PDF Summary:Breath, by James Nestor

As we try to lead healthier lives, one thing we rarely consider is being mindful of how we breathe. Science journalist James Nestor argues that while the power of the breath is central to many Eastern traditions, it’s been largely ignored in the Western world. Modern medicine treats chronic congestion, sinus infections, and lung disease but puts little emphasis on teaching people how to breathe correctly. However, Nestor asserts that by learning how to breathe well, we’ll improve our well-being, balance our emotions, and find more energy to live the lives we want.

This guide will explain what Nestor says about how we’re breathing wrong, how we can do it better, and what amazing impact the power of breath can have over the body. We’ll also explore the underlying science of breath, hear what medical research says about Nestor’s claims, and delve into specific breathing techniques that the author recommends.

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(Shortform note: While Nestor is correct to point out that breathing is central to many belief systems and meditative practices, he understates the amount of research that modern medicine has invested in the scientific aspects of breath control. A review of medical literature reveals a wide scope of studies on the mental and physical benefits of controlled breathing.)

Breathe Through Your Nose

The first and most important step Nestor advises is to retrain yourself to use your nose and not your mouth to breathe. Your nose and sinus cavity are specifically designed to process air in ways your mouth can’t. Breathing through your nose strengthens your airways, regulates your metabolism, and even has a positive effect on the brain.

The immediate effect of breathing through your nose is that the tissues in your sinus and the back of your throat cease to atrophy from lack of use. As with muscles, the sinus and throat will grow stronger with exercise; they will soon function better and allow for a healthier airflow. Meanwhile, the nose’s cilia (fine hairs) and turbinates (boney structures) heat and clean the air you inhale so your lungs can extract more oxygen from it. The sinus also releases nitric oxide into the body, which widens blood vessels and increases circulation. In the author’s self-experiment, when he unplugged his nostrils, in only a few days his blood pressure went down and his blood’s carbon dioxide returned to normal.

(Shortform note: The anatomy of the nose and sinus cavity is even more complex than Nestor’s description indicates. It’s an ornate structure of cartilage, bone, skin, fatty tissue, three pairs of turbinates, and four pairs of sinuses. In addition to the infections and congestion Nestor warns of, it’s also vulnerable to nosebleeds, cancer, injuries, and genetic disorders. While scientists confirm Nestor’s assertion that nitric oxide is crucial to supplying oxygen to the body, it’s still not fully understood how or where it’s produced in the nasal cavity, though current evidence points to the paranasal sinuses, which were long considered to be unimportant organs.)

But it’s not just the act of breathing that does this. Nestor writes that there is a nasal cycle in which the right and left nostril alternate to control body temperature, blood pressure, and brain chemicals. (If you notice from time to time that one nostril congests while the other stays open, and then they mysteriously switch later on, this is the nasal cycle in action.) When breathing through your right nostril, your pulse, blood pressure, body temperature, and cortisol levels increase. Breathing through the left nostril has the opposite effect, and cycling between the two maintains your body’s balance. Breathing through your mouth, on the other hand, disengages the nasal cycle completely, depriving you of its body-regulating benefits.

Furthermore, the nasal cycle helps regulate the brain. The right nostril is connected to the sympathetic nervous system, raising alertness and logical thinking. Likewise, the left nostril is linked to the parasympathetic nervous system, affecting creativity and abstract thought. By switching the breath back and forth between the two, the body maintains mental equilibrium between states of relaxation and alertness.

The Nasal Cycle

It’s not accurate to describe the nasal cycle as “breathing through one nostril at a time,” when in fact the distribution is closer to 75% through one and 25% through the other at any given period, nor is it true that everyone has a nasal cycle at all. It’s only observed in 70-80% of the population, and in only half of those is the cycle truly periodic.

The nasal cycle is present in all mammals, not just humans, and is powered by asymmetrical blood flow to the sinuses. Studies confirm a loose correlation between the dominant nostril and the opposite hemisphere of the brain, but other research suggests that the cycle’s function in the body is to allow cells on either side of the nasal passage to recharge while alternating between air-conditioning and mucus-clearing processes.

