
while still running or while still swimming.
Although I suppose with swimming,
you might have to make some adjustments
because of course you don’t want to inhale water
or while cycling or any type of activity.
If you’d perform that physiological sigh,
generally two or three times,
what will occur is that because of changes
in the firing of the phrenic nerve,
and in particular because of changes in the sensory feedback
from the sensory component of the phrenic nerve
back to the brain,
you will experience an alleviation of the pain
from that right side side stitch.
In other words, you can get rid of side cramps
doing physiological sighs during activities,
in particular during running activities.
Now, I should also mention that if you’re experiencing
a side stitch on the left side,
chances are that has to do with excessive air
or fluid in your stomach.
And there are reasons for that
that also have to do with the way that the phrenic nerve
is it’s bilateral and branches to both sides
and is catching sensory input on the left side
from some of the local organs
and sensory innervation of those organs.
But if you have right side side stitch,
the physiological sigh done two or three times
while still running ought to relieve that side stitch.
Now, as long as we’re talking about breathing
and the phrenic nerve and the relationship
between the phrenic nerve and your liver and your stomach
and some of the other organs in that neighborhood,
we should talk about the relationship
between breathing and heart rate.
This is an incredibly important topic,
so much so that I perhaps should have brought it up
at the beginning of the episode,
but nonetheless, you now know what your diaphragm does,
right?
When you inhale, your diaphragm moves down.
That’s right.
When you contract your diaphragm, it moves down.
It creates space for your lungs to inhale.
And when you exhale, your diaphragm moves up.
Well, when you inhale and your diaphragm moves down,
what happens is there’s more space created
in the thoracic cavity,
in particular, if you’re also breathing deeply
and you’re using those intracostal muscles
to expand your ribs.
As a consequence, the heart actually gets
a little bit bigger.
It’s a temporary enlargement in the heart,
but it’s a real enlargement.
And as a consequence, whatever blood is in the heart
is now in a larger volume because the heart got bigger.
And as a consequence, that blood is moving more slowly
through that larger volume for a short period of time,
but nonetheless, it’s moving more slowly.
Your nervous system detects that
and sends a neural signal to the heart
to speed the heart rate up.
In other words, inhales increase heart rate.
The opposite is true when you exhale.
When you exhale, your diaphragm moves up.
Your rib cage tends to move inward a bit
and you compact the heart.
You reduce the volume of the heart overall.
When you reduce the volume of the heart overall,
blood flow through the heart accelerates
because it’s a smaller volume.
So given unit of blood is going to move more quickly
through that small volume.
Your nervous system detects that
and sends a signal to slow the heart down.
So just as inhales speed the heart up,
exhales slow your heart rate down.
Now, of course, even though you can double up on inhales
or even triple up on inhales,
sooner or later, if you inhale,
you’re going to have to exhale, all right?
And the converse is also true, of course.
So what does this mean in terms
of controlling your heart rate?
Well, let’s say you are going in for a blood draw
or you’re going out on stage and you’re stressed.
Well, I would encourage you to do a physiological side,
maybe two physiological sides to bring your level of calm up
and your level of stress down.
Nonetheless, if you have any reason
why you want to quickly reduce your heart rate
or accelerate your heart rate
for sake of physical work output
or to calm yourself down additionally,
not just use the physiological side,
well, then you can take advantage of this relationship
between inhales and exhales controlling heart rate.
If you want to increase your heart rate,
you can simply inhale longer and more vigorously
relative to your exhales.
And if you want to decrease your heart rate,
well, then you’re going to make your exhales longer
and or more vigorous than your inhales.
In fact, this process,
which is called respiratory sinus arrhythmia
is the basis of what we call heart rate variability.
Heart rate variability involves the vagus nerve,
the 10th cranial nerve, which is a parasympathetic nerve
that is associated with a calming aspect
of the autonomic nervous system,
slowing your heart rate down by extending your exhales.
And it really forms the basis
of most all breathing practices.
If you look at any breathing practices,
whether or not it’s Wim Hof breathing, Tummo breathing,
Kundalini breathing, Pranayama breathing,
physiological sighing, cyclic sighing,
and on and on and on.
If you were to measure the ratio of inhales to exhales
and the vigor of inhales to exhales,
what you would find is that each one would create
a net increase or a net decrease in heart rate
that could be very accurately predicted
by whether or not that breathing practice
emphasized inhales, emphasized exhales,
or had those two features inhale and exhale
be of equal duration and intensity.
