Getting your Trinity Audio player ready...
Is taping your mouth shut before sleep the key to better rest? In his book "Breath: The New Science of a Lost Art", James Nestor explores the science and practice of proper breathing. According to him, humans are the worst breathers in the animal kingdom, suffering from what he describes as a "silent epidemic" of poor breathing. Most people breathe through their mouths instead of their noses, which leads to a host of health issues.
Nestor claims that switching to nasal breathing has significant health benefits. The idea behind sealing the mouth is simple: by blocking the option to breathe through the mouth, nasal breathing is encouraged.
Throughout the past century, Western medicine largely regarded the nose as a secondary organ. The prevailing view was that it’s nice to breathe through it if possible, but if not, no big deal—that’s what the mouth is for.
Many doctors, researchers, and scientists still hold this view. For instance, the U.S. National Institutes of Health has 27 departments dedicated to studying the lungs, eyes, skin, ears, and more, but none devoted to the nose or sinuses.
Even Nestor himself once thought that stuffy noses, snoring, mild wheezing, asthma, allergies, and similar issues were normal parts of being human. But his perspective changed when he found himself in the basement of the Museum of Archaeology and Anthropology at the University of Pennsylvania. There, he met Dr. Mariana Evans, an orthodontist and dental researcher who spent years examining human skulls, both ancient and modern.
In the famous collection of skulls belonging to Samuel Morton, a 19th-century scientist known for his racist studies attempting to prove the "superiority of the white race," Evans discovered something surprising. Instead of endorsing Morton’s theories, the skulls revealed evidence of an ideal facial structure lost to modern humanity.
The skulls, which date back anywhere from 200 years to thousands of years, display consistent traits across all cultures: large, forward-facing jaws, wide sinus cavities, and broad mouths. Most strikingly, despite the fact that none of our ancestors brushed their teeth or visited dentists, their teeth were perfectly straight.
This ancient facial structure created wide airways that prevented modern respiratory problems like snoring, sleep apnea, and sinusitis. Physically, it was nearly impossible for anything to obstruct these wide airways.
In comparison, researchers found that modern skulls exhibit an entirely different growth pattern: receding chins, jaws that have shifted backward, and shrunken sinus cavities. Almost all modern skulls show some degree of crooked teeth.
The most alarming discovery is that out of roughly 5,400 mammalian species on Earth, humans are the only species to routinely suffer from jaw misalignments and malocclusions (bad bites).
What caused this dramatic shift in facial structure?
Why have respiratory problems and jaw misalignments become so prevalent in the modern era? Evans posed a critical question: "Why would we evolve in a way that makes us sick?" As she placed a Persian skull back into storage and picked up another labeled "Sakar," she noted its perfect facial structure, which was a stark contrast to the others. "This is what we’re trying to figure out," she said.
Evolution doesn’t always mean progress, Evans explained. It means change—and that change can be for better or worse. Today, the human body is changing in ways that have little to do with "survival of the fittest." Instead, we are developing traits that harm our health, passing them on to future generations. This concept, known as "disevolution," has gained traction thanks to Harvard biologist Daniel Lieberman. Disevolution explains why we suffer from back and foot pain, why our bones are becoming more brittle, and why we breathe so poorly.
Around 12,000 years ago, humans in Southwest Asia and the Fertile Crescent of the Middle East stopped foraging for roots and wild vegetables and hunting game, as they had for hundreds of thousands of years. Instead, they began cultivating their own food. These were the first agricultural societies, and it was within these primitive communities that humans first experienced widespread cases of crooked teeth and distorted jaws.
Initially, this wasn’t a universal problem. While one farming community might suffer from facial deformities, another community just 60 miles away might remain unaffected. Crooked teeth and the accompanying respiratory issues seemed to be entirely random.
But 300 years ago, these ailments went viral. Suddenly, a large portion of the global population began to suffer from these issues. Mouths shrank, faces flattened, and sinuses became clogged.
The morphological changes that had occurred in the human head up to that point—such as the lowering of the voice box that restricted our throats or the expansion of the brain that lengthened our faces—were minor compared to this sudden shift. Our ancestors adapted reasonably well to those gradual changes.
However, the changes brought about by the rapid industrialization of agricultural food were far more harmful. Within just a few generations of eating processed agricultural foods, modern humans became the worst breathers in the history of Homo sapiens—and the worst breathers in the entire animal kingdom.
Nestor’s experiment
Nestor begins his book with a grueling experiment that left him exhausted and miserable: he gave up nasal breathing for ten days.
The experiment, conducted under the supervision of the Stanford Rhinology Research Institute, consisted of two phases. In the first phase, Nestor’s nose was blocked, and he was forced to live his daily life breathing only through his mouth. He had to eat, exercise, and sleep as usual, relying solely on mouth breathing. In the second phase, he switched his breathing to nasal only, eating, drinking, exercising, and sleeping like before but incorporating specific breathing techniques throughout the day.
What followed was a deep dive into the science of breathing, exploring the transformative potential of something as simple as how we take in air. Nestor’s findings challenge long-held assumptions about human health, offering a powerful argument for rediscovering the lost art of proper breathing.
Between each stage, we returned to Stanford for tests: gas levels, signs of inflammation, hormone levels, odor, rhinometry, lung function, and more. The researcher, Dr. Jayakar Nayak, compared the datasets to determine what, if anything, changed in our bodies and minds as our breathing patterns shifted.
