Physiological sigh is two inhales through the nose followed by one long exhale through the mouth, a fast way to settle.
The second sniff tops up the lungs; the long mouth exhale dumps charge. In 📝Breathwork a few of these are used when the person is spiked and a slow cadence is too far away. It is a method, not a medical protocol, not a diagnosis, and not a guarantee. Two or three cycles is a dose; a long set is not.
Clients feel a drop after the out-breath. Dizziness, tingling, or panic means stop and return to 📝nasal breathing. Chest pain is a referral. This is not hyperventilation — the exhale is long and the set is short.