James Nestor, on pp. 41-42 of his book Breath: the New Science of a Lost Art, claims the following.

The right nostril is a gas pedal. When you're inhaling primarily through this channel, circulation speeds up, your body gets hotter, and cortisol levels, blood pressue, and heart rate all increase. This happens because breathing through the right side of the nose activates the sympathetic nervous system, the "fight or flight" mechanism that puts the body in a more elevated state of alertness and readiness. Breathing through the right nostril will also feed more blood to the opposite hemisphere of the brain, specificially to the prefrontal cortex, which has been associated with logical decisions, language, and computing.

Inhaling through the left nostril has the opposite effect: it works as a kind of brake system to the right nostril's accelerator. The left nostril is more deeply connected to the parasympathetic nervous system, the rest-and-relax side that lowers temperature and blood pressue, cools the body, and reduces anxiety.

... Our bodies operate most efficiently in a state of balance, pivoting between action and relaxation, daydreaming and reasoned thought. This balance is influenced by the nasal cycle, and may even be controlled by it. It's a balance that can also be gamed.

A question on this site describes we only breathe out of one nostril at a time: at any given time, one of our nasal cavities will be more open than the other, and this switches back and forth every couple hours. For the most part, we are unaware of this. (At any rate, I was!)

I am very curious about Nestor's claim that the balance can be gamed. It seems that one could prepare effectively for a math exam by practicing right-nostril breathing, or for sleep by practicing left-nostril breathing. Is this the case?

  • $\begingroup$ “Breathe on me breath of God”. Notice the difference in spelling which reflects the difference in pronunciation. $\endgroup$
    – David
    Jul 12, 2020 at 19:16
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    $\begingroup$ I ve never heard any citations stating a basis of research on which side nostril causes what mental states, so the research is probably lacking. Wim hoff stuff conversely does have evidence. $\endgroup$ Jul 15, 2020 at 7:11
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    $\begingroup$ A quick search shows that there is evidence that nostril breathing influences the autonomic nervous system, but currently not much evidence that right vs left nostril breathing influence different states. $\endgroup$
    – Kai Dijon
    Sep 12, 2020 at 17:42
  • $\begingroup$ Any kind of higher awareness of breathing is likely to improve mental abilities, for one it gives free divers the ability to dive a lot longer, and Wim Hof uses it to stay consciou s and submerged in ice water for 112 minutes, which wasn't believed to be humanly possible previously. It must be difficult to tell the difference of a breathing exercise versus an alternate nostrile breathing exercise. $\endgroup$ Sep 29, 2020 at 6:53

1 Answer 1


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681046/ Assessment of the Effects of Pranayama/Alternate Nostril Breathing on the Parasympathetic Nervous System in Young Adults
Result and Conclusion: This study showed that the parasympathetic tone was enhanced appreciably in the participants. The observations of this study suggest that the yogic exercise of A.N.B. influences the parasympathetic nervous system significantly.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978938/ Slow Yogic Breathing Through Right and Left Nostril Influences Sympathovagal Balance, Heart Rate Variability, and Cardiovascular Risks in Young Adults
Short-term practice of LNB improves vagal tone, increases HRV, and promotes cardiovascular health of medical students. Practice of RNB increases sympathetic tone and could jeopardize cardiovascular health.

There seems to be some evidence that this works.

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    $\begingroup$ note the sample sizes, n=30 which makes the conclusions of the study very weak at best, the differences are equally miniscule (and swamped by the margins of error). this is just bad applications of statistics in the guise of a preliminary study. $\endgroup$
    – John
    Sep 29, 2020 at 10:33

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