Physiological Sigh
The physiological sigh is the fastest evidence-based stress reduction technique we know of. Double inhale through the nose, then a long exhale through the mouth. Repeat for thirty seconds.
Why it works
Section titled “Why it works”The double inhale fully inflates collapsed alveoli in the lungs, allowing more efficient CO₂ offload on the long exhale. CO₂ offload is the actual signal that drops sympathetic tone — not “calm thoughts,” not “deep breathing.” It is the chemistry that does the work.
Stanford’s Andrew Huberman lab popularized this protocol after Krasnow Lab research showed measurable HRV improvement within a single sigh.
When to run it
Section titled “When to run it”- Stress spike that came out of nowhere
- The moment before a hard task you have been avoiding
- After a meeting that ran long and went sideways
- Any time you notice a held breath
Variant
Section titled “Variant”| Duration | Sighs | Command |
|---|---|---|
| 30s | 4-5 | flowe reset 30 --protocol physiological_sigh |
This is the shortest protocol flowe ships. Use it when you have less than a minute and need to actually shift state.