In fact, if you wanted to equilibrate your heart rate,
what you would do is you would do box breathing
because inhale, hold, exhale, hold is by definition
creating equal duration inhales and exhales
of essentially equivalent vigor.
When you do a physiological sigh,
you’re doing two big inhales,
which is gonna speed your heart rate up just a little bit,
but then a long extended exhale.
The exhale in the end is much longer
than the two inhales even when combined.
And so you get a net decrease in heart rate,
the calming effect.
And then practices such as TUMO breathing
or Wim Hof breathing or cyclic hyperventilation,
deep inhales and exhales,
the inhales are more vigorous
compared to the more passive exhales
are going to lead to increases in heart rate.
Okay, so the relationship between breathing and heart rate
is an absolutely lockstep one
where your heart rate follows your breathing,
your heart rate and your breathing
are in an intimate discussion with one another,
but where always and forever
your inhales increase your heart rate,
your exhales decrease it.
Now this feature,
which physicians call respiratory sinus arrhythmia,
or we sometimes hear about more often nowadays
as heart rate variability
is something that people in sport
have known about for a very long time.
It’s why, for instance,
that marksmen will exhale just prior to taking a shot.
That’s particularly true
for people that compete in the biathlon
where they cross country ski.
So their heart rate is up, up, up, up, up.
Then they’ll get to the point
where they actually have to shoot at a target
and then they’ll exhale
and then they’ll shoot at the target.
This is also why, for instance,
if you want to bring your heart rate down very quickly
between rounds of martial arts,
there are a number of different ways to do that,
but an extended exhale of any kind,
or frankly, any breathing practice that emphasizes exhales
is going to bring your heart rate down.
This has been incorporated
in a number of different contexts,
including sport, military.
It’s also now being incorporated in the clinical context
for people who feel a panic attack coming on.
I’m very gratified to learn that the physiological sigh
is now being explored as a tool
to prevent panic attacks and anxiety attacks.
This is prior to the panic attack,
people bringing their heart rate down again
through those extended exhales.
So learning to extend your exhale
is really a terrific skill to master,
and it’s a very easy skill to master, frankly.
Why do I say a skill?
Well, remember what I said earlier,
which is that humans inhale actively
and most typically will passively exhale,
just let the air drop out of them at whatever rate,
depending on how much air they inhaled.
Actively exhaling, that is actively relaxing the diaphragm
and actively relaxing those intercostal muscles
of the chest, those ones, or I should say between the ribs,
is a skill that you can very quickly acquire
and will allow you to use that relationship
between the phrenic nerve, the diaphragm,
the size of the heart, the heart volume, and all that stuff
to really take control of heart rate quickly
so that if you feel like your heart is racing too much,
and frankly, a lot of people have a lot of
what’s called interoceptive awareness,
especially anxious people,
they can really sense what’s going on in their body,
other people less so, like, oh my God, my heart’s beating,
it’s like ready to jump out of my chest,
and I don’t like that, I don’t like that.
Big, long exhale.
Doesn’t matter if you do it through the nose or the mouth,
big, long exhale is going to allow you
to slow your heart rate down.
Let’s talk about hiccups.
Everybody experiences hiccups from time to time.
I think most people would agree that one hiccup,
sort of funny, two hiccups in a row is really funny,
and three hiccups in a row
is where it starts to be concerning,
in part because hiccups can be kind of painful,
you can experience pain in your gut or your lower abdomen,
and sometimes in your chest as well,
and it feels kind of intrusive,
it gets in the way of having conversation
or just sitting there and relaxing.
Fortunately, there’s a simple way to get rid of hiccups,
and you can arrive at that simple technique
if you understand a little bit about
what gives rise to hiccups.
The reason we get hiccups at all
is because we experience a spasm of the phrenic nerve.
The phrenic nerve, as you recall,
is a nerve that emanates from the cervical region,
to be specific, C3, 4, and 5,
those spinal nerves go down, of course, behind the heart,
and innervate the diaphragm, which is the muscle,
that when it contracts, it moves down,
allows the lungs to fill,
and then when you relax the diaphragm,
then the diaphragm moves up and the lungs shrink
or they expel air, so-called exhalation.
Now, the phrenic nerve also has that sensory branch,
so it’s not just involved in controlling the diaphragm
at the motor level,
it’s also sensing things deep within the diaphragm
and in the liver as well,
because the liver sits right below the diaphragm.
