Physiological sigh (cyclic sighing)

How do you do a physiological sigh?

You can do it sitting, standing or walking, with your eyes open. Nobody needs to notice.

In 2sIn 1sOut 6s

The exact timing isn’t sacred. What matters is the double breath in and an out-breath that’s longer than both. Breathform’s 2-1-6 count is one comfortable way to do it; that exact timing hasn’t been tested on its own.

Why the long breath out? Your heart speeds up slightly as you breathe in and slows as you breathe out. An out-breath that’s twice as long as the way in gives the slowing side more time, and most people feel their shoulders follow.

Why does your body sigh on its own?

Because your lungs need it. Without noticing, you sigh every few minutes, and those spontaneous sighs help keep the tiny air sacs in your lungs from collapsing (Severs et al. 2022).

Sighs seem to reset your breathing, too. In one study of 42 people sitting quietly, breathing grew more random in the breaths leading up to a sigh, and more orderly after it (Vlemincx et al. 2010). So the physiological sigh isn’t a trick someone invented. It’s a reflex you can borrow on purpose. If you’ve noticed you sigh a lot lately, why do I sigh so much? looks at that.

You’ll also read that the double breath pops open collapsed air sacs and is the fastest way to calm down. The air-sac part fits what natural sighs do. The fastest-way part is a claim nobody has tested.

What is the physiological sigh good for?

Small, sharp moments, when you have a minute or less: the red light, the gap between meetings, the moment before you reply to that message, the minute after a near miss on the bike. One or two sighs take 10 to 20 seconds; a minute is six or seven.

In one pilot with 47 students, one minute of cyclic sighing in real-life tense moments was linked to a bigger drop in anxiety five minutes later than doing nothing in particular (Riedl et al. 2026). For a short routine when you’re already wound up, see how to calm down. When anxiety sticks around, breathing exercises for anxiety has a fuller set.

Does cyclic sighing work better than meditation?

In one month-long trial, it did better on mood. 108 adults practised for 5 minutes a day for 28 days: cyclic sighing, box breathing, fast breathing with holds or mindfulness meditation. Every group felt less anxious after each session. Cyclic sighing lifted positive mood more than meditation did, and slowed resting breathing more too (Balban et al. 2023).

The groups were small, from 21 to 33 people. The practice was done at home and reported by the participants, and heart rate variability didn’t change in any group (Balban et al. 2023). The real-life pilot above points the same way, but it was small and short (Riedl et al. 2026).

So: promising, not settled. A good thing to try, with honest early evidence.

How well each breath is studied

• Physiological sighSome evidence
• Box breathingSome evidence

Every study on this page (4)

• Severs et al., 2022: Spontaneous sighs occur every few minutes and help prevent the collapse of alveoli, the lungs’ tiny air sacs (review).
• Vlemincx et al., 2010: In 42 healthy people sitting quietly, breathing became more random in the breaths before a spontaneous sigh and more orderly after it, suggesting a sigh resets breathing.
• Riedl et al., 2026: In a small pilot, one minute of box breathing or cyclic sighing in tense moments eased students' anxiety more than no exercise.
• Balban et al., 2023: Five minutes a day of cyclic sighing lifted mood a little more than mindfulness meditation, in 108 adults.

How many physiological sighs should you do?

One to three, when you want a quick reset. For a daily practice, the trial used 5 minutes, about 33 rounds at Breathform’s pace. Anything in between is fine: the player above runs for 90 seconds, and the plus button adds rounds. To repeat the trial’s month, set Reset to 33 rounds in Breathform and History keeps your days in a row.

More isn’t better if it makes you dizzy. If your fingers tingle or your head feels light, you’re taking in more air than you need: make the top-up smaller and the out-breath longer.

Why does the physiological sigh feel awkward?

Physiological sigh or box breathing: which is better?

They suit different moments. In a head-to-head pilot, one minute of either was linked to a bigger drop in anxiety than doing nothing, and box breathing was linked to fewer slips on an attention test (Riedl et al. 2026). In the month-long trial, cyclic sighing lifted mood more than meditation, while box breathing didn’t differ from it (Balban et al. 2023).

There’s a full guide to box breathing, with its own timer.

Questions people ask

Is the physiological sigh real?

Yes. Sighing is a reflex: you do it every few minutes without noticing, and it helps keep your lungs’ tiny air sacs open. The name “physiological sigh” for doing it on purpose was made popular by Andrew Huberman, a neuroscientist and one of the authors of the 2023 trial. The research on the deliberate version is still young.

Does the physiological sigh help you fall asleep?

We found no studies of it for sleep. It can help you settle when you’re wound up at bedtime, but the top-up breath feels a little stimulating to some people. Once you’re lying down, a slow breath without the double inhale, like 4-6 breathing, is the gentler way to drift off.

Does the physiological sigh lower cortisol?

There’s no evidence either way yet. The 2023 trial didn’t measure stress hormones, so claims that it lowers cortisol go beyond what was shown. What it did find, after a month of 5 minutes a day, was a better mood and a slower resting breathing rate than mindfulness meditation.

Should you breathe out through your nose or mouth?

Through your mouth, in the version that was tested: it makes the long out-breath easy and unhurried. Through your nose works too, especially somewhere quiet or at night. The part that matters is the shape: two breaths in through the nose, then a breath out that’s longer than both.

Can kids do the physiological sigh?

Yes, as a game: “sniff, sniff and a long sigh out.” Keep the breaths small, with no pushing, and stop after two or three. Children often like doing it together after a big feeling. Breathing exercises for kids has more breaths in the same spirit, with shapes to trace.