The double inhale: a sigh on purpose

You already do this. Several times an hour, without noticing, you take a slightly bigger breath, sometimes with a second small sip of air on top, and then let it out slowly. We call it a sigh. Many people sigh when something ends: a task done, a wait over, a worry set down.

Taking a sigh on purpose is a small, old idea with a recent name. It is called the physiological sigh, or cyclic sighing. This piece covers what a sigh is for, what one study found, and what that study cannot tell us.

What a sigh is for

One long-standing view is that quiet breathing lets some of the lungs’ tiny air sacs slowly go flat, and that an occasional bigger breath opens them again. Sighs also seem to reset the rhythm of breathing for a moment. In 2016, researchers described a small group of cells in the brainstems of mice that appears to produce sighs. So a sigh is not only a feeling you express. It is also something the body builds in and does at its own pace.

The long out-breath that follows is the part we would keep if we could keep only one. We have written elsewhere about why the out-breath is the side of the cycle that leans toward settling.

The double inhale

The deliberate version has three parts.

1. Breathe in through the nose, comfortably full.
2. Without breathing out, take a second, shorter sip of air through the nose to top the lungs up.
3. Let a long, slow breath go out through the mouth, as if fogging a cold window, until it has finished by itself.

That is one round. Three to five rounds are plenty. Then breathe however you like. Do not strain at the top. The second inhale should feel like topping up a glass, not like lifting something heavy. If the second sip feels fiddly, leave it out. One inhale and a longer exhale is a perfectly good version.

What one study found

In 2023, researchers randomly assigned about a hundred adults to one of four daily practices of five minutes, for a month: three kinds of breathing, or mindfulness meditation. Compared with mindfulness meditation, the three breathing practices together were followed by a bigger gain in positive mood and a lower resting breathing rate. On its own, only cyclic sighing, the double inhale with a long exhale, stood out clearly.

Now the limits. Mood was reported by the participants themselves, and they knew which practice they were doing. The differences were modest and the groups were small, with 21 to 33 people each. The study ran remotely, in 2020. The study cannot tell us which part of the sigh does the work, the second inhale or the long exhale. And it says nothing about any condition. It is a promising finding, not a promise.

Take care

If you feel light-headed, stop and breathe normally. Keep every breath comfortable, never strained. If you have asthma, a heart or lung condition, or you are pregnant, ask your clinician before trying new breathing patterns.

The next time you catch yourself sighing, do not apologize for it. Notice what came just before, and what you might put down.