The Physiological Sigh: Two Breaths In, One Long Breath Out

You already know how to do this one. You've done it countless times without thinking: after a long cry, at the end of a stressful day, when you finally sit down. A sigh — a deep breath in, a little extra top-up, and a long breath out — is one of the body's own ways of letting go.

The "physiological sigh" is simply that, done on purpose.

How to do it

Each sigh has three parts:

1. Breathe in through your nose — a comfortable, full-ish breath.
2. Take a second, smaller sip of air through your nose on top of it, as if topping up.
3. Breathe out slowly through your mouth — a long, unhurried, relaxed exhale, longer than the two in-breaths together.

Then pause naturally and do it again. A gentle rhythm is something like two seconds for the first in-breath, one second for the sip, and around six seconds for the out-breath.

That's it. When you repeat it for a few minutes, it's often called cyclic sighing.

Keeping it gentle

Because the in-breath has two parts, it's easy to overdo it — to take a giant gulp, then another, then blast the air out. That tends to feel more agitating than calming, and big, forceful breathing can leave people light-headed.

A few cues help:

• Keep the first breath ordinary, not maximal. The sip is small.
• Let the out-breath fall, rather than pushing it.
• On the long breath out, let your shoulders drop. This is the part most people notice.
• If you feel dizzy or tingly, stop and breathe normally. Next time, make everything smaller.

Why a sigh feels like letting go

Sighing is something people do spontaneously, often several times an hour without noticing, and especially at moments of relief or release. The long, slow exhale has a "settling" feel that many people recognise — the same feeling as putting down a heavy bag.

Doing it deliberately gives you a way to borrow that feeling. It's also easy to remember, quick to do, and doesn't need counting or holding.

What a 2023 study found

The physiological sigh got a lot of attention after a study published in 2023 in Cell Reports Medicine by researchers at Stanford. Around a hundred volunteers spent five minutes a day for a month on one of three breathing practices — cyclic sighing, box breathing, or a fast breathing pattern with holds — or on mindfulness meditation.

All four groups reported improvements in mood over the month. The cyclic sighing group reported the largest increase in positive mood, and the meditation group the smallest. It's an interesting result, but it's worth keeping in proportion: it was one study, with a modest number of people, using self-reported moods, and everyone improved to some degree. It doesn't mean sighing is a cure for anything, or that it will feel the same for everyone. You can read the full study here.

When to use it

Because it's short and simple, the physiological sigh suits in-between moments:

• After reading a difficult message, before replying.
• At your desk when you notice you've been holding your breath. (See screen apnea.)
• Before you walk into a room you're nervous about — as a pleasant reset, not as a ritual you must do first. See when calming tricks backfire.
• For a few minutes as your main breathing practice, if you like it.

Who should take it easy

The physiological sigh has no breath holds, which makes it gentler for many people than box or 4-7-8 breathing. Still, if you have a lung or heart condition, are pregnant, or simply feel unwell when you change your breathing, take it slowly and stop if anything feels wrong. Never practise breathing exercises while driving or swimming. See our guide to breathing exercises safely.

The short version

In through the nose, a little sip more, and a long, slow breath out through the mouth. Keep it soft and keep it small. It's the most natural breathing exercise there is — your body invented it before anyone gave it a name. For other patterns to try, see our beginner's guide to slow breathing.