Nine
HOLD IT
In 1968, Dr. Arthur Kling left his office at the University of Illinois Medical College and caught a flight to Cayo Santiago, a wild and unpopulated island on Puerto Rico’s southeast coast. He grabbed some traps, captured a group of wild monkeys, then took the animals back to the lab to conduct a bizarre and cruel experiment. Kling began by opening the monkey’s skulls and removed a dollop of brain from each side. He let the monkeys recover, then released them back into the jungle.
Beyond a few scars on their heads, the monkeys looked normal, but something was wrong inside their brains. They had trouble navigating the world. Some starved to death. Others drowned. A few were quickly devoured by other animals. Within two weeks, all of Kling’s monkeys were dead.
A couple years later, Kling traveled to Zambia, just upstream from Victoria Falls, and repeated the experiment. Within seven hours of releasing the altered monkeys back into the wild, all had disappeared.
The monkeys all died because they couldn’t recognize which animals were prey and which were predators. They didn’t sense the danger of wading into a rushing river, swinging from a thin branch, or approaching a rival troop. The animals had no sense of fear, because Kling had removed fear from their brains.
Specifically, Kling had clipped out the monkeys’ amygdalae, two almond-size nodes at the center of the temporal lobes. The amygdalae help monkeys, humans, and other high-order vertebrates remember, make decisions, and process emotions. These nodes are also believed to be the alarm circuit of fear, signaling threats and initiating a reaction to fight or run away. Without the amygdalae, Kling wrote, all the monkeys “appeared retarded in their ability to foresee and avoid dangerous confrontations.” Without fear, survival was impossible, or, at minimum, extremely precarious.
Back in the United States, a girl whom psychologists would name S. M. was born around this time with a rare genetic condition called Urbach-Wiethe disease. The condition caused cell mutations and a buildup of fatty material throughout her body, giving her skin a lumpy and puffy appearance and making her voice hoarse. When S. M. was ten, the deposits had spread into her brain. For reasons nobody understands, the disease left most regions unharmed, but destroyed her amygdalae.
S. M. could see, feel, hear, think, and taste just like anyone else. She had a normal IQ, memory, and perception. But as S. M. entered her late teenage years, her sense of fear diminished. She would approach total strangers, stand a few inches from their faces, and describe her most intimate sexual secrets, never afraid of embarrassment or rejection. She’d walk outside in a violent thunderstorm to chat with a neighbor, never worrying she’d be battered by debris. She’d eat food if it was around, but wouldn’t bother stocking up if the cupboards were bare. S. M. had no fear of growing hungry.
She even lost the ability to recognize fear in the faces of those around her. S. M. could easily register happiness, confusion, or the sadness of friends and family, but didn’t have a clue when someone was scared or threatened. Worries, stress, and anxiety all dissolved along with her amygdalae.
One day, when S. M. was in her 40s, a man in a pickup truck pulled up and asked her to go on a date. She got in, and the man drove her to an abandoned barn, threw her on the ground, and tore off her clothes. Suddenly, a dog ran into the barn, and the man became nervous that people might be close behind. He zipped up his pants and dusted himself off. S. M. casually got up and followed the man back to his car. She asked to be driven home.
Dr. Justin Feinstein met S. M. in 2006 while getting a PhD in clinical neuropsychology at the University of Iowa. Feinstein specialized in anxieties, specifically in how to get over them. He knew that fear was the core of all anxieties: a fear of gaining weight led to anorexia; fear of crowds led to agoraphobia; fear of losing control led to panic attacks. Anxieties were an oversensitivity to perceived fear, be it spiders, the opposite sex, confined spaces, whatever. On a neuronal level, anxieties and phobias were caused by overreactive amygdalae.
Researchers had spent two decades studying S. M., trying to understand her condition, and trying to scare her. They showed S. M. films of humans eating excrement, took her to theme-park haunted houses, and put slithering snakes on her arms. Nothing worked.
