The physiological sigh: two breaths in, one long breath out
You already sigh without meaning to, every few minutes. Sighs are a built-in reflex controlled by a small group of cells in the brainstem [1], and they seem to act as a kind of reset for your breathing pattern [2].
The physiological sigh simply does this on purpose, with extra emphasis on breathing out.
How to do it
You can do this sitting, standing or lying down, eyes open or closed.
- Breathe in through your nose. Take a full, comfortable breath in through your nose.
- Top it up. Without breathing out, take a second, shorter sip of air through your nose to fill your lungs a little more.
- Breathe out slowly through your mouth. Let the air out through your mouth, slowly and completely. Make the out-breath noticeably longer than the two in-breaths together.
- Repeat. One to three sighs can be enough in the moment. For a fuller practice, repeat for up to five minutes at a relaxed pace.
What the research says
The best evidence comes from a 2023 randomised study at Stanford. 108 adults practised cyclic sighing, box breathing, a fast breathing technique or mindfulness meditation for five minutes a day for a month. All groups felt less anxious and less negative, with no real difference between them on anxiety. But cyclic sighing produced the biggest improvement in positive mood and the largest drop in resting breathing rate, and it was the only technique that clearly beat mindfulness on both [3].
It's one study, with small groups and mostly students, so the result needs repeating. But it fits a wider pattern: breathing techniques that lengthen the out-breath tend to be the calming ones.
When it's worth using
- In the moment: when stress spikes and you want something that takes seconds.
- After a shock or a rush: a near miss, bad news, running for a train.
- As a short daily practice: five minutes, as in the study.
Safety
If you feel lightheaded, slow down and take smaller breaths in. The out-breath should be relaxed, not forced.
In MoodFire
MoodFire doesn't have a guided sigh, but its Breathe tool is built on the same principle of slow, unhurried breathing out. If you'd like a guided rhythm to follow, try a one-minute Breathe session after a few sighs.
Common questions
What's the difference between a physiological sigh and cyclic sighing?
A physiological sigh is a single double-inhale, long-exhale breath. Cyclic sighing is doing it repeatedly, usually for about five minutes.
How quickly does it work?
Many people notice a difference after one to three sighs. In the Stanford study, the benefits on mood built up over a month of daily five-minute practice.
Should I breathe out through my nose or mouth?
The usual instruction is in through the nose, out through the mouth, because it's easier to make the out-breath long and slow that way.
Sources
- Li P, Janczewski WA, Yackle K, et al. The peptidergic control circuit for sighing. Nature. 2016;530(7590):293–297. doi:10.1038/nature16964
- Vlemincx E, Van Diest I, Lehrer PM, Aubert AE, Van den Bergh O. Respiratory variability preceding and following sighs: a resetter hypothesis. Biological Psychology. 2010;84(1):82–87. doi:10.1016/j.biopsycho.2009.09.002
- Balban MY, Neri E, Kogon MM, et al. Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. 2023;4(1):100895. doi:10.1016/j.xcrm.2022.100895