So a hiccup has that painful sensation from time to time,
because there’s a rapid sensory feedback,
or a signal rather,
of a sharp kind of sensation of contraction
within the diaphragm,
and that’s relayed back to the brain
and you consciously perceive that as a little bit of pain,
and then, of course, the hiccup is the hiccup,
which is the spasming of the phrenic nerve
that you experience more or less in your throat,
but all this really is happening along the phrenic nerve
and toward the diaphragm.
What this all means is that if you can stop the phrenic nerve
from spasming, you can stop hiccups.
There are a lot of approaches that people have tried to take
to eliminate spasming of the phrenic nerve.
You’ll hear that breathing into a bag,
which is one way to re-ingest or re-inhale carbon dioxide
that otherwise would be expelled out
into the environment can help.
That’s a very indirect method.
It rarely works, frankly,
because it really has to do more with adjusting
your breathing to try and adjust the activity
of the phrenic nerve.
It’s a really roundabout way of trying to alleviate hiccups.
Some people will experience relief from drinking
from a glass of water from the opposite side of the glass,
so you sort of have to tilt over at the waist.
It’s a kind of messy approach.
Again, it doesn’t tend to work a lot of the time.
For some people, it works every time,
but for most people, it doesn’t work at all.
However, there is a technique
that can reliably eliminate hiccups,
and it’s a technique that takes advantage
of hyper-contracting the phrenic nerve
over a short period of time
so that it then subsequently relaxes
or alleviates the spasming of the phrenic nerve.
And that simple method is to inhale three times in a row.
This is a very unusual pattern of breathing,
but what it involves is taking a big,
deep inhale through your nose.
Then before you exhale any air,
take a second inhale through the nose,
however brief that inhale might be,
and then a third, even micro or millisecond long,
inhale through your nose to get that third inhale,
and then hold your breath for about 15 to 20 seconds,
and then slowly exhale.
So even though I’m not experiencing any hiccups right now,
I will demonstrate the method for eliminating hiccups
so that you’re all clear on how to do it, okay?
Here I go.
Okay.
Okay, so it’s three inhales all through the nose,
and it is true that that second and third inhale
takes some physical effort to really get additional air
into the lungs without exhaling first.
It feels like the only way I can describe it really
is as a sharp second and third inhale,
because you really have to engage the musculature
of those intracostal muscles in the diaphragm
in order to do it.
And then that long exhale can be through the nose
or the mouth, but I find it particularly relaxing
or even pleasant to do it through the nose.
This method of three inhales through the nose
followed by a long exhale through the nose or mouth
will eliminate hiccups right away,
because what it does is it hyper excites the phrenic nerve
three times in a row, a very unnatural pattern
for the phrenic nerve to fire.
And then it undergoes a hyperpolarization, as we call it,
in which the phrenic nerve actually stands
a much lower probability of getting activated again
for some period of time afterwards.
So it is important that you try and return
to normal cadence of breathing
after doing this three inhales followed by the long exhale.
If you need to perform it a second time
in order to eliminate hiccups,
because they’re simply not going away, that’s fine.
You can do that.
But as far as we know, this is the most efficient
and science supported way to eliminate hiccups.
Now, up until now,
I’ve been talking about breathing techniques
and I’ve mainly focused on breathing techniques
that emphasize the exhale,
whether or not it’s the carbon dioxide tolerance test,
whether or not it’s cyclic sighing
or the physiological side that you use in real time
to reduce stress.
One thing that we haven’t talked about so much
is cyclic hyperventilation.
Cyclic hyperventilation, as you recall,
is a bout of 25 or so breaths,
inhaling deeply through the nose
and then passively exhaling,
or sometimes actively exhaling, typically through the mouth.
So it might look like this.
Ah, ah.
That’s a very active inhale through the nose
and exhale through the mouth.
It can also be done active inhale through the nose,
passive exhale through the mouth, like so.
Ah, ah.
In any event, that pattern of breathing
repeated for 10 to 25 breaths
greatly increases levels of autonomic arousal.
In fact, it’s known to deploy adrenaline from the adrenals.
And in our study, we had people then expel all their air,
so breathe out, hold their breath for 15 to 30 seconds,
and then repeat for a period of five minutes.
That did lead to some very interesting
and positive physiological changes
in terms of stress mitigation,
although not as significant as was observed
with cyclic sighing, as I talked about earlier.
Now, there is a lot of interest in cyclic hyperventilation
for sake of, for instance, extending breath holds.
