In Breath, science journalist James Nestor investigates something most of us never think about: how we breathe. He travels widely to explore the differences between mouth breathing and nasal breathing, and argues that how we inhale and exhale affects sleep, stress and overall health.
Mouth Breathing vs. Nasal Breathing#
Nestor argues that modern soft diets have changed human jaw structure, narrowing airways and making mouth breathing more common. In his account:
- Mouth breathing: Bypasses the nose's filtering and humidifying, and Nestor links it to snoring, sleep apnea and daytime tiredness.
- Nasal breathing: The nose and sinuses produce nitric oxide, which helps blood vessels widen, and slow nasal breathing tends to shift the nervous system toward "rest and digest".
Sleep Apnea and Snoring#
Breathing through the mouth during sleep can make the airway more likely to collapse. In obstructive sleep apnea, the airway repeatedly narrows or closes during sleep and the brain briefly wakes to restart breathing, fragmenting sleep so you get less deep sleep.
Sleep apnea is a medical condition. If you snore loudly, stop breathing or gasp in your sleep, or feel exhausted despite enough time in bed, see a doctor. It's treatable, and breathing exercises aren't a substitute for a diagnosis.
Nestor describes mouth taping (a small strip of tape to keep the lips closed during sleep) as a way to encourage nasal breathing. Evidence is limited. Don't tape if you can't breathe easily through your nose, and talk to a doctor first if you snore loudly or might have sleep apnea: taping can hide the symptom without treating it.
Breathing Practices#
Nestor outlines a few practices:
- 1.Slower breathing: In for about 5.5 seconds and out for about 5.5 seconds, roughly 5.5 breaths a minute. Nestor describes this as a natural "resonant" rhythm.
- 2.Breathing less: Nestor argues that practising lighter breathing builds tolerance to carbon dioxide, which he says improves oxygen delivery to cells (the Bohr effect). Evidence for health benefits is mostly early-stage.
Skip breath-holding exercises while driving or in water, and check with a doctor first if you're pregnant or have a heart or lung condition.
How This Connects to ARC#
ARC doesn't coach breathing. If you want to pair Nestor's slow breathing with something ARC does, try it during your 20-minute morning light walk; ARC's timer starts from your real sunrise and runs on your Lock Screen. For evening habits, see the evening wind-down ritual. ARC is a wellness app, not a medical device. If sleep problems persist, talk to a doctor. ARC isn't affiliated with or endorsed by James Nestor; this summary is our own.
ARC isn't affiliated with or endorsed by James Nestor or the publisher. This summary is our own reading of the book. Educational content, not medical advice.