Determined, Feinstein dug deeper and found a study in which human subjects were administered a single breath of carbon dioxide. Even with a small amount, patients reported feelings of suffocation, as if they’d been forced to hold their breath for several minutes. Their oxygen levels hadn’t changed and the subjects knew they were never in danger, but many still suffered debilitating panic attacks that lasted for minutes. This wasn’t a reaction to a perceived fear or an external threat; it wasn’t psychological. The gas was physically triggering some other mechanism in their brains and bodies.
Feinstein and a group of neurosurgeons, psychologists, and research assistants set up an experiment at a laboratory at the University of Iowa hospital. They brought S. M. in and sat her down at a desk, fitting an inhaler mask over her face, connected to an inhaler bag that contained a few lungfuls of 35 percent carbon dioxide and the rest room air. They explained to S. M. that the carbon dioxide would not damage her body, her tissues and brain would have plenty of oxygen. She would never be in any danger. Hearing this, S. M. looked the way she always looked: bored.
“We weren’t expecting anything to happen,” Feinstein told me. “Nobody was.” A few moments later, Feinstein released the carbon dioxide mix into the mouthpiece. S. M. inhaled.
Right away, her droopy eyes grew wider. Her shoulder muscles tensed, her breathing became labored. She grabbed at the desk. “Help me!” she yelled through the mouthpiece. S. M. lifted an arm and waved it as if she were drowning. “I can’t!” she screamed. “I can’t breathe!” A researcher yanked the mask off, but it didn’t help. S. M. jerked wildly and gasped. A minute or so later, she dropped her arms and returned to breathing slowly and calmly.
A single puff of carbon dioxide did to S. M. what no snakes, horror movies, or thunderstorms could. For the first time in 30 years, she’d felt fear, a full-fledged panic attack. Her amygdalae hadn’t grown back. Her brain was the same as it had always been. But some dormant switch had suddenly been flipped.
S. M. refused to inhale carbon dioxide again. Years later, the mere idea of it stressed her out. So Feinstein and his researchers confirmed the results with two German twins who also suffered from Urbach-Wiethe disease. The twins had lost their amygdalae, and neither had felt fear in a decade. A single inhalation of carbon dioxide quickly changed that when both suffered the same debilitating anxiety, panic, and crushing fear as S. M.
The textbooks were wrong. The amygdalae were not the only “alarm circuit of fear.” There was another, deeper circuit in our bodies that was generating perhaps a more powerful sense of danger than anything the amygdalae alone could muster. It was shared not only by S. M., the German twins, and the few dozen others with Urbach-Wiethe disease, but by everyone and almost every living thing—all people, animals, even insects and bacteria.
It was the deep fear and crushing anxiety that comes from the feeling of not being able to take another breath.
Take a sip of air through the nose or mouth. For this exercise, it doesn’t matter. Now hold it. In a few moments, you’ll feel a slight hunger for more. As this hunger mounts, the mind will race, the lungs will ache. You’ll become nervous, paranoid, and irritable. You’ll start to panic. All senses will zero in on that miserable, suffocating feeling, and your sole desire will be to take another breath.
The nagging need to breathe is activated from a cluster of neurons called the central chemoreceptors, located at the base of the brain stem. When we’re breathing too slowly and carbon dioxide levels rise, the central chemoreceptors monitor these changes and send alarm signals to the brain, telling our lungs to breathe faster and more deeply. When we’re breathing too quickly, these chemoreceptors direct the body to breathe more slowly to increase carbon dioxide levels. This is how our bodies determine how fast and often we breathe, not by the amount of oxygen, but by the level of carbon dioxide.
Chemoreception is one of the most fundamental functions of life. When the first aerobic life forms evolved two and a half billion years ago, they had to sense carbon dioxide to avoid it. The chemoreception that developed passed up through bacteria to more complex life. It’s what stimulates the suffocating feeling you just felt holding your breath.
As humans evolved, our chemoreception became more plastic, meaning it could flex and shift with changing environments. It’s this ability to adapt to different levels of carbon dioxide and oxygen that helped humans colonize altitudes 800 feet below and 16,000 feet above sea level.
Today, chemoreceptor flexibility is part of what distinguishes good athletes from great ones. It’s why some elite mountain climbers can summit Everest without supplemental oxygen, and why some freedivers can hold their breath underwater for ten minutes. All these people have trained their chemoreceptors to withstand extreme fluctuations in carbon dioxide without panic.
