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BOOKCLUB: Breath, by James Nestor

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At some point, I became aware that the main benefit I received from yoga was the breathing. The Ujayiithe champion’s breath – is my favorite. I do it most of the day, especially when working on tasks. I’ve wondered if this is the most important thing I’ve learned in my practice. James Nestor seems to have had a similar question as is evident by his 2020 offering Breath: The New Science of a Lost Art. The book was NPR’s Book of the Year1 and notes Nestor’s journey to discover how breathing impacts our health and well-being. What he discovered is beautiful, terrifying, and all too useful.

Nestor’s Experiment

In the book, Nestor explains how he had a doctor plug his nose with silicone forcing him to breathe only through his mouth for ten days. There were ethical concerns with the experiment and so Nestor both conducted and funded the experiment himself having just one other participant. He recorded several items influenced by mouth-only breathing. His blood pressure skyrocketed, and he began to snore and experience sleep apnea. The quality of sleep was dramatically affected. He experienced dry mouth and felt physically drained.

Nestor reported that recovery after workouts was terrible. The experience was reportedly far worse than he expected. He experienced extreme irritability and anxiety. Nestor questioned his reasons for doing the experiment before the end. Towards the end, Nestor began to get a serious sinus infection caused by the blocked nasal passageways.

The second part of the experiment involved breathing only through the nose. An experience much more pleasant than the first.

Humans Are Terrible Breathers

It is speculated that 25-50% of the population breathes only through the mouth. Sixty to seventy percent of the population mouth-breath while sleeping.

Especially early in life, mouth-breathing impacts the structure of the face. Mouth breathing can cause an elongation of the face, crooked teeth, and swelling of the tonsils. It is speculated that this issue may be predominantly caused by our modern eating of ever softer foods. Ancient human skulls support this theory due to their proportion of mouth-to-face size and straight teeth. Humans are the only animals in the animal kingdom to have misaligned jaws and crooked teeth.

Along with softening food, this phenomenon is due to the enlargement of our brains. The development of the brain is put in higher priority than our ability to breathe.

Benefits of Nasal Breathing

The nose filters, cleans, heats, and moistens the air allowing us to absorb 20% more oxygen than when inhaling through the mouth. The nose plays a role in erectile dysfunction, triggering hormones and neurochemicals lowering blood pressure. The nose can ease digestion, react to a woman’s menstrual cycle, regulate heart rate, store memories, and control blood vessel dilation.

The nose is more connected to the genitals than any other organ. The right nostril appears to be an accelerant. Breathing through the right nostril increases circulation and body temperature rises in activation of the sympathetic nervous system – fight or flight. The right nostril will increase blood flow to the left side of the brain, increasing the ability to solve problems, conduct logic, and perceive language. The left nostril is a decelerant working opposite the right nostril. This nostril activates the parasympathetic nervous system causing rest, relaxation, and digestion. The blood flow is increased in the right hemisphere impacting abstract thought, creativity, and negative emotion.

Nasal breathing causes the sinuses to release nitric oxide, dilating and flushing the blood vessels resulting in more oxygen getting to cells.

Typically when there is nasal blockage it is possible to train your nasal passageways to allow more air to pass through. Nasal dilators are sometimes helpful in this retraining of nasal airways.

Nasal breathing during sleep causes the body to release vasopressin, a hormone that regulates kidney function. This will prevent waking up late at night to urinate and further, will help prevent losing too much water causing dehydration while sleeping.

Many doctors have their patients tape their mouths shut while sleeping in order to force nasal breathing in a practice called “mouth taping”.

Nasal breathing while exercising can actually lessen the number of breaths necessary during extreme physical activity. One study highlighted an athlete going from 47 mouth breaths to 14 nasal breaths while maintaining the same heart rate. The participants reported feeling invigorated while nasal breathing and exhausted while mouth breathing.


Critics of Nestor’s book warn that “mouth taping” is riskier than reported. There is some chance of suffocation. And even though it is mentioned in the book, nasal breathing is not always a cure for sleep apnea as is sometimes reported by those citing or reading the book.2

Other criticism points out that the conclusions that he draws are a bit beyond what the research may point towards. The “experiment”, though backed by scientific data remains almost an “n of one” study.

My Take

Simply said, focusing on breathing and realizing the power of nasal breathing can have an enormous impact on well-being. I have spent a lot of time in the past six months doing yoga and working with nasal breathing. I’ve noticed a big difference in my well-being. Specifically, I ran two half marathons both at PR paces. I considered what happened as I did not focus on training as much as I had in the past. I believe what made the difference was increased lung capacity and nasal breathing during the races. This idea actually led me to this book. My experience is very similar to that of Nestor’s.

What’s your experience with nasal breathing?


  2. Nestor, J., 2020. Breath: The New Science of a Lost Art. 1st ed. Riverhead Books.

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