Can you give an exact protocol for the physiological sigh?

Take two consecutive inhales, then exhale slowly and fully through your mouth. You can do one sigh for a quick reset, or repeat the cycle continuously for five minutes as a practice. 1 2

1. First inhale: Inhale as deeply as you can through your nose. 3
2. Second inhale: Immediately take a brief, sharp second inhale through your nose to fill the lungs further. 4
3. Exhale: Slowly and fully exhale through your mouth until your lungs are empty. 5
4. Repeat as needed: One sigh may be enough; for a longer practice, repeat the cycle for five minutes. 6 7
5. If nasal breathing is difficult: You can do the breathing through your mouth instead. 8