Physical limits are only half of it. Our mental health relies on chemoreceptor flexibility as well. S. M. and the German twins didn’t suffer from a debilitating panic attack and anxiety because of mental illness. They suffered because of a broken line of communication between their chemoreceptors and the rest of their brains.
This may sound very basic: of course we’re conditioned to panic when we’re denied a breath or think we’re about to be. But the scientific reason for that panic—that it can be generated by chemoreceptors and breathing instead of by external psychological threats processed by the amygdalae—is profound.
All this suggests that for the past hundred years psychologists may have been treating chronic fears, and all the anxieties that come with them, in the wrong way. Fears weren’t just a mental problem, and they couldn’t be treated by simply getting patients to think differently. Fears and anxiety had a physical manifestation, too. They could be generated from outside the amygdalae, from within a more ancient part of the reptilian brain.
Eighteen percent of Americans suffer from some form of anxiety or panic, with these numbers rising every year. Perhaps the best step in treating them, and hundreds of millions of others around the world, was by first conditioning the central chemoreceptors and the rest of the brain to become more flexible to carbon dioxide levels. By teaching anxious people the art of holding their breath.
As far back as the first century BCE, inhabitants of what is now India described a system of conscious apnea, which they claimed restored health and ensured long life. The Bhagavad Gita, a Hindu spiritual text written around 2,000 years ago, translated the breathing practice of pranayama to mean “trance induced by stopping all breathing.” A few centuries after that, Chinese scholars wrote several volumes detailing the art of breathholding. One text, A Book on Breath by the Master Great Nothing of Sung-Shan, offered this advice:
Lie down every day, pacify your mind, cut off thoughts and block the breath. Close your fists, inhale through your nose, and exhale through your mouth. Do not let the breathing be audible. Let it be most subtle and fine. When the breath is full, block it. The blocking (of the breath) will make the soles of your feet perspire. Count one hundred times “one and two.” After blocking the breath to the extreme, exhale it subtly. Inhale a little more and block (the breath) again. If (you feel) hot, exhale with “Ho.” If (you feel) cold, blow the breath out and exhale it with (the sound) “Ch’ui.” If you can breathe (like this) and count to one thousand (when blocking), then you will need neither grains nor medicine.
Today, breathholding is associated almost entirely with disease. “Don’t hold your breath,” the adage goes. Denying our bodies a consistent flow of oxygen, we’ve been told, is bad. For the most part, this is sound advice.
Sleep apnea, a form of chronic unconscious breathholding, is terribly damaging, as most of us know by now, causing or contributing to hypertension, neurological disorders, autoimmune diseases, and more. Breathholding during waking hours is injurious as well, and more widespread.
Up to 80 percent of office workers (according to one estimate) suffer from something called continuous partial attention. We’ll scan our email, write something down, check Twitter, and do it all over again, never really focusing on any specific task. In this state of perpetual distraction, breathing becomes shallow and erratic. Sometimes we won’t breathe at all for a half minute or longer. The problem is serious enough that the National Institutes of Health has enlisted several researchers, including Dr. David Anderson and Dr. Margaret Chesney, to study its effects over the past decades. Chesney told me that the habit, also known as “email apnea,” can contribute to the same maladies as sleep apnea.
How could modern science and ancient practices be so at odds?
Again, it comes down to will. The breathholding that occurs in sleep and constant partial attention is unconscious—it’s something that happens to our bodies, something that’s out of our control. The breathholding practiced by the ancients and revivalists is conscious. These are practices we will ourselves to do.
And when we do them properly, I’d heard they can work wonders.
It’s a muggy Wednesday morning and I’m sitting on a rumpled sofa in Justin Feinstein’s office at the Laureate Institute for Brain Research in downtown Tulsa, Oklahoma. Across from me is a window that looks out over a cardboard-colored sky and a paisley landscape of red and orange leaves. Feinstein is seated below it, flipping through a stack of scientific papers on a doublewide desk that has not one inch of vacant space. He’s wearing an untucked button-down shirt with the cuffs rolled up, flip-flops, and baggy khakis with crayon stains, compliments of his three-year-old daughter. He looks the way you’d imagine a neuropsychologist to look: brainy with a touch of funk.