Slow Your Breath Down

While switching to breathing with our noses may seem simple, the next step will take more concentration and practice. According to Nestor, our optimal breath rate is slow—much slower, in fact, than what we’re used to. To explain why this is, we must understand the vital role that carbon dioxide plays in our body chemistry and how breathing slowly will affect our chemical balance. Beyond that, Nestor asks us to consider the benefits of not only breathing slowly, but breathing less air all at once.

The science we’re taught in school is basically true—we inhale oxygen and exhale carbon dioxide. What’s false, says Nestor, is the implication that carbon dioxide is merely a waste product, when in fact it’s a vital part of the chemical exchange that gives the oxygen in our blood access to our organs. As our muscles and organs do more work, they burn energy and create carbon dioxide, which releases oxygen from the hemoglobin in our blood cells. As stated earlier, heavy breathing purges carbon dioxide from the body, which short-circuits the necessary chemical exchange and starves our cells of the very oxygen they need.

The Right Amount of Carbon Dioxide

Most of the carbon dioxide in our bodies is not present in its common chemical state, but as a component of bicarbonate and carbonic acid. Doctors measure the amount of carbon dioxide in the blood in terms of milliequivalents per liter, defining normal levels as being between 20-29 milliequivalents per liter, though a 2018 study suggests that a range of 23-30 might be more accurate.

While a certain amount of carbon dioxide is necessary to maintain our body chemistry, a build-up of too much carbon dioxide from shallow breathing can result in respiratory acidosis, a condition in which the body can’t expel carbon dioxide at a fast enough rate. Respiratory acidosis can be caused by asthma, obesity, or diseases that damage the chest’s nerves and muscles. Symptoms of respiratory acidosis include headaches, fatigue, feeling out of breath, and may even become a chronic condition leading to mental problems, hypertension, and possibly heart failure.

Nestor writes that breathing more slowly doesn’t lower the amount of oxygen in the body, but it does increase the amount of carbon dioxide, allowing more of the oxygen to be absorbed. When we breathe “normally,” we only absorb about 25% of the oxygen we take in. On the other hand, slow breathing lets us absorb more oxygen using fewer breaths—a more efficient process for the whole body that uses less work to produce more energy. Oxygen flow to the brain increases, and all our other bodily functions align themselves to work at top efficiency.

(Shortform note: This claim of Nestor’s may be overstated. Research has shown that slow, controlled breathing increases oxygen saturation levels in people with conditions such as chronic heart failure, but others argue that it has no such effect on otherwise healthy people. However, studies confirm that slow breathing increases blood oxygenation for people at high elevations. To what extent this applies at lower altitudes is unclear.)

The idea of breathing more slowly isn’t new. Spiritual practices from all around the world have ritualized slow breathing in the form of meditations, chants, and prayers. Nestor points out that all these disparate traditions, whether Tibetan or Catholic or Native American, have settled on approximately the same ideal breath rate: 5.5 seconds to breathe in, 5.5 seconds to breathe out. This, it seems, is the ideal rate of breath to bring the body and mind into alignment.

(Shortform note: Different breathing practices and their associated benefits vary more than Nestor suggests, though they’re in the same ballpark. Research on long-time yoga practitioners found that they pace their breathing at 3-4 breaths per minute, slower than Nestor’s ideal rate. Studies on heart rate variability, an indicator of cardiovascular health, show that it peaks at a rate of 8 breaths per minute, 50% faster than Nestor recommends. In the relaxation technique called box breathing, you inhale for 4 seconds, hold your breath for 4 seconds, exhale for 4 seconds, and pause for 4 seconds, for a total of 5 breaths per minute.)

Hypoventilation

Some researchers believe that breathing less air can increase the body’s overall performance. Known as “hypoventilation training,” this involves limiting your inhalations during exercise while extending the time you take to exhale. This accustoms the body to higher carbon dioxide levels and trains you to take in less air while resting. Studies have shown that this practice heightens athletic performance and is beneficial to people who suffer from asthma. Patients undergoing hypoventilation therapy developed higher resting carbon dioxide levels and fewer asthma attacks. Nestor admits that hypoventilation isn’t for everyone, in particular people who have emphysema (and therefore, already high levels of carbon dioxide).

