breathe.

Aside from the fact that we’re obligate aerobes, what makes breathing so special? Zen, Daoist, Sufist, Jainist, Tibetan, and Theravadan meditation techniques all incorporate “concentration on breath”, and modern mindfulness programs of the “dulcet British man tells you to let thoughts pass like clouds on a blue sky” variety implore the same. Nowhere in the definition of meditation (”nonjudgmental awareness”) is breath mentioned, so it’s curious that so many techniques have convergently evolved this focus.

Many lay resources (Wikipedia links to this website, which has a picture of a palm tree and uses Papyrus font) claim that that slow diaphragmatic breathing “maximizes the amount of oxygen that goes into the bloodstream.” I am skeptical. Healthy people have 97-99% oxygen saturation on room air, this number is limited by red blood cell binding, not ambient O2, and I intuitively doubt that wearing a nasal cannula has ever lead to transcendence. If anything, slow breathing increases CO2, which might benefit people with panic-induced hyperventilation, but was probably not the reason Gautama Buddha was big on controlled breathing.

Here’s a more plausible hypothesis:

During above tidal inhalation (as was seen in Hering Breuer’s reflex), stretch of lung tissue produces inhibitory signals in the vagus nerve, which ultimately shifts the autonomic nervous system into parasympatho-dominance, that results in a calm and alert state of mind. (Source)

If this is true, then deep breathing is essentially a body hack: pull on the vagus nerve down there, get some relaxation up here. A fringe argument could even be made that the “mindful detachment” part of meditation is a gimmick, and the real physiologic work is done by the breath itself.

Is this true?

Controlled breathing does seem to have a beneficial effect on pain, blood pressure, and mood during smoking cessation. (Interestingly, fast and slow deep breathing show similar results.) However, this doesn’t prove that relaxation is the work of Las Vagus—it’s just as possible that the act of focusing on breath is what causes relaxation, not the lung stretch. Accordingly, some studies have looked at direct vagal stimulation, which has no effect or great promise depending on whom you ask. Let us also note that forms of mindfulness meditation that place less emphasis on breath have similar results to those that do.

I am not an expert in this field; I would be happy to hear from someone who is. My hunch is that deep breathing and meditation are two separate things which work, very, very well together. They work together because a) deep breathing has a chemical calming effect that makes it easier to control one’s thoughts, and b) because meditation is about focus, and it’s easier to focus on breath than anything else. If you meditate to ambient noise, there are a hundred fragments of noise from which to pick. If you meditate on sunrise or sunset, there are a thousand colors from which to choose. But if you close your eyes and focus on breath, then there is only one choice to make. Voluntary breath is the smallest unit of control that we can exert. Breath occurs on a single axis. In. Out. Breathe.