Feinstein has just been awarded a five-year NIH grant to test the use of inhaled carbon dioxide on patients with panic and anxiety disorders. After his experience administering the gas to S. M. and the German twins with Urbach-Wiethe disease, he’d become convinced carbon dioxide could not only cause panic and anxiety, but that it might also help cure it. He believed that breathing heavy doses of carbon dioxide might elicit the same physical and psychological benefits as the thousand-year-old breathholding techniques.
But his therapy didn’t require patients to actually hold their breath or block their throats and count to one hundred with clenched hands like the ancient Chinese. His patients were far too anxious and impatient to practice such an intense technique. Carbon dioxide did all that for them. They’d come in, think about whatever they wanted to think about, take a few inhales of the gas, flex their chemoreceptors back to normal, and be on their way. It was the ancient art of breathholding for those people too anxious to hold their breath.
Breathholding hacks, or, as Feinstein would call them, carbon dioxide therapies, have been around for thousands of years. The ancient Romans prescribed soaking in thermal baths (which contained high levels of carbon dioxide that was absorbed through the skin) as a cure for anything from gout to war wounds. Centuries later, Belle Époque French gathered at thermal springs at Royat in the French Alps to wade in bubbling waters for days at a time.
“The study of the chemical composition of the four mineral springs at Royat will show that we have several powerful agents at our command, and that much is available for the treatment of many morbid conditions, which resist the usual pharmaceutical applications we make use of in daily practice,” wrote George Henry Brandt, a British doctor who visited in the late 1870s. Brandt was talking about skin disorders like eczema and psoriasis, along with respiratory maladies like asthma and bronchitis, all of which were “cured almost with certainty” after a few sessions.*
Royat physicians would eventually bottle up carbon dioxide and administer it as an inhalant. The therapy was so effective that it made it stateside in the early 1900s. A mixture of 5 percent carbon dioxide and the rest oxygen made popular by Yale physiologist Yandell Henderson was used with great success to treat strokes, pneumonia, asthma, and asphyxia in newborn babies. Fire departments in New York, Chicago, and other major cities installed carbon dioxide tanks on their trucks. The gas was credited with saving many lives.
All the while, blends of 30 percent carbon dioxide and 70 percent oxygen became a go-to treatment for anxiety, epilepsy, and even schizophrenia. With a few huffs of the stuff, patients who’d spent months or years in a catatonic state would suddenly come to. They’d open their eyes, look around, and begin calmly talking with doctors and other patients.
“It was a wonderful feeling. It was marvelous. I felt very light and didn’t know where I was,” one patient reported. “I knew something had happened to me and I wasn’t sure what it was.”
The patients would stay in this coherent, lucid state for about 30 minutes, until the carbon dioxide wore off. Then, without warning, they’d stop mid-sentence and freeze, staring into space and striking statue-like poses or sometimes collapsing. The patients were sick again. They’d stay that way until the next hit of carbon dioxide.
And then, for reasons nobody quite understands, by the 1950s, a century of scientific research disappeared. Those with skin disorders turned to pills and creams; those with asthma managed symptoms with steroids and bronchodilators. Patients with severe mental disorders were given sedatives.
The drugs never cured schizophrenia or other psychoses, but they didn’t provoke out-of-body experiences or feelings of euphoria, either. They numbed patients, and continued to numb them for weeks, months, and years—as long as they kept taking them.
“What’s interesting to me is that nobody disproved it,” says Feinstein of carbon dioxide therapy. “The data, the science, still holds today.”
He tells me how he’d stumbled upon some obscure studies by Joseph Wolpe, a renowned psychiatrist who rediscovered carbon dioxide therapy as a treatment for anxiety and had written an influential paper about it in the 1980s. Wolpe’s patients shared stunning and long-lasting improvements after just a few huffs. Donald Klein, another renowned psychiatrist and expert in panic and anxiety, suggested years later that the gas might help reset the chemoreceptors in the brain, allowing patients to breathe normally so they could think normally. Since then, few researchers have studied the treatments. (Feinstein estimates there are about five researching it now.) He just kept wondering if the early researchers were right, if this ancient gas might be a remedy to modern ailments.