(Shortform note: For more information, Nestor points readers to the Association for Research and Promotion of Hypoventilation Training. A study of hypoventilation in basketball players suggests that it improves the reoxygenation of muscles after bursts of exertion such as sprinting, leading to shorter recovery times. However, studies also show that voluntary hypoventilation leads to muscles deoxygenating faster in sprints than in people breathing normally while performing the same activity.)

He also states that no one’s really sure why hypoventilation training works. The leading theory is that it affects the body’s pH level (the body functions best at pH 7.4). Our “normal” practice of overbreathing makes the blood more alkaline, and other organs such as the kidneys have to release chemicals into the blood to compensate, which over time depletes the body’s minerals. Breathing less air, then, resets our pH without putting extra stress on the body’s resources.

(Shortform note: There are many factors besides overbreathing that can alter the body’s pH. Obesity, lung and heart problems, aspirin, and opiates can all make the blood more acidic, while dehydration, vomiting, diuretics, and antacids can make the blood more alkaline. Doctors treat pH imbalances with a variety of medications and therapies, depending on the specific condition, but you can also maintain your pH balance by eating right and drinking enough water.)

Strengthen Your Diaphragm and Mouth

Now that we’ve examined the benefits of breathing through your nose and slowing your breath, we’ll discuss how to strengthen your body’s breathing apparatus. Nestor focuses on two particular areas: the diaphragm muscle that drives your breathing and the muscles and bones of the face that support your vital airways. Training the diaphragm to work harder has been shown to help both patients with breathing problems and Olympic athletes, while strengthening the muscles of the face can help anyone undo the damage of a life of soft foods.

(Shortform note: Since the diaphragm doesn’t press against the skin, it’s a muscle many people aren’t even aware of. As the horizontal muscle attached to the base of the ribcage, the diaphragm separates the chest from the upper abdomen. In addition to pumping the respiratory system, it regulates the pressure that pushes matter through the gastrointestinal tract. The diaphragm is divided into three major sections—sternal, costal, and lumbar—and has several openings for blood and other fluids to pass from upper to the lower part of the body.)

Strengthening the diaphragm has long been the province of vocal coaches, in particular choir director Carl Stough, whose success training singers to improve their lung capacity led him to join forces with doctors treating people with tuberculosis. By training the patients to better use their diaphragms, they were able to regain more use of their lungs and improve their quality of life. Driven by the diaphragm, the pressure of our lungs breathing in and out creates a process called the thoracic pump, which brings blood back to the heart to replenish it with oxygen. Stough went on to bring his diaphragm-strengthening techniques to athletic training, enabling several Olympians to break their personal records in the 1968 games.

(Shortform note: Diaphragm breathing has long been a staple of musical training for vocalists and is also key to meditation because of how effectively it reduces feelings of stress. Long after Carl Stough’s work in the 1960s, studies have shown that diaphragm breathing during exercise reduces the imbalance between free radicals and antioxidants (oxidative stress) caused by exhaustive workouts. For athletes, it’s been suggested that diaphragm breathing improves coordination, reaction time, and the ability to process new information.)

In order to maximize the benefit of diaphragm training, it’s vital to open your airways. Nestor says that to do this, you should learn to maintain good oral posture, holding your mouth closed with your teeth gently touching and your tongue against the roof of your mouth. This positions your face to maximize the airways that allow you to breathe through your nose.

(Shortform note: In Breath’s appendix, Nestor directs readers to Andrew Weil’s 4-7-8 Breath Technique that combines diaphragmatic breathing with proper positioning of the teeth and tongue. Physiologists add that holding your tongue at the roof of your mouth increases the stability of your head, neck, and spine.)

Oral posture is hard to maintain if your face is out of shape from a lifetime of soft foods, but it can be toned and strengthened like any other part of your body. Nestor explains that the maxilla (the primary facial bone) is more malleable than any other in the body—it can grow and reshape itself all our lives. It does this via stem cells in the seams between the bones in your skull, cells that are activated by the act of chewing. Therefore, eating hard, unprocessed foods promotes increased bone mass in your face and strengthens the muscles that hold your airways open. You can also increase bone mass by using an oral appliance designed to widen the mouth.

