How to Breathe Correctly for Optimal Health, Mood, Learning & Performance

1. 0:00 – 5:41

   Breathing

   1. AHAndrew Huberman0:00

      (Upbeat music) 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, uh, 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, so 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, more 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.

2. 5:41 – 9:36

   Sponsors: HVMN, Thesis, WHOOP

   1. AHAndrew Huberman5:41

      Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is HVMN. HVMN, which is a supplement that increases ketones, can be used in the context of a ketogenic diet. However, many people, including myself, find that increasing blood ketones by using a supplement such as HVMN can greatly improve cognitive ability and physical output for mental work and for exercise, even when not on a ketogenic diet. There's a lot of research supporting the fact that even if you are consuming carbohydrates and you are not in ketosis, that is you are not following a ketogenic diet, consuming supplements that can increase blood ketones can allow you to think more clearly for cognitive work and physical work for that matter, perform at greater output for things like resistance training and endurance exercise, and indeed, that's what I've found. So I use it largely for preparing for podcasts or other aspects of my scientific work, and sometimes prior to workouts, especially if I'm working out having not consumed any food prior. I find that I have a lot more energy. It also has the property of suppressing hunger. If you'd like to try Ketone IQ, you can go to hmvn.com/huberman to save 20%. Again, that's hmvn.com/huberman to save 20% off your order of Ketone IQ. Today's episode is also brought to us by Thesis. Thesis makes custom nootropics, and as many of you have probably heard me say before, I am not a fan of the word nootropics because nootropics means smart drugs, and frankly, the brain doesn't work that way. The brain has neural circuits for focus. It also has neural circuits for creativity and neural circuits for task switching and for imagination and for memory. There is no such thing as a neural circuit for being smart, and therefore the word nootropics doesn't really apply to anything specific neurobiologically speaking. Thesis understands this, and therefore has designed custom nootropics that are tailored to your unique needs. I've been using Thesis for over a year now, and their nootropic formulas have been a game changer for me, in particular in the realm of cognitive work. My go-to formula for when I'm doing any kind of cognitive work is their Clarity formula. That's the one I've been using most often lately. If you'd like to try Thesis customized nootropics, you can go online to takethesis.com/huberman. You'll take a brief three-minute quiz, and Thesis will send you four different formulas to try in your first month. Again, that's takethesis.com/huberman and use the code Huberman at checkout for 10% off your first box. Today's episode is also brought to us by Whoop. Whoop is a fitness wearable device that tracks your daily activity and your sleep, but goes beyond that by providing real-time feedback on how to adjust your training and sleep schedule to perform better. I've been working with Whoop on their scientific advisory council to help Whoop evolve their mission to improve the way that people are sleeping and thereby to improve their levels of focus, mood, and alertness, and performance in all endeavors during the day. As a Whoop user, I've experienced the health benefits, the focus benefits, essentially all of the major benefits that come with getting an excellent night's sleep on a consistent basis. I've also learned from using my Whoop how certain daily activities like the timing of exercise, caffeine, and a number of other things impact the depth, quality, and duration of my sleep. Whoop is one of those tools that can really help guide you and provide you with personalized data, recommendations, and coaching around your body and your overall health. So it's not just about tracking sleep, it's about tracking all aspects of your activity and health, and of course, including sleep. If you're interested in trying Whoop, you can go to join.whoop.com/huberman today and get your first month free. 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

3. 9:36 – 18:18

   Respiration, Oxygen & Carbon Dioxide

   1. AHAndrew Huberman9:36

      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? W- 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 and say, "Well, 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 and 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, uh, 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 (inhales deeply) and then the second one after that is (inhales sharply) a quick sharp inhale to maximally inflate your lungs, followed by a full exhale through the mouth till 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 actually performs during sleep on a pre- 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

