The 4 breathing secrets that will transform your health today | James Nestor

February 26, 2026·59 min·5 clips

Two men sealed their noses for 10 days, causing blood pressure spikes and cognitive decline—just like many people breathe nightly.

ZOE Science and Nutrition is a health podcast produced by the nutrition science company ZOE, hosted by Jonathan Wolf. James Nestor is the author of Breath, an internationally bestselling investigation into the physiology and history of human breathing. The episode opens with a description of the 10-day nasal-occlusion experiment, in which Nestor and a colleague had their nostrils sealed with silicone and breathed exclusively through their mouths. Within days, blood pressure climbed, sleep became fragmented, stress hormones surged, and cognitive markers dropped — a physiological profile resembling accelerated ageing. The experiment was conducted under research supervision. Nestor notes this pattern mirrors how many people breathe every night without awareness. In the rapid-fire Q&A segment, Nestor confirms that most people breathe wrong (yes), that mouth breathing is unhealthy (no), and that the biggest error is breathing too much. He traces his interest to his own health problems: years of bronchitis and mild pneumonia that he could not resolve through diet or sleep hygiene. A doctor friend suggested a breathwork class, which he attended reluctantly, and his respiratory problems resolved. Since then he has not experienced a recurrence. He brought the story to his literary agent, who thought it was a terrible book idea; she eventually agreed to develop a proposal after several years of his persistence, and the book was published six weeks into the COVID-19 lockdown in 2020, at which point widespread anxiety about respiratory health made it an immediate success. The episode goes on to cover the anatomy of breathing — nasal versus oral, diaphragmatic versus thoracic — the role of CO2 in oxygen delivery (the Bohr effect), and specific techniques for retraining dysfunctional breathing patterns. Nestor is careful to note his experience is not a controlled study and results vary, but cites research on breathing mechanics throughout.

As heard by us

A clear case for treating breathing like a health habit rather than background noise.

Breathing starts as a basic reflex here, then quickly turns into something that touches sleep, blood pressure, stress, and cognition. The setup is simple and hard to ignore: two healthy men had their noses sealed shut for 10 days and breathed only through their mouths while…

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Why you'd press play

If your sleep, stress, or daytime focus feels off, start with the nose.

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