The Medical View on Reshaping the Face

The ability of the face to widen and redevelop bone structure on its own is still a subject for debate. Surgical methods are commonly used to widen narrow mouths as a precursor to other corrective dental procedures. However, research shows that non-surgical methods using dental appliances can have similar results with negligible complications.

The specific oral device Nestor references is the Homeoblock, developed by dentist Theodore Belfor. A clinical study at Montefiore Medical Center to evaluate the Homeoblock’s effectiveness at expanding the maxilla, palate, and jawbone, as well as its viability as a CPAP alternative for people with sleep apnea, is currently under review.

Extreme Breathing Techniques

While researching the intricacies of how breathing works and how we can train ourselves to do it better, Nestor came across many unusual breathing practices and techniques. He doesn’t explicitly recommend readers try them, certainly not without expert supervision, but he presents them as examples of the power of the breath to affect the body and mind.

From Tibetan monks to athletes and psychologists, there are those who have found ways to use controlled breathing to alter mental states and perform seemingly miraculous feats of physical endurance. Nestor writes about several such practices—the art of using the breath to control body temperature, the use of carbon dioxide to reset the brain’s chemoreceptors, and ancient yogic practices that can affect the autonomic systems of the body.

But how is this possible? The simplest explanation is that breathing is the one bodily function in which our conscious and unconscious systems overlap. Just as your heart regulates blood flow, your stomach digests food, and your immune system fights off infection, your respiratory system needs no conscious control. However, unlike our body’s other autonomic systems, we can purposefully alter our breath. The respiratory system is an opening through which we can consciously influence other autonomic functions. In computer terms, the lungs provide an exploit that we can use to control parts of our bodies that we wouldn’t otherwise have access to.

Two Sides of Breathing

How breath can be voluntary and involuntary isn’t fully understood. There appear to be separate neural pathways that regulate breathing, but where they connect in the brain is uncertain. What’s clear is that there isn’t one “pacemaker” signal, as there is for the heart, though doctors have developed artificial pacemakers for the diaphragm. However, the lungs are regulated by complex biofeedback systems that begin long before we take our first breath.

It’s possible that the connection between breathing and voluntary action goes both ways—one study reveals that our “readiness potential” for voluntary behavior is highest when we exhale, suggesting that how and when we breathe has a strong effect on how and when we act.

Hacking the Nervous System

To understand how this works, Nestor explains how the lungs interact with two different parts of the autonomic nervous system. Different nerves are connected to different parts of the lungs, so by making your breath shallower or deeper, you can deliberately trigger different responses in your body. Nestor describes what the different triggers do, how Tibetan monks developed this practice to survive in the frigid Himalayan heights, and how Dutch athlete Wim Hof uses the same techniques to perform incredible acts of endurance.

(Shortform note: Wim Hof’s technique, described in The Wim Hof Method, grew out of his experimentation with combining different breathing practices with exposure to cold water. However, in his book, Hof espouses cold exposure as the first important step before moving on to controlled breathing. He couples both of these to adapting the right mindset, which he says is crucial to obtaining all the benefits of his program.)

According to Nestor, the autonomic nervous system is actively regulated by breathing. It’s broken into two parts: the parasympathetic nervous system, which triggers rest and relaxation, and the sympathetic nervous system, which gears our bodies up for action. The parasympathetic nervous system is connected to the lower parts of our lungs, which is why slow, deep breaths are calming. Conversely, the sympathetic nervous system is tied to the lungs’ upper regions. Short, rapid breaths that only reach the top of the lungs trigger the sympathetic nerves into action, putting your body into a heightened state of stress. Evolution designed that heightened state for our survival, but the body isn’t meant to stay in it for long.

(Shortform note: The sympathetic and parasympathetic nervous systems are located in different parts of the body. The sympathetic system is predominantly centered on the spinal column, while the parasympathetic system is located between the top of the spine and the medulla. Though both systems regulate the same internal organs, the effects they have are different. In general, the sympathetic system increases bodily function, while the parasympathetic system slows down body activity.)