4. 18:18 – 30:08

   Breathing Mechanics

   1. AHAndrew Huberman18:18

      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. All right? 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 sacks that are called the alveoli of the lungs. And by having those hundreds of millions of little sacks, 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 sacks, and you allow more carbon dioxide to move from the bloodstream into those sacks of the lungs, and then when you exhale, the carbon dioxide can be removed. Okay? So those little sacks we call alveoli of the lungs are i- 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 got, 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. Now, 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 do- 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 ribcage to move up and to expand a bit. And 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 ribcage actually moves up, sometimes the shoulders will move up as well, and th- that's because those intercostal muscles are contracting. Now, muscles can't move on their own. They are controlled by nerves. So 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 m- contracting your biceps or you're walking and you're contracting your cr- 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 there are little neurons that reside in the brain stem, 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 intercostal muscles. And there's a separate set of nerves that allow those muscles to contract and for your ribcage to expand in order to create more room for your lungs to get larger and fill with air, or for your ribcage 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 ribcage moves. This is a common misconception. People say, "Oh, you know, if your shoulders are going up and down and your, your ribcage is moving while you're breathing, well then you're not breathing right. And if your belly goes out and, uh, the rest of your body is still while you breathe, well then you're breathing correctly." I know of zero, uh, 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 intercostal muscles and your ribcage 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 ribcage-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, right? Once again, just to review, it's nose, mouth, larynx, lungs, alveoli within the lungs, and then those two muscles, the diaphragm and the intercostal 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, 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, a bellow pump where you can, y- 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, or the walls of the larynx were very flimsy and thin, well, then you can imagine breathing in very vigorously and (popping noise) it would shut like a tube, uh, that suddenly flattens on itself, which is, (laughs) 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 (inhales deeply) and only through your mouth versus breathe in through your nose (inhales sharply) . 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 cerebral spinal 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. A little bit later, we'll talk about how to repair a deviated septum without surgery 'cause that actually is possible in many, not all cases, and is ex- 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 are actually able to draw more force into these mechanical aspects of the breathing apparatus and actually bring more air into your lungs. Okay. 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. D- 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 in, uh, together, and I can prove, uh, to everyone that, um, I'm just as deficient in this as you are. (inhales deeply) 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. (inhales sharply) And you'll feel your entire cavity, your, 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, uh, 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, is a vitamin mineral probiotic drink that covers all of your foundational nutritional needs.

5. 30:08 – 31:23

   AG1 (Athletic Greens)

   1. AHAndrew Huberman30:08

      I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or usually twice a day is that it gets me the probiotics that I need for gut health. Our gut is very important. It's populated by, uh, gut microbiota that communicate with the brain, the immune system, and basically all the biological systems of our body to strongly impact our immediate and long-term health.And those probiotics in Athletic Greens are optimal and vital for microbiotic health. In addition, Athletic Greens contains a number of adaptogens, vitamins, and minerals that make sure that all of my foundational nutritional needs are met, and it tastes great. If you'd like to try Athletic Greens, you can go to athleticgreens.com/huberman, and they'll give you five free travel packs that make it really easy to mix up Athletic Greens while you're on the road, in the car, on the plane, et cetera, and they'll give you a year's supply of vitamin D3 K2. Again, that's athleticgreens.com/huberman to get the five free travel packs and the year's supply of vitamin D3 K2. 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

6. 31:23 – 40:35

   Chemistry of Breathing, Hyperventilation

   1. AHAndrew Huberman31:23

      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, uh, 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, 'cause 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 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. (laughs) Um, 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, for 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, al- 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 that 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, or a- 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. It's probably safe to do 25 or 30 deep inhales and exhales, and you'll notice that by about breath ten, 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, an increase in the activity of your overall sympathetic nervous system, which has nothing to do with sympathy. It 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. (breathing) Now, by breath eight or nine or ten, you'll notice that your body starts to heat up. That's due to a couple of things, uh, mainly the release of adrenaline from your adrenals. I'm already feeling a little bit light-headed. The light-headedness 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, all right? Hypoxia, hypo-xia, 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

7. 40:35 – 47:16

   High Altitudes, Oxygen & Breathing

   1. AHAndrew Huberman40:35

      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, you know, 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, uh, way up high? Well, a lot of people 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 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 (gasps) 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 (inhales) for those of you listening, I just took a bin- 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 (exhales) ... (inhales) 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 (inhales sharply) 'cause 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 ni- original position. So inhaling is active, and exhaling is passive. And so what happens is, well, 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. Uh, I mention all that because, yes indeed, there are some changes in the atmospheric gases at high altitudes, and, uh, 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 could 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 that 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, uh, 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 intercostal 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 (inhales sharply) 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 that 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- an usual 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, um, across the body and with the- 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

8. 47:16 – 51:50

   Tool: Sleep Apnea, Nasal Breathing

   1. AHAndrew Huberman47:16

      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, um...... 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, an 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, th- 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 started to run out of air, um, 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, um, a- any number of things that are sort of, 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, a sle- 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, uh, 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

