The physiological sigh

A double inhale through the nose then a long exhale to reset an overwhelmed state.

Why it works

A physiological sigh — two inhales (the second a short top-up) followed by a long exhale — reinflates collapsed alveoli in the lungs and offloads accumulated carbon dioxide efficiently. This is the body’s own built-in reset, occurring naturally during sleep and after crying; doing it deliberately can quickly lower arousal and clear a foggy, overwhelmed state so you can re-engage with energy.

How to do it

1. Inhale fully through the nose, then add a second short sniff to top off the lungs.
2. Exhale slowly and completely through the mouth.
3. Repeat one to three times whenever you feel flooded or stuck before re-engaging.

Evidence

The physiological sigh is a documented natural mechanism for reinflating the lungs and regulating CO2, and recent work suggests deliberate cyclic sighing improves mood and arousal. (rct)

It’s a fast acute reset, not a treatment for sustained stress. Effects are real but short-lived and modest in size.

Sources

• Balban et al. (2023), controlled breathwork including cyclic sighing and mood/physiology, Cell Reports Medicine

Common mistake

Doing many rapid sighs in a row as if more is better, which can over-ventilate and cause light-headedness. One to three deliberate sighs is the dose.