Nestor writes that a breathing technique known as Tummo (or “inner fire”) was developed in Tibet 1,000 years ago. The practice involves taking a series of breaths into the lower lungs, releasing them with a wavelike motion from the abdomen. After exhaling the final breath, you hold it for as long as you can, then follow that with an enormous inhalation, which you also hold for as long as you can. Nestor repeats that this shouldn’t be attempted without supervision or by anyone with a heart condition.

Tummo activates the sympathetic nervous system and allows a practitioner to remain in that state for extended periods of time. Doing so keeps the body warm, allowing Buddhist monks to weather the extremes of high-altitude cold. Because this technique goes against the body’s natural cycles, though, it can be dangerous and its use was restricted to those who had undergone rigorous training.

(Shortform note: In his notes, Nestor cites a 2013 study comparing expert Tibetan practitioners of Tummo with a control group of people trained in the Tummo breathing technique but not the meditative component of the practice. The study found that both groups were able to use the breathing technique to raise their body temperature, but those who had mastered the meditative component were able to sustain the higher temperature for a longer duration.)

Slowly this technique has made it to the outside world. Some soldiers, athletes, and martial artists have used versions of it to prime their bodies for periods of extended exertion. Tummo found its ultimate modern expression in the Dutch athlete and motivational speaker Wim Hof, who has demonstrated its power to ward off frostbite, exhaustion, heatstroke, and even infection. Hof has touted his techniques as beneficial, but Nestor points out that to date, no one knows the long-term effects of activating the sympathetic nervous system for long periods.

(Shortform note: To be fair, Wim Hof does not recommend extended periods of cold exposure and breathwork. In The Wim Hof Method, he recommends practicing the two elements separately and not attempting his breathing technique anywhere that you might endanger yourself by passing out. The ultimate goal of Wim Hof’s technique isn’t to duplicate his feats of physical endurance but to better understand and control your own body.)

Resetting Your Fear Response

While bringing air into different parts of your lungs can trigger different responses in your body, you can also affect unconscious responses by exposing yourself to excess carbon dioxide. In particular, the brain’s chemoreceptors, which act as a fear alarm system for the body, can be trained to have a higher carbon dioxide tolerance. Nestor describes how our chemoreceptors work, the benefits of pushing their limits, and how carbon dioxide therapy has been used to treat a myriad of problems.

The primary function of the chemoreceptors found in the central brainstem is to monitor the amount of carbon dioxide in the blood, telling our lungs when to breathe. If they sense that our carbon dioxide levels are too high, they activate a panic response completely independent of the one in our amygdala. It’s the fear of suffocation or drowning, and it can override any other conscious response. For those with sleep apnea, it’s what wakes you up at all hours of the night. The chemoreceptor response can also be tickled throughout the day if prolonged distraction results in shallow breathing (a condition Nestor describes as “email apnea”).

Your Body’s Chemoreceptors

Nestor erroneously implies that the amygdala itself isn’t a chemoreceptor that monitors carbon dioxide levels, when in fact, it is. However, some researchers differentiate between fear and panic. Fear, governed by the amygdala, is a response to external threats, while panic, induced by internal triggers, is the domain of the body’s other chemoreceptors.

In Breath’s appendix, Nestor points out that there are actually two types of chemoreceptors in your body—the central chemoreceptors that monitor the pH of your spinal fluid, and the peripheral chemoreceptors that monitor levels of oxygen and carbon dioxide in the blood. In addition to responding to hypoxia in the way that Nestor describes, the chemoreceptors can also be triggered by changes to your body’s pH due to vomiting, diarrhea, and acidosis.

Nestor suggests that if your chemoreceptors can be trained to tolerate higher levels of carbon dioxide, it opens up a range of possibilities. Flexible chemoreceptors let people adapt to high altitudes or dive to the depths of the ocean. Since carbon dioxide in the body promotes oxygen delivery to organs, trained chemoreceptors can extend the usefulness of every single breath. Furthermore, because chemoreceptors are closely tied to our primal fear response, widening their tolerance range can be useful in treating anxiety and other neurological conditions.

