Editors Reads Verdict
Nestor's thorough investigation of breathing science is one of the more surprising and practically useful health books in years. The idea that most people breathe sub-optimally, with measurable health consequences, is well-documented and actionable.
What We Loved
- The nasal breathing vs. mouth breathing research is genuinely compelling and well-sourced
- Nestor's personal self-experimentation adds credibility and readable drama
- The historical and anthropological context is fascinating
- Practical techniques (Buteyko, coherent breathing, box breathing) are clearly explained
Minor Drawbacks
- Some claims extend further than the evidence strictly supports
- The folk and traditional material requires more critical treatment
- Some readers want more clinical evidence and less personal narrative
Key Takeaways
- → Mouth breathing causes measurable structural changes in the face and teeth — and health problems
- → Nasal breathing filters, humidifies, and nitric-oxide-enriches air in ways mouth breathing does not
- → Slow, diaphragmatic breathing at approximately 5-6 breaths per minute has significant cardiovascular benefits
- → Most people breathe too fast and with too little carbon dioxide tolerance
- → Ancient practices (pranayama, Wim Hof, Buteyko) have real physiological effects
| Author | James Nestor |
|---|---|
| Publisher | Riverhead Books |
| Pages | 304 |
| Published | May 26, 2020 |
| Language | English |
| Genre | Health, Science, Self-Help |
| Difficulty | Beginner |
| Best For | Anyone interested in improving their health through breathing practices, particularly those with sleep apnea, anxiety, asthma, or general wellness goals. |
The Overlooked Health Practice
James Nestor is a science journalist who became fascinated by breathing after attending a freediving class. The observation that changed his focus: trained freedivers could hold their breath for extraordinary periods, not primarily because of lung capacity, but because of how they breathed between dives. He began investigating the science of breathing and found a field with centuries of accumulated wisdom and decades of neglected scientific research.
Breath is the synthesis of that investigation: a well-reported, occasionally surprising examination of how breathing affects health and how most people in the modern world are doing it suboptimally.
The Nose vs. The Mouth
The book’s central finding is deceptively simple: nasal breathing is significantly healthier than mouth breathing, and a large proportion of the population habitually breathes through their mouths. Nestor documents the consequences: the nasal passages filter air, humidify it, and — crucially — produce nitric oxide (a vasodilator that improves oxygen delivery to tissues). None of these benefits are available to mouth breathers.
To demonstrate the point, Nestor and his collaborator Dr. Jay Jayakar plugged their noses and breathed exclusively through their mouths for ten days, tracking their health metrics. The results — documented with rigorous measurement — were alarming: blood pressure increased, sleep quality deteriorated, snoring appeared.
The Perfect Breath
Drawing on research from the Cleveland Clinic, the Framingham Heart Study, and independent researchers, Nestor identifies an optimal breathing pattern: approximately 5.5 seconds in, 5.5 seconds out — about 5.5 breaths per minute. This pattern, which appears in diverse traditions from pranayama to Catholic rosary prayer to mantra meditation, consistently produces measurable improvements in heart rate variability, blood pressure, and subjective wellbeing.
Carbon Dioxide and the Bohr Effect
One of the book’s most counterintuitive insights concerns CO2. We typically think of CO2 as a waste product to be exhaled as rapidly as possible. But CO2 triggers the Bohr effect — the mechanism that releases oxygen from haemoglobin into tissues. Chronically over-breathing (exhaling too much CO2) reduces oxygen delivery to the brain and muscles.
Final Verdict
Breath is an accessible, well-reported, and practically valuable examination of a health practice we take entirely for granted. The recommendations are simple, free, and well-supported by evidence.
Our rating: 4.5/5 — An eye-opening investigation into the most basic human action. The nasal breathing prescription alone is worth the cover price.
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