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How (not) to breathe

How (not) to breathe

Breath: Book review & Reflections

I recently finished reading Breath: A New Science of a Lost Art by James Nestor. As someone who breathes through their mouth when they sleep, I’d seen a few recommendations of the book and finally got round to reading it — I was not disappointed!

With my scientist hat on, I was very skeptical when I started reading. Sure, we know the importance of breath on our health and it’s impact on our nervous system. Breathing exercises are commonly recommended to reduce stress, anxiety, improve mood and sleep and in yoga we practice pranayama to energise, calm or balance ourselves — none of this is new! However, the book explored many things I’d never even considered about breath, and there were a few key points that stood out. The difference between breathing through the nose and the mouth and how many breaths we take appeared to have a significant effect on overall health — this surprised me! There was also research into how the human skull has changed over time and the impact this has on breathing.

I highly recommend giving it a go, it is clear that this book is thoroughly researched and it’s an enjoyable read! If you want a brief summary, continue reading below!

The nose vs mouth breathing experiment

As part of research for the book, James Nestor designed an experiment where he and Anders Olsson, a breathing therapist, spent 20 days comparing breathing through the mouth and nose. Before the experiment, they were tested by doctors at Stanford University and then for 10 days they blocked their noses, forcing them to breathe through their mouths. For the 10 days they monitored key health indicators while sticking to a strict diet and routine. The Stanford tests were then repeated, before spending 10 days breathing through their noses with the same routine, tasks and monitoring. The tests were repeated a final time and results were collated.

Interestingly, despite such a short space of time, from mouth breathing Nestor and Olsson developed sleeping problems incuding sleep apnea and snoring, their stress hormones spiked and blood pressure increased. They also experienced fatigue, irritation and anxiety and Nestor developed a bacterial infection in his nose.

The nose breathing caused an immediate drop in blood pressure, their heart rates normalised, sleep problems disappeared within a few days and Nestor’s infection cleared up. In addition to this, both of them saw an increase in performance during aerobic exercise of 5 and 10%.

With only 2 subjects, this study isn’t the most robust, especially since they both had strong expectations and preference for nose breathing going into the experiment, but the results provide quantitative data and the trends are in agreement the with other research presented in the book.

Changes to facial structure

Nestor went to great lengths (and to great depths) to research the changes to the human skull over time. Comparing a modern human skull to one from hundreds of thousands of years ago, they will look very different with straight teeth, wide jaws and noses and larger faces.

The more we cooked, the more soft and calorific foods we ate, the larger our brains grew and the smaller our mouths and nasal cavities became. With the introduction of farming, humans gradually developed crooked teeth and breathing problems. Then around 300 years ago this spread worldwide with the industrialisation of farming with rapid changes resulting in smaller mouths, flatter faces and sinus problems.

These changes are not caused by breathing but cause problems to breathing. To correct this, devices to widen the mouth, breathing exercises and novel techniques have been successfully used leading to straighter teeth, changes to the structure of the face and improvements in breathing.

Breathing to good health

One technique mentioned in the book that I’d never heard of before was Tummo. Tummo is an ancient Tibetan practice meaning “inner fire” as it harnessed the power of breath to keep warm in the freezing conditions of the Himalayas. The Wim Hof method is a simplified version of Tummo, developed and popularised by Wim Hof himself.

In addition to these methods, the book explores different pranayama practices such as Nadi Shodhana (alternate nostril breathing) that can lower heart rate, blood pressure and sympathetic stress. Many breathing techniques can be used to soothe the nervous system and help improve sleep, stress and wellbeing. Interestingly, it also presents cases of individuals with an abundance of ailments who breathed themselves to good health and lived long and energetic lives.


I learned so much from reading this book, it introduced me to new breathing techniques and practices I’d like to explore further.

Personally I find that during yoga, I can easily tune into my breath. I enjoy pranayama and mindfulness practices and have no problems breathing through my nose. The rest of the time, I am not as aware of my breath and I breathe through my mouth at night.

I’ve tried taping my mouth at night a few times to force myself to breathe through my nose. It was so uncomfortable and made it impossible to sleep! I think I lasted no more than 30 mins before taking it off! After reading the book it makes me want to give it another try, maybe this time building up over time… let’s see!

This summary touches very lightly on the key points I picked up from the book. It contains many, many more valuable insights and research and I think I’ll need at least another read to absorb more.

Have you read Breath: A New Science of a Lost Art or are you considering reading it after this review? Get in touch or sign up to my newsletter below to hear more about my classes, thoughts and experiences.

Photo by Max van den Oetelaar on Unsplash

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