Carbon dioxide therapy is a technique developed by physicians in the early 20th century to reset oversensitive chemoreceptors by raising the body’s carbon dioxide levels. Patients were made to breathe a mixture of 70% oxygen and 30% carbon dioxide, which initially provokes a feeling of suffocation even though the body is being supplied with more than enough oxygen to survive. Repeated exposure was found to alleviate symptoms of anxiety and even wake patients out of catatonic states. Nestor writes that by the 1950s, doctors switched to medication as their primary form of treatment, though research on carbon dioxide therapy resumed in the 1980s.

The Health Benefits of Carbon Dioxide

A specific study from the 1950s indeed suggests that inhaling carbon dioxide is a useful therapeutic tool for phobias and anxiety, and even some other neurological conditions (such as migraine headaches). However, the same study notes that while carbon dioxide therapy can be effective on its own, it’s even more so when coupled with traditional psychotherapy.

A more common form of modern carbon dioxide therapy involves absorbing or injecting carbon dioxide in the skin, rather than inhaling it. Instead of resetting chemoreceptors, this technique is used to heal wounds, reduce cellulite, and treat nerve damage caused by diabetes.

The Breath of Life

As scientists and physicians work to better understand the ways that breath regulates our body’s functions, practitioners of several ancient traditions have used breath to master the body for thousands of years. In many cultures, breath is believed to be the energy of life, an energy that can be manipulated to spectacular effect. Nestor briefly outlines the nature of these beliefs and cites the example of Swami Rama, whose amazing, breath-induced control of his body was documented by scientists in a 1970 study.

Sages and healers in India and China identified breath—known as prana to students of yoga—as the energy of life as many as 3,000 years ago. The practices of yoga go back further still, to images passed down from the Indus Valley civilization dating 5,000 years before the present, although yoga’s early forms were not as they are today. Nestor says that while modern yoga emphasizes movement and poses, ancient yoga focused on sitting and breathing.

(Shortform note: Although modern yoga has been heavily secularized, its roots lie in ancient Hindu traditions. According to the Hindu Upanishads, prana is not just the life force inside us, but is also the life force of the universe itself. The breath control aspect of yoga, pranayama, employs several different breathing techniques which, when combined with meditation, have documented physiological and psychological benefits.)

In these practices, breath is the process by which prana—the life force—is built up and distributed throughout the body. Yogic masters are reportedly able to move and manipulate the energy of prana inside them. Science has never established prana’s existence, though scientists at the Menninger Clinic made intriguing observations in 1970. They subjected a yoga teacher named Swami Rama to a battery of tests, during which he was able to consciously alter his heartbeat, body temperature, and even his brain waves, all through the power of controlling his breath.

(Shortform note: As Nestor notes in his bibliography, the results of the observations made on Swami Rama were reported in the New York Times in 1971. However, there has been little follow-up to corroborate the results of the Menninger Clinic’s experiments. Additionally, throughout the 1970s and ’80s, several women came forward to accuse Swami Rama of sexual misconduct, as well as fraud and acts of misrepresentation, tarnishing his credibility as a spiritual leader.)

No solid theory has been able to explain how Swami Rama was able to perform these feats, though Nestor suggests that the most plausible guess has to do with how oxygen affects the flow of electrons through the body. Many mysteries remain about how breath drives the body, and much research remains to be done. However, Nestor strongly asserts that how we breathe dictates how well we live and deserves as much attention as any other vital part of our lives.

(Shortform note: In his discussion of prana, Nestor characterizes it as a form of energy, in keeping with the terminology used by yogic practitioners. Scientists often object to the way mystics and meditative experts use the word “energy” to describe what can appear to be purely imaginary forces, but the problem arises because even in science, the concept of energy is especially hard to define. In our bodies, energy is stored in the molecular bonds of glucose and released through various chemical interactions. If yogic practices are truly able to manipulate energy in the biochemical sense, it must therefore be through using the breath to trigger unconscious chemical processes.)