Can you give an exact protocol for the physiological sigh?

Here's an exact protocol for performing the physiological sigh, as described by Andrew Huberman:

Physiological Sigh Protocol

1. First Inhale: Take a deep, full breath in through your nose, trying to fill your lungs completely.
2. Second Inhale: Before you exhale, take a brief, sharp inhale through your nose again—this is a "sneak" inhalation that should max out the inflation of your lungs.
3. Exhale: Following the two inhalations, exhale slowly and fully through your mouth. Aim to empty your lungs completely.
4. Repeat: You can repeat this sighing process for additional relief if needed. Typically, one effective physiological sigh can be sufficient to reduce stress, but you can do it multiple times if you prefer, especially in a five-minute protocol where you continue this cycle 1.

Additional Notes:

• The technique can be performed anywhere and at any time, making it a practical tool for stress management.
• If you experience difficulties breathing through your nose due to conditions like a deviated septum, you can adapt the method by using the mouth for one of the inhalations 2.

Cyclic Protocol

For a longer practice, a structured five-minute protocol involves continuously repeating the physiological sigh, consisting of two inhales followed by a long exhale throughout the duration 3.

This breathing technique is a quick and effective way to activate the parasympathetic nervous system, promoting calmness and reducing feelings of stress.