“As a psychologist, I think, what are my options, what is the best treatment for these patients?” Feinstein says.
Pills, he tells me, offer a false promise and do little good for most people. Anxiety disorders and depression are the most common mental illnesses in the United States, and about half of us will suffer from one or the other in our lifetime. To help cope, 13 percent of us over the age of 12 will use antidepressants, most often selective serotonin reuptake inhibitors, also known as SSRIs. These drugs have been lifesavers for millions, especially those with severe depression and other serious conditions. But less than half the patients who take them get any benefits.* “I keep asking myself,” says Feinstein, “Is this the best we can do?”
Feinstein had explored various non-pharmaceutical therapies; he’d spent a decade learning and teaching mindfulness meditation. A wealth of scientific research shows that meditation can change the structure and function of critical areas of the brain, help relieve anxieties, and boost focus and compassion. It can work wonders, but few of us will ever reap these rewards, because the vast majority of people who try to meditate will give up and move on. For those with chronic anxieties, the percentages are far worse. “Mindful meditation—as it is typically practiced—is just no longer conducive to the new world we live in,” Feinstein explains.
Another option, exposure therapy, is a technique that exposes patients repeatedly to their fears so that they become more accepting of them. It’s highly effective but takes a while, usually involving many long sessions over weeks or months. Finding psychologists with that kind of time, and patients with the necessary resources, can be a challenge.
But everyone breathes, and, today, few of us breathe well. Those with the worst anxieties consistently suffer from the worst breathing habits.
People with anorexia or panic or obsessive-compulsive disorders consistently have low carbon dioxide levels and a much greater fear of holding their breath. To avoid another attack, they breathe far too much and eventually become hypersensitized to carbon dioxide and panic if they sense a rise in this gas. They are anxious because they’re overbreathing, overbreathing because they’re anxious.
Feinstein found some inspiring recent studies by Alicia Meuret, the Southern Methodist University psychologist who helped her patients blunt asthma attacks by slowing their breathing to increase their carbon dioxide. This technique worked for panic attacks, too.
In a randomized controlled trial, she and a group of researchers gave 20 panic sufferers capnometers, which recorded the amount of carbon dioxide in their breath throughout the day. Meuret crunched the data and found that panic, like asthma, is usually preceded by an increase in breathing volume and rate and a decrease in carbon dioxide. To stop the attack before it struck, subjects breathed slower and less, increasing their carbon dioxide. This simple and free technique reversed dizziness, shortness of breath, and feelings of suffocation. It could effectively cure a panic attack before the attack came on. “‘Take a deep breath’ is not a helpful instruction,” Meuret wrote. Hold your breath is much better.
We leave Feinstein’s office and stroll through a labyrinth of elevators and staircases until we enter through soundproofed double doors. This is Feinstein’s lair. Through the door to the right, he and his team conduct research on floatation, a therapy that involves lying in a salt-water pool in a dark, soundless room. Through the door to the left is Feinstein’s newest project: a carbon dioxide therapy laboratory. It’s a tiny windowless box that looks as if it might have held HVAC equipment at one point. We squeeze into the space like clowns in a phone booth. On a folding desk is the usual array of monitors, computers, wires, EKGs, capnometers, and other stuff I’ve grown accustomed to wearing over the past few years. A beat-up yellow cylinder that looks like a Cold War–era Russian missile sits in the corner. Feinstein tells me it holds 75 pounds of pure carbon dioxide.
For the past few months, as part as his NIH research, Feinstein has brought in patients suffering with anxiety and panic to this lab and given them a few hits of carbon dioxide. So far, he tells me, the results have been promising. Sure, the gas elicited a panic attack in most patients, but this is all part of the baptism-by-fire process. After that initial bout of discomfort, many patients report feeling relaxed for hours, even days.
