Physiological Sigh: How to Do It (Free Guided Timer)

The physiological sigh is a double inhale followed by a long exhale. Your body already sighs on its own every few minutes. Doing it on purpose gives you a short pause when stress spikes, and it takes only a few seconds.

What is a physiological sigh?

You breathe in twice through your nose, then out once through your mouth. The second inhale tops up your lungs, and it can be shorter and smaller than the first. Then you let all the air out slowly.

Spontaneous sighs happen every few minutes to reinflate the tiny air sacs in the lungs, and people sigh more when they're stressed or short of oxygen (Li et al., Nature, 2016). The deliberate version borrows that reflex.

