The physiological sigh, explained
Two inhales through the nose followed by one long exhale — the fastest way to calm down, backed by a Stanford study. How it works and when to use it.
The physiological sigh is the body's own reset button. You do it without noticing when you settle after crying or before sleep: a full inhale, a second short sip of air on top, then a long exhale.
Done deliberately, one to three of these can take the edge off stress in under a minute — which is why it has become the go-to quick fix popularised by Stanford neuroscientist Andrew Huberman.
How to do it
- 1Breathe in fully through your nose.
- 2At the top, take a second short sip of air through your nose to top up the lungs.
- 3Breathe out slowly and completely through your mouth.
- 4Repeat one to three times, or up to five minutes for a deeper reset.
The science
Deep in your lungs are millions of tiny air sacs called alveoli. Under stress some of them collapse, and the second inhale pops them back open so they can offload carbon dioxide efficiently.
The long exhale then dumps that carbon dioxide and activates the calming vagus nerve. A 2023 Stanford trial found five minutes a day of this 'cyclic sighing' improved mood and lowered breathing rate more than mindfulness meditation did.
Common mistakes
Skipping the second sip. The double inhale is what makes it work — do not merge it into one breath.
Rushing the exhale. Let it be slow and complete.
When and how often
Use one or two sighs the moment stress spikes — before a hard conversation, in traffic, between tasks. For an ongoing effect, do five minutes daily.
Common questions
How fast does the physiological sigh work?
Often within one to three breaths. It is the quickest real-time tool here for calming a stress spike.
Can I do too many?
It is very safe — this is how your body sighs on its own. If you feel light-headed, simply return to normal breathing.
Sources: Balban et al., Cell Reports Medicine (2023) — Cyclic sighing
Practise Physiological sigh with a guided timer.
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