I’ve decided to throw my chemoreceptors into the ring. I’ve signed up to see what a few heavy doses of carbon dioxide would do to my own body and brain.
Feinstein sticks a piece of white foamy material with a metal sensor on my middle and ring fingers. This device, called a galvanic skin conductance meter, will measure small amounts of sweat released during states of sympathetic stress. On my other hand, a pulse oximeter will record my heart rate and oxygen levels.
The mixture I’ll inhale is 35 percent carbon dioxide, and the rest is room air—about the same percentage of carbon dioxide once used to test schizophrenics, sans the oxygen. Feinstein administered this same dose on S. M., who panicked and hated it. He also tried it out on a few patients early on, but they too suffered heavy panic attacks. Some patients were so freaked out they refused to take another hit, so Feinstein now reduces the dose to 15 percent—enough to give the chemoreceptors a good workout, but not enough to keep patients from coming back for more. Since I didn’t suffer from panic attacks or chronic anxiety, not yet at least, he offered to crank up my dose to the S. M. level to see what happens.
He calmly explains, for the third time today, that any suffocation I might feel after inhaling the gas is only an illusion, that my oxygen levels will remain unchanged, and that I’ll be in no danger. Although he means to calm my fears, the constant disclaimers only make me more, well, anxious.
“You good?” Feinstein says, tightening the Velcro straps on the face mask. I nod, take a few last, sweet inhales of room air, and sink deeper in the chair. We’ll begin takeoff in two minutes.
As Feinstein walks over to a computer and futzes with cables and tubes and wires, I’m left to sit, stare at my cuticles, and reminisce a bit. My mind wanders to last year, when I first visited Anders Olsson in Stockholm.
It was just after our interview in the co-working reception hall, and Olsson took me into his office, a little hovel filled with research papers, pamphlets, and face masks. A beat-up carbon dioxide tank stood amid the rubble. Olsson told me that he and a group of DIY pulmonauts had been running their own experiments with carbon dioxide over the past couple of years. They weren’t interested in the megadoses used to treat epilepsy and mental disorders. Olsson and his crew weren’t sick. They were interested in exploring the preventative and performance benefits of the gas, in flexing their chemoreceptors even wider so that they could push their bodies further.
The most effective and safest blend they found was a few huffs of around 7 percent carbon dioxide mixed with room air. This was the “super endurance” level Buteyko found in the exhaled breath of top athletes. Breathing in this mixture had none of the hallucinogenic or panic-inducing effects. You hardly noticed it, and yet it offered potent results. Olsson shared some reports from pulmonauts in the field.
User #1: “So I’m in Toronto now and I decided to go for a rollerblade. I’m a big rollerblader and have done this route by the water on lakeshore many times before. But get this: No matter [how] hard I pushed it, and I pretty much gave it 110% the entire time . . . I not once needed to open my mouth to pant!”
User #2: “I did some carbon dioxide treatments 3 times yesterday, about 15 minutes a piece. And today, I went canoeing and then when I had sex with my girlfriend . . . by the end of it she was panting and tired, and I wasn’t even out of breath at all! I felt like I was superhuman!”
User #3: “Holy fuck! . . . I was breathing . . . and I started to feel fricking AMAZing. Euphoric even. To the point where breathing felt automatic.”
Olsson hooked up the tank and offered me a few huffs. I felt a slight spaciness, which was soon followed by a slight headache. I was unimpressed.
Back in Tulsa, Feinstein is about to administer something else entirely. It’s several times what I’d had before and several thousand times more than my chemoreceptors are normally exposed to.
He reaches over and points to the big red button on the desk. It switches the air hose from room air to the carbon dioxide in a foil bag hanging on the wall. The bag is a precautionary device. I’ll be huffing from it instead of directly out of the tank, in case there’s a malfunction in the system, or in my brain. Should a faucet stay open or should I suddenly start panicking uncontrollably, I’ll only be able to breathe the contents inside the bag, which works out to about three big huffs.
Next to the red button is a stress dial. It will record my perceived anxiety. It’s currently set to 1, the lowest level. When I start feeling anxious after inhaling the gas, I can crank the dial as far up as 20, marking an extreme state of panic.
