Authored by a science journalist for a lay audience, ‘Breath’ covers the ‘lost art’ of using inhalations and exhalations to improve health.

By Sree Roy

Sleep medicine professionals are experts on the nuances of breath. The subspecialty has a keen understanding of the havoc that disordered breathing can wreak on a patient’s health and well-being. Scientist journalist James Nestor is also fascinated by the connections between breath and health, and his new book Breath: The New Science of a Lost Art has been met with both enthusiasm and skepticism from the sleep medicine community.

A New York Times Bestseller and Washington Post Notable Nonfiction Book of 2020, Breath is accessible and entertaining. Nestor’s sources include a few sleep medicine and pulmonology professionals but more frequently are “pulmonauts,” a category he describes as “tinkerers…who stumbled on the powers of breathing because nothing else could help them.”

In researching the topic, Nestor subjects himself to all manner of breathing experiments—at his own financial (and in some cases, health) expense. One involves having otolaryngologist Jayakar V. Nayak, MD, PhD, physically obstruct his nose, effectively forcing Nestor to breathe only through his mouth for 10 days.

During Nestor’s first night of nasal-obstructed sleep, he records a fourfold increase in sleep apnea events and a 1,300% increase in snoring. Over the course of 10 days, Nestor also develops insomnia. His blood pressure and pulse increase, and his body temperature decreases. His mental clarity, he says, “hit rock bottom.”

After the nose plugs are removed, Nestor focuses on breathing through only his nose—“all day and all night”—as well as practicing yoga and other ancestral-inspired nasal breathing techniques (such as alternate nostril breathing) in a bid to improve his overall health. After 10 days of nasal breathing, Nestor’s health maladies have reversed. Now, his snoring time has decreased by 4,000%, his sleep apnea events are nil, and his blood pressure an average of 10 points lower. He no longer has insomnia or wakes up in the middle of the night to use the bathroom.

“My experiment is not conclusive evidence of anything. But it was piggy-backing on years of studies,” Nestor says in a phone interview.

Peer-reviewed studies are important to Nestor. “It’s important to look at the references,” he says. “I knew people weren’t going to believe these things.” So Nestor published about 500 scientific references for free on his website,, where he also posts breathing videos and expert Q&As.

But the book also makes the astute reader realize that there aren’t enough peer-reviewed studies on most do-it-yourself breathing exercises. For example, Nestor shares his anecdotal experience with mouth-taping during sleep and says it works well for him. But mouth-taping is also one of the most controversial concepts in sleep medicine. Indeed, Nestor says that mouth breathing can be the cause of sleep apnea, and some (Nestor’s emphasis) people could be cured by taping their mouths closed during sleep.

“Sleep apnea can occur in different parts of the airway. I’m not here to prescribe a blanket cure for everyone,” Nestor says.

“I’m not going to say everyone who mouth breathes is going to suffer from snoring or sleep apnea or everyone who switches from mouth to nose breathing will see them go away. But there are links between mouth-breathing and the prevalence of snoring and sleep apnea, and that is very clear. It’s no coincidence that for some people who use a little bit of mouth tape at night—if they find a way to breathe through their nose at night—their snoring is noticeably reduced and in some cases their sleep apnea can be reduced.” He says he has received “dozens of emails” saying tape has resolved readers’ sleep apnea. “It’s not a placebo effect,” he says.

There are a few studies that support Nestor’s assertion. One paper about 30 patients with mild obstructive sleep apnea found that, on average, the apnea-hypopnea index decreased from 12.0 to 7.8 events per hour with mouth-taping during sleep.1

But sleep medicine professionals raise concerns that mouth-taping is being encouraged in a book that people with sleep-disordered breathing may be reading. Will people with suspected sleep apnea “cure” themselves, so as to avoid undergoing a medical sleep study? Will someone who tries mouth-taping vomit and aspirate?

For his part, Nestor readily acknowledges that CPAP for sleep apnea is a lifesaver. “It’s not a ‘this versus that,’” he says. “CPAP has saved innumerable lives.”

Nestor also addresses the hot-button issue of whether many insomnia cases are actually overlooked sleep-disordered breathing.

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“In my opinion, poor sleep is mostly tied to a physical disturbance in our ability to breathe,” Nestor says. “In my view, based on so many interviews, you have to figure out the breathing problem first. Once you get that out of the way, if someone is still suffering from insomnia, you can address any psychological issues.”

He also proclaims, “No amount of snoring is normal.” Citing the works of sleep physician Christian Guilleminault, MD, and others, Nestor believes that “snoring can have the same downstream effects of sleep apnea.” He says upper airway resistance syndrome is a real problem that should be addressed as diligently by sleep physicians as sleep apnea is. “There are clear links between snoring and neurological problems, hormonal imbalances, and so on and so forth,” Nestor says. “Christian Guilleminault…found you don’t even need to snore to suffer. Any resistance in the airway can cause so many problems.”2,3

In response to a question about why a professional home sleep test device wasn’t used to gather data during his breathing experiments, Nestor points out that he purchased a wide assortment of technology that’s available to consumers without a prescription, including pulse oximeters, night vision cameras, and smart phone apps. But he would love to see scientists—including sleep medicine researchers—using medical-grade technology to test the recommendations he puts forth in Breath. Nestor encourages scientists to reach out to him via his site, as he is willing to help make connections to facilitate such research. “I would really hope someone in this community who has access to real resources and the top technology would do that,” he says.

Sree Roy is editor of Sleep Review.


  1. Huang T-W, Young T-H. Novel porous oral patches for patients with mild obstructive sleep apnea and mouth breathing: a pilot study. Otolaryngol Head Neck Surg. 2015;152(2):369-73.
  2. Guilleminault C, Lee JH. Does benign “primary snoring” ever exist in children? Chest. 2004 Nov;126(5):1396-8.
  3. Guilleminault C, Lee JH, Chan A. Pediatric obstructive sleep apnea syndrome. Arch Pediatr Adolesc Med. 2005 Aug;159(8):775-85.