9. 51:50 – 57:23

   Brain Centers & Breathing Rhythm

   1. AHAndrew Huberman51:50

      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-Botzinger 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 100 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 brain stem area, so in the, you know, around the region of the neck, called the pre-Botzinger 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 in, 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 pre-Botzinger 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, uh, hopefully, I think we, frankly, can expect that it's also going to eventually lead to ways to prevent death, uh, in people using opioids or other types of drugs, maybe by blocking opioid receptors in pre-Botzinger complex using things like naltrexone, et cetera. In any event, pre-Botzinger complex is controlling inhale, exhale, inhale, exhale 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 in these intercostal 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, inhale followed by exhale. That is, it's not rhythmic, one then 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 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-Botzinger complex neurons to reliance on the parafacial nucleus neurons and box breathing. Just to give away what's probably already obvious, as 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-Botzinger 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 (inhales) and then force the air out. (exhales) That's going to represent a conscious taking over of control of the pre-Botzinger 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-Botzinger 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 any time 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-Botzinger, 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 in the lungs, et cetera, and the muscles involved in

10. 57:23 – 1:03:53

    Brain, Hyperventilation & “Over-breathing”

    1. AHAndrew Huberman57:23

       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 Balestrino and Somjen, 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 Balestrino and Somjen 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 Balestrino and Somjen 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, 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 this study in the show note captions. It's a somewhat complicated paper, w- 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 they're, 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- 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 hyperexcitable. It's as if it's being starved of oxygen and blood flow, and all the neurons, in a very non-specific way, start increasing their firing levels, so the background activity is getting louder and louder, it's like the rumble or 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 hyperexcitable. 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 hyperexcitability 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

11. 1:03:53 – 1:08:26

    What is Healthy Breathing?

    1. AHAndrew Huberman1:03:53

       of air, and we're not going to go measure our lung capacity, or at least most of us aren't going to do that. Basically, if you are taking relatively shallow breaths and you're just, um, 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 shallowish breaths. And when I say shallow, I don't mean, you know, (sharp breaths) 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 (inhales) and then you expel that air, well then for- 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 sys- 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 so as a consequence, they over-breathe. And as I told you before, when people over-breathe, their brain becomes hyperexcitable at the level of the background noise, and yet they are less efficient at detecting and learning information. 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 hyperexcitability that it 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. I'd like to just take a brief moment and thank one of our podcast sponsors, which is InsideTracker. InsideTracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and

12. 1:08:26 – 1:09:44

    InsideTracker

    1. AHAndrew Huberman1:08:26

       help you reach your health goals. I've long been a believer in getting regular blood work done for the simple reason that blood work is the only way that you can monitor the markers such as hormone markers, lipids, metabolic factors, et cetera, that impact your immediate and long-term health. One major challenge with blood work, however, is that most of the time it does not come back with any information about what to do in order to move the values for hormones, metabolic factors, lipids, et cetera, into the ranges that you want. With InsideTracker, changing those values becomes very straightforward because it has a personalized dashboard that you can use to address the nutrition-based, behavior-based, supplement-based approaches that you can use in order to move those values into the ranges that are optimal for you, your vitality, and your longevity. InsideTracker now includes a measurement of apolipoprotein B, so-called apo b, in their Ultimate Plan. Apo b is a key marker of cardiovascular health, and therefore there's extreme value to knowing your apo b levels. If you'd like to try InsideTracker, you can go to insidetracker.com/huberman to get 20% off any of InsideTracker's plans. Again, that's insidetracker.com/huberman to get 20% off. 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 a non-healthy state. But the first thing we have to do, of course, is determine whether or not you're

13. 1:09:44 – 1:22:39

    Tool: Train Healthy Breathing, Carbon Dioxide Tolerance Test & Box Breathing

    1. AHAndrew Huberman1:09:44

       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, uh, 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. So 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 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. Uh, this will be one of the rare instances in this podcast where, um, there's going to be a long period of silence, a- 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 note 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 expelling your air in a slow lungs, uh, 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 gonna 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 gonna 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, (laughs) I wanna 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 an 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, other low, medium, or high bracket number for carbon dio- 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 size 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, uh, of course, if you are in the long category of carbon dioxide discard rate, you should be able to do an eight to ten second inhale, eight to ten second hold, eight to ten second exhale, eight to ten 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 neuromechanical 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 in- 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, and 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, 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's g- would be near impossible for you to do box breathing for two or three minutes with eight

Episode duration: 2:18:49