This has become popular in part
because of the so-called Wim Hof method,
which is a method that combines breathing,
cyclic hyperventilation, followed by lungs full
or lungs empty breath holds,
depending on which variant of the Wim Hof method
one is using.
Separately, and I really want to emphasize separately,
the Wim Hof method also involves deliberate cold exposure,
which as all of you know, I’m a big fan of,
and we’ve done episodes of this podcast on,
and we have toolkits on deliberate cold exposure
for increasing dopamine levels, epinephrine levels,
immune system function, et cetera.
Wim Hof method also incorporates that,
and it has a mindfulness component.
I do want to caution people
that anytime you’re doing cyclic hyperventilation,
you want to be very cautious
about not doing it in or near water
because it does greatly increase the risk
of shallow water blackout.
And that’s because when you do cyclic hyperventilation,
you are expelling,
you’re exhaling more carbon dioxide than usual.
And what I haven’t told you yet
is that the trigger to breathe
is actually an increase in carbon dioxide.
What I mean by that is you have a small set of neurons
in your brainstem that can detect
when carbon dioxide levels in your bloodstream
reach a certain level.
And when they reach that level,
they trigger the gas reflex
and or the hunger for breathing.
In other words, we don’t breathe because we crave oxygen,
although we do need oxygen, of course,
in order to survive and for our brain to function
and our bodily organs to function.
But our brain is wired such that it has a threat sensor,
which is carbon dioxide levels are getting too high.
And that’s what triggers the motor reflex to breathe
and to, in some cases, gasp for air,
depending on how starved for air we are.
So if you do cyclic hyperventilation,
whether or not it’s Wim Hof method
or whether or not it’s TUMO method,
again, these things are similar.
They’re not exactly the same.
There are other breathing methods
that incorporate cyclic hyperventilation.
What you’re doing is you’re getting rid
of a lot of carbon dioxide.
And therefore you’re removing the impulse
or lowering the impulse to breathe
so that when you enter that breath hold phase
after the hyperventilation,
it’s a much longer period of time
before you feel the anxiety and the hunger
and the impulse to breathe.
That’s one of the real benefits of any technique
that incorporates cyclic hyperventilation
is that rather than reduce your stress level in real time,
it actually does the opposite.
It increases your stress level,
increases your level of autonomic arousal,
but you’re doing it deliberately.
And then during those breath holds,
what’s happening is you have a lot of adrenaline
circulating in your system
because of the way that hyperventilation
triggers the release of adrenaline from your adrenal glands.
It also triggers the release of epinephrine,
which is the same as adrenaline
from a little brain area called locus coeruleus,
which makes you feel more alert.
And then during those breath holds
and in the subsequent rounds of cyclic hyperventilation,
people experience what it is to have a lot of adrenaline
in their system,
but they are controlling the release of that adrenaline,
which is far and away different
than when life events are triggering that adrenaline.
So what it really is,
is a form of self-induced stress inoculation.
And I do think there are benefits
to practicing cyclic hyperventilation
because it does allow you to learn how to self-deploy
adrenaline and epinephrine from locus coeruleus
and from the adrenals, right?
Got that backwards.
Adrenaline from your adrenals
and epinephrine from locus coeruleus.
And it allows you to explore what it is to maintain
calm state of mind and body
when you have a lot of adrenaline in your system,
which certain studies are starting to show
can allow people to be able to lean into
the stressful aspects of life.
And let’s be honest, life is stressful in any event.
Now we’re all going to experience stress
at some point or another.
And when we do,
we want to make sure that we’re not overtaken
by the release of adrenaline from the adrenals,
that sudden surge of epinephrine from locus coeruleus.
So doing cyclic hyperventilation,
maybe one or two times per week,
again, 25 breaths, active inhale, passive or active exhale,
do expect to feel tingly
because of that reduction in carbon dioxide
from exhaling so much.
Do expect to feel a little bit agitated.
Be very careful doing this
if you’re somebody who has anxiety attacks
or somebody who has panic attacks or disorders of any kind.
But if you don’t and you want to explore this,
you’ll notice you start to feel really ramped up.
And then during the breath holds,
which again can be done by exhaling and stopping
for some period of time, 15, maybe even 60 seconds,
is a time in which you can explore
how to remain mentally calm.
Some people even choose to do math problems
or think of things in a kind of structured way
while they have a lot of these hormone neurotransmitters
circulating at high levels in their system.