Over the next 20 minutes, I’ll need to take three big inhales of carbon dioxide. I can take all three breaths one after the other if I’m feeling comfortable. If I’m not, I can wait several minutes between hits. The amount of time patients wait provides insight into how intense the experience was.
Strapped in and ready, I’m trying to calm myself, watching the live feed of my vitals on the computer monitor. As I inhale, my heart rate increases, then decreases with every exhale, making a smooth sine wave across the screen. Oxygen hovers at around 98 percent, and exhaled carbon dioxide holds steady at 5.5 percent. All systems are go.
It feels like I’m a fighter pilot on a stealth mission, hissing Darth Vader breaths through a face mask, my hand on a missile-release button. Not the kind of scene I’d ever associated with mental health therapy. But Feinstein’s goal isn’t to change the way a patient feels on an emotional level. It’s to reset the basic mechanics of the primitive brain.
Chemoreceptors, after all, don’t care if the carbon dioxide in the bloodstream is generated from strangulation, drowning, panic, or a foil bag on a wall in Tulsa. They set off the same alarm bells. Experiencing such an attack in a controlled environment helps demystify it, teaching patients what an attack feels like before it comes on so we can prevent it. It gives us conscious power over what for too long has been considered an unconscious ailment, and shows us that many of the symptoms we’re suffering can be caused, and controlled, by breathing.
One more slow and deep inhale, a thumbs-up, and I close my eyes and push all the air from my lungs. I punch the red button and hear the hose engage to the foil bag, then take in an enormous breath.
The air tastes metallic. It oozes into my mouth, zinging my tongue and gums with the sensation of drinking orange juice from an aluminum cup. The gas pushes deeper, down my throat, coating my innards with what feels like a sheet of aluminum foil. It cracks through the bronchioles, into the alveoli, and into the bloodstream. I brace myself for the hit.
One second. Two seconds. Three. Nothing. I feel no different than I did a few seconds ago or a few minutes before that. I hold the stress dial at 1.
Feinstein said this might happen. He’d given this heavy dose to a Wim Hof practitioner months earlier, and the man barely felt anything. After so much heavy breathing and breathholding, Feinstein hypothesized this subject had already flexed his chemoreceptors wide open. Meanwhile, I had just come off ten days of forced mouthbreathing followed by ten days of forced nasal breathing. I’d raised my resting carbon dioxide levels by 20 percent. I too have probably flexed my chemoreceptors as far as they could reasonably go.
Amid these thoughts, I feel a slight constriction in my throat. It’s subtle. I take in a breath of room air, push out an exhale. This requires some effort. The red button is switched off; I’m no longer breathing any more of the carbon dioxide mixture, but it feels like someone has jammed a sock in my mouth. I try to take another breath, but the sock keeps growing.
OK, now there’s a pounding in my temples. I open my eyes to check my levels, but the room is blurry. A few seconds later, I’m viewing the world through what looks like cracked and dirty binoculars. I can’t breathe. Every sense feels as if it’s being torn from my control, vacuumed out.
Maybe 10 or 20 seconds pass before the sock shrinks, there’s a cooling at the back of my neck, and the whirlpool of anxiety reverses and floats off. The color and clarity of my vision ripples outward, like a hand clearing mist from a window. Feinstein stands a few feet from me, staring. It all comes back to life. I can breathe again.
I sit there for a few minutes sweating, kind of laughing, kind of crying. I’m trying to prepare myself for two more inhales of this ghastly mixture of gas over the next 15 minutes. Any self-talk I can muster—This choking is just an illusion; relax, it will only last a few minutes—does nothing.
After all, the fear I had just felt and would feel again with the next hit won’t be mental. It’s mechanical; and conditioning the chemoreceptors to widen takes a few sessions, which is why Feinstein’s patients come back to re-up over the course of a few days. This is, at its core, an exposure therapy. The more I expose myself to this gas, the more resilient I’ll be when I’m overloaded.
And so, in the name of research, and for the sake of my own future chemoreceptor flexibility, I push the red button and take two more hits, one after the other.
And I panic, again and again.