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. A dedicated brainstem circuit was identified as the neural generator of the sigh, confirming it is a hardwired reflex rather than an incidental deep breath. (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
• Balban MY, Neri E, Kogon MM, Weed L, Nouriani B, Jo B, Holl G, Zeitzer JM, Spiegel D, Huberman AD (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine, 4(1):100895.
• Li P, Janczewski WA, Yackle K, Kam K, Pagliardini S, Krasnow MA, Feldman JL (2016). The peptidergic control circuit for sighing. Nature, 530(7590):293-297.

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.