In other words, as a way to learn to manage your mind
and body under conditions of stress.
Now, if you are somebody who’s using deliberate
cold exposure, either cold showers
or ice baths or cold immersion,
I often get asked how best to breathe
during those different types of activities.
Really, there’s no best way to breathe.
Although if you wanted to turn those activities
into their own form of stress inoculation,
again, please don’t use cyclic hyperventilation.
It’s dangerous.
I don’t recommend it whatsoever,
but you can try to actively slow your breathing.
That is to make sure that you’re engaging
in rhythmic breathing.
Now, up until now, I’ve said that rhythmic breathing
is the default.
Prebotzinger nucleus controlling rhythmic breathing
is the default.
And that doubling up on inhales and exhales
is something that happens when you deliberately
take over the action of prebotzinger complex.
Now, that’s true 99% of the time.
However, there are certain conditions
such as conditions of heightened state
of emotional arousal, right?
If you think about somebody who’s been crying,
oftentimes they’ll do the double inhale exhale.
That says, or triple inhales,
or if somebody is very, very afraid, it’s all inhales.
Okay, so it does sometimes happen spontaneously.
Actually, when we get into very cold water,
there’s a very robust decrease in the activation
of the prefrontal cortex,
which is the area of brain real estate
right behind the forehead that controls
structured thinking, your ability to reason
and make sense of what’s going on.
If you get into really cold water,
you should not expect that brain region to work
or at least not work very well at all
for the first 20 or 30 seconds that you’re in the cold water.
From the time you get into cold water,
because here we’re talking about deliberate cold exposure,
I encourage you to try and control your breathing
and make it rhythmic.
That is inhales, follow exhales, follow inhales,
follow exhales, even if they have to be fast,
inhale, exhale, inhale, exhale.
Why?
Because the default,
when we get into a stressful circumstance,
emotionally or physically stressful circumstance,
is that rhythmic breathing stops
and that parafacial nucleus takes over and it’s,
and it’s that kind of panicky mode.
And by simply controlling our breath,
again, even if it’s fast,
from inhale to exhale and making sure
that we’re alternating inhales and exhales rhythmically.
And what you’ll find is that you’ll be able to navigate
that what would otherwise be a very stressful circumstance
and make it less stressful or maybe even pleasant.
And that skill definitely translates
to other aspects of life in which, you know,
you’re hit square in the face with something stressful.
You’ll notice your breathing
and your pattern of breathing switching to multiple inhales
or, you know, a breath holding,
essentially departing from rhythmic breathing.
And by quickly returning to rhythmic breathing
and maybe even trying to slow the breathing
and extend those exhales,
you’ll find that you can very quickly calm down.
Next, I’d like to discuss what I find
to be an absolutely fascinating topic.
It’s also one that’s highly useful in the world,
which is how your specific patterns of breathing
relate to your ability to learn and to remember information,
how it can modulate fear,
and a number of other aspects of how your brain functions.
This is a literature that’s been reviewed recently
in a lot of exquisite detail in a beautiful review
by Jack Feldman, who I mentioned earlier,
one of the pioneers of the neuroscience of breathing.
The title of the review is
Breathing Rhythm and Pattern
and Their Influence on Emotion.
Again, we’ll provide a link to this review
in the show note captions.
This review includes discussion of several studies,
one in particular that I’ll get into in a bit of detail
that describes the following.
Right now, I just want you to breathe regularly,
meaning rhythmically.
You can inhale and exhale through your mouth
or through your nose.
I’d prefer that you do it through your nose
because nasal breathing,
unless you need to breathe through your mouth
because of hard exercise or eating or talking
is always going to be the better way to go.
Nasal breathing improves the aesthetic of your face.
That’s been shown.
We’ll talk about that just briefly in a few minutes.
Nasal breathing improves the amount of oxygen
you can bring into your system, et cetera, et cetera.
Okay, so just breathe.
Inhale, exhale, inhale, exhale.
And know that during your exhales,
your pupil, that is the pupil of your eye,
is getting bigger.
And as you exhale, it’s getting smaller.
In addition, when you inhale,
your reaction time to anything that happens around you,
a car swerving in front of you,
something that you might detect in the periphery
of your vision or hear off in the distance,
increases significantly compared to when you’re exhaling.
In addition, when you are inhaling,
your ability to remember things,
especially things that take a bit of effort to remember,
and your ability to learn new information
is significantly greater than it is when you’re exhaling.