My friends showered me with gasps of astonishment when I told them about the experiment. "Don’t do it!" warned a few yoga enthusiasts. But most people just shrugged. "I haven’t breathed through my nose in ten years," said a friend who has suffered from allergies his entire life. Others said variations of:
"What's the big deal? Breathing is breathing."
Is it though?
Months after the Stanford experiment ended, Dr. Jayakar Nayak sent an email with the results of the 20-day study. The core conclusion was already clear: mouth breathing is terrible.
After just 240 hours of exclusively breathing through the mouth, catecholamine levels and stress hormones skyrocketed, indicating the body was under both physical and mental stress. A bacterial infection—Corynebacterium diphtheriae—was found in the nasal passages. Had the participant continued mouth breathing for just a few more days, it likely would have developed into a full-blown sinus infection. Simultaneously, his blood pressure soared, and his heart rate variability dropped. The other participant’s data was similar.
At night, the constant flow of unfiltered air through his open mouth caused such a collapse of soft tissues in his throat that he began experiencing persistent choking during sleep. He snored. Within days, he started choking involuntarily and suffered from sleep apnea episodes. Had he continued, he likely would have developed chronic snoring and obstructive sleep apnea, along with its associated problems: hyperventilation, metabolic disorders, and cognitive issues.
Not all metrics changed. Blood sugar levels were unaffected. Blood counts and calcium levels remained stable, as did most other blood markers.
There were a few surprises. His lactate levels—a marker of anaerobic respiration—actually decreased with mouth breathing, suggesting he was burning more oxygen-consuming aerobic energy. This was contrary to what most fitness experts would predict (the other participant’s lactate levels increased slightly). He lost about one kilogram of weight, likely due to water loss from exhaling. But don’t count on a "mouth-breathing diet" after the holidays.
The fatigue, irritability, anxiety, and constant trips to the bathroom… The terrible breathing, the sensory dullness, and the abdominal pain—it was awful.
There’s a reason the human body evolved to breathe through two channels. It increases survival chances. If the nose is blocked, the mouth acts as a backup ventilation system. The temporary mouth breathing we do before Steph Curry sinks a basket, a sick child exhales during a fever, or when we laugh with friends doesn’t have lasting health effects.
Chronic mouth breathing, however, is a different story. The body is not designed to process raw air for hours on end, day or night. There is nothing normal about it.
The day Nestor removed the plugs and tape from his nose, his blood pressure plummeted, carbon dioxide levels rose, and his heart rate returned to normal. Snoring reduced significantly compared to the mouth-breathing phase, dropping from several hours a night to just a few minutes. Within two days, none of us snored at all. The bacterial infection in his nose resolved quickly without treatment. The body healed itself simply by breathing through the nose.
Anne Kearney, a speech pathology doctor at Stanford’s Voice and Swallowing Center, was so impressed by our data and the transformation she experienced when overcoming nasal congestion and mouth breathing that, as of this writing, she’s planning a study involving 500 participants to examine the effects of sleep strips on snoring and sleep apnea.
Kearney herself had lived for years as a mouth breather due to chronic nasal congestion. When she consulted with an ENT specialist, she discovered her nasal passages were blocked by tissue. The doctor insisted surgery or medication was the only way to open her nasal cavities. Instead, she chose to seal her mouth shut using sleep tape.
"On the first night, I lasted five minutes before ripping it off," she told Nestor. On the second night, she managed ten minutes. A few nights later, she slept with it on all night. Within six weeks, her nasal passages opened.
"This is a classic case of 'use it or lose it,'" Kearney said. To prove her point, she examined the nasal passages of 50 patients who had undergone laryngectomy surgery, a procedure that creates a breathing hole in the throat. Within two months to two years, every one of them suffered complete nasal blockage.
Like other parts of the body, the nasal passages respond to the stimuli they encounter. When the nose is deprived of regular use, it atrophies. This was Kearney’s experience, as well as that of her patients and countless others in the general population. The next step is often snoring and sleep apnea.
On the other hand, regular use of the nose trains the tissues in the nasal passages and throat to contract and stay open. Kearney and many of her patients healed themselves this way—by breathing through the nose, all day and all night.
The question of how to seal the mouth with sleep tape, or "sleep strips," as they’re called, is a matter of personal preference. Everyone Nestor spoke to had a unique technique. The internet is full of suggestions. One person uses eight pieces of 1 inch-wide medical tape to create a sort of beard. Another uses duct tape. One woman suggested taping the entire lower half of the face.
Get the Ynetnews app on your smartphone: Google Play: https://bit.ly/4eJ37pE | Apple App Store: https://bit.ly/3ZL7iNv
Nestor himself conducted his own experiments over several days, using blue painter’s tape (which had a strange smell) and duct tape (which crinkled and made noise). Band-Aids were too sticky.
Ultimately, he realized he only needed a small piece of tape about the size of a postage stamp placed in the middle of the lips—like a Charlie Chaplin mustache shifted two centimeters downward. That’s it. This method was less claustrophobic and left small gaps on either side of his mouth in case he needed to cough or speak.
Within three nights of using this small piece of tape, his snoring reduced from four hours to just ten minutes a night. With the disappearance of snoring came the end of sleep apnea.
Finally, he slept well.