Now, as you hear all that, you’re probably thinking,
okay, how do I just inhale?
Well, of course, that’s not going to be the best approach.
You need to exhale as well
for all the reasons you now are well aware of.
But what these findings really illustrate,
and I should mention,
these findings are all carried out in humans, all right?
So these relate to some stuff in animal studies,
but what I just described has been shown
in human studies consistently.
When we inhale,
and in particular, when we inhale through our nose,
our brain is not functioning in the same way
as when we exhale.
Now, that doesn’t mean that our brain is functioning
in a deficient way when we exhale.
It just doesn’t function as well
as it relates to memory retrieval, memory formation,
and some other aspects of cognition.
Now, you might be asking, why in the world would this be?
Well, I wasn’t consulted at the design phase,
and anyone that tells you that they were,
you should back away from quickly.
But one reasonable explanation
for why our brain functions better,
at least in the context of what I just talked about,
when we inhale is because the olfactory system
is actually the most ancient sensory system
of all the sensory systems we have.
So before vision, before audition, before touch,
before all of that,
the olfactory system is the most ancient system.
And the olfactory system, of course,
is designed to detect chemicals in the environment.
And so if you imagine an early organism
that perhaps we evolved from, or perhaps we didn’t,
but nonetheless, that we share some features of,
at least in terms of olfactory function,
in order to get that chemical information into the brain,
we need to inhale, we need to bring that information in.
Now, for aquatic animals,
they could take it in through water,
but for animals that are terrestrial, that live on land,
they would have to get it through the air.
So inhalation, we know, activates certain regions
of the so-called piriform cortex.
These are areas of the neocortex that are more ancient,
as well as increasing the activity of brain areas,
such as the hippocampus,
which is a brain area involved in learning and memory.
In fact, one of the studies
that illustrates this most beautifully
is a study that was published
in the Journal of Neuroscience in 2016.
By the way, Journal of Neuroscience is a very fine journal.
And the title of this paper is
Nasal Respiration in Transhuman Limbic Oscillations
and Modulates Cognitive Function.
This is a paper that followed up on an earlier paper
that showed that when people breathe in through their nose,
their recognition and their discrimination
of different odors was far greater
than when they breathed in through their mouth.
Now, that result was interesting,
but it was also sort of a duh,
because you smell things with your nose, not your mouth.
You taste things with your mouth
and you speak with your mouth,
and there are a bunch of other things
you can do with your mouth.
But nonetheless, that study pointed to the idea
that the brain is different during nasal inhalations
versus nasal exhalations
versus mouth inhalations versus exhalations.
What it basically showed is that the brain
ramps up its levels of activity,
and that signal to noise that we talked about earlier,
if you recall, that ability for the brain
to detect things in the environment
is increased during inhalations.
But because that earlier study focused on smell,
on olfaction, there was a bit of a confound there.
It was hard to separate out the variables.
So this paper, the one I just mentioned,
Nasal Respiration and Transhuman Limbic Oscillations
and Modulates Cognitive Function,
did not look at detection of odors.
Rather, it looked at things like reaction time or fear.
And basically what it found is that reaction time
is greatly reduced when people are inhaling.
So they had people look at fearful stimuli.
They looked at their reaction time to fearful stimuli.
In other words, their ability to detect
certain kinds of stimuli,
and they were given a lot of different kinds of stimuli.
So they had to be able to discriminate
between one sort of, oops, excuse me,
one, by the way, folks, for those listening,
I just bumped the microphone, getting rather animated here.
What these subjects had to do was detect
one type of stimulus versus another stimulus
that they were being exposed to.
And what they found is if people were inhaling
as that fear-inducing stimulus was presented,
their reaction time to notice it was much, much faster.
And they related that to patterns of brain activity.
And they were able to do that
because they were actually recording from the brain
directly from beneath the skull.
And they were able to do that
because they had some patients
that had intracranial electrodes embedded in their brain
for sake of trying to detect epileptic seizures.
So there’s a lot to this study
and a lot that we could discuss.
But the basic takeaway is that
when people are inhaling,
that is when they’re drawing air in
through their nose in particular,
their ability to detect what’s going on
in the world around them is greatly enhanced.
And not just for fear, but also for surprise of all sorts.
So when people are inhaling,
their ability to detect novel stimuli,
things that are unexpected
or that are unusual in their environment
is significantly increased.
Again, we’ll put a link to this study as well.
I find it to be one of the more interesting studies
in this realm.
Although there are now many additional studies
that support this statement that I made earlier,
which is that during inhalation, also called inspiration,
there are a number of very fast physiological changes,
such as changes in pupil diameter,
changes in the activity of the hippocampus,
this memory encoding and retrieval area of the brain
and other areas of the brain.
So what’s the tool takeaway from this?
If you are sitting down to read or research or study,
or you really want to learn some information,
maybe you’re listening to a podcast
or some other sorts of information that you want to retain,
it actually makes sense to increase the duration
or the intensity of your inhales as you do that.
The more that you’re inhaling relative to exhaling
in terms of duration,
the more that your brain is in this focused mode
and this mode of being able to access
and retrieve information better.
Now, there’s one caveat to this that I think is important
because I know a number of people listen to this podcast
for sake of gleaning tools,
not just for cognitive enhancement,
but for physical enhancement.
It turns out that when you are inhaling air,
you’re actually less able,
or I should say less efficient
at generating voluntary movements.
Now, that might come as a surprise.
You know, up until now,
we’ve basically been talking about inhalation is great,
almost to the point where you wonder,
like, is exhalation good for anything, right?
You don’t want to over-breathe
and kick out too much carbon dioxide.
Well, of course, exhalation is great for things.
In fact, if you’re somebody
that’s played baseball or softball,
well, what are you told?
That you should exhale on the swing
to generate the maximum amount of power.
If you’re somebody who has done martial arts of any kind,
who has traditional Western boxing,
as you strike, that’s where people typically do the hi-yah,
like in the sort of classic karate type thing.
That’s more of a movie thing.
I don’t know whether or not people actually use the hi-yah,
but in boxing, oftentimes people will do the shh.
You know, they’ll do a rapid exhalation,
a forceful exhalation,
keeping in mind, again, that inhales typically are active.
They engage the diaphragmatic muscle.
They engage those intracostal muscles,
whereas exhales tend to be passive
unless we take active control of the exhale.
And indeed, our ability to generate fast, directed,
so-called volitional, voluntary movements
is greatly enhanced if we do them during the exhale,
not the inhale.
Now, with all of that said,
I haven’t yet really talked about
mouth versus nasal breathing,
and it really can be a fairly short discussion
because what abundant data now show
and has been beautifully described
in the book called Jaws, A Hidden Epidemic.
This is a book that was written
by Paul Ehrlich and Sandra Kahn,
my colleagues at Stanford School of Medicine.
It has an introduction and a foreword from Jared Diamond
and from the great Robert Sapolsky,
so some real heavy hitters on this book.
What that book really describes is that whenever possible,
meaning unless you’re speaking or eating
or you’re exercising or other activities
require some change in your pattern of breathing,
we should really all be striving to breathe
through our nose, not through our mouth.
And that relates to the increased resistance
to breathing through the nose we talked about earlier.
Again, I’ll say it a third time,
that increased resistance through the nose
allows you to inflate your lungs more, not less.
The other thing that breathing through your nose
allows you to do is it both warms and moisturizes
the air that you bring into your lungs,
which is more favorable for lung health
than breathing through the mouth.
Hard breathing through the mouth
or simply mouth breathing at all
is actually quite damaging or can be, I should say,
quite damaging to some of the respiratory functions
of your lungs.
That of course does not mean
that you shouldn’t breathe hard through your mouth
when you’re running or sprinting or exercising hard,
but you don’t want mouth breathing
to be the chronic default pattern that you follow.
Nasal breathing is the best pattern of breathing to follow
as a default state.
Another aspect of nasal breathing that’s really beneficial
is that the gas, nitric oxide,
is actually created in the nasal passages.
It’s a gas that can cause relaxation of the smooth muscles
that relate to the vasculature, not just of your nose,
but of your brain and for all the tissues of your body.
This is why nasal breathing and not mouth breathing
is great for when you want to relieve congestion.
So a lot of these things seem counterintuitive, right?
Your nose is stuff,
so that mainly makes people breathe through their mouth,
but it turns out that breathing through your nose
will allow some dilation of the vasculature,
more blood flow, dilation of the nasal passages,
and delivery of nitric oxide
to all the tissues of your body.
And that dilation of the small capillaries
that innervate essentially every organ of your body
allow the delivery of more nutrients
and the removal of carbon dioxide
and other waste products from those tissues more readily
than if you’re not getting enough, excuse me,
nitric oxide into your system.
Okay, so a lot of reasons to be a nasal breather.
If you want to check out that book,
Jaws, Hidden Epidemics, it’s a terrific read,
and it also shows some absolutely striking pictures,
twin studies and so forth,
and some before and afters of people
and the aesthetic changes that they experienced
when they shifted from being a mouth breather
to a nose breather.
These are striking examples
that have been observed over and over again.
When people mouth breathe,
there’s an elongation of the jaw,
droopiness of the eyelids,
and the entire jaw structure really changes in ways
that are not aesthetically favorable.
Fortunately, when people switch to becoming nasal breathers,
and of course that takes some encouragement
either by mouth taping
or doing their cardiovascular exercise with mouth closed,
or by doing the sorts of exercises
that we talked about earlier,
when they switch to becoming nasal breathers by default,
the aesthetic changes that occur
are very dramatic and very favorable,
including sort of elevation of the eyebrows,
not in an artificial sense or in a kind of outrageous way,
but elevation of the cheekbones,
sharpening of the jaw,
and most notably improvements of the teeth
and the entire jaw structure.
In fact, one simple test of whether or not
you can be an efficient nasal breather,
and whether or not you’ve been nasal breathing efficiently
or most of the time in the past,
or whether or not you’ve been relying more
on mouth breathing,
that was described in the book, Jaws,
is you should be able to close your mouth
and breathe only through your nose.
Again, this is at rest,
not during exercise necessarily,
but you might do it during exercise.
But close your mouth,
put your tongue on the roof of your mouth,
and it should fit behind your teeth,
and you should be able to nose breathe in that position.
And many people won’t be able to do that,
but fortunately, as I mentioned earlier,
if you nasal breathe,
that is you deliberately nasal breathe when at rest
for some period of time,
you will experience an increased ability to nasal breathe,
and you should also experience some addition of space
within the palate of your mouth
to allow your tongue to sit more completely
on the roof of your mouth.
This is especially true for children
that perform this technique.
Again, I refer you to the book, Jaws, A Hidden Epidemic.
It’s an absolutely spectacular book.
You can also just look online
before and after Jaws, Hidden Epidemic,
and look at some of the changes in facial structure
that occur when people move from mouth to nasal breathing,
and it’s really quite striking.
So during today’s episode, per always,
we covered a lot of information.
First, we talked about the mechanical aspects of breathing,
the lungs, the diaphragm, the trachea, and so forth.
We also talked about the chemical aspects of breathing,
that really breathing is a way
that we bring oxygen to our cells
and that we get the correct levels,
or I should say we maintain the correct levels
of carbon dioxide in our system,
neither too much nor too little
in order to allow oxygen to do its magic
and to allow carbon dioxide to do its magic,
because as you learned during today’s episode,
carbon dioxide is not just a waste by-product.
It has very critical physiological functions.
You need to have enough of it around,
and therefore you don’t want to over-breathe,
especially at rest.
We talked about a tool to measure
how well you manage carbon dioxide,
the so-called carbon dioxide tolerance test,
and various exercises that you can use
simply by breathing to decrease your stress in real time,
decrease your stress chronically around the clock.
Obviously, that’s a good thing,
improve sleep, improve mood.
How to increase breath hold times,
and why you might want to do that.
Also, how to eliminate hiccups.
We talked about how to breathe
in order to eliminate the side stitch or side cramp
that you might experience during exercise,
and how to breathe in order to improve learning and memory,
reaction time, and various other aspects
of cognitive and physical function.
I do realize it’s a lot of information,
but as always, I try and give you information
that is clear, hopefully interesting as well,
and actionable toward a number of different endpoints.
So if you’re somebody that’s just now starting to think
about the application of breath work,
I would encourage you to please, yes,
do the carbon dioxide tolerance test.
That will give you some window into how well
or how poorly you’re managing breathing.
And then here’s the great news.
The great news is that breath work,
that is deliberate respiration practices,
are very effective at creating change very quickly.
In some cases, such as the use of the physiological sigh
or cyclic hyperventilation,
those changes can be experienced
the first time and every time,
because again, these are not hacks.
These are aspects of your breathing apparati,
including the mechanical stuff and the neural stuff
and the gas exchange stuff,
all of which you were born with,
and that are available to you at any moment.
So all you really have to do is explore them
and deploy them as you feel necessary.
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Once again, I’d like to thank you for today’s discussion,
all about the biology and application of breathing.
And last, but certainly not least,
thank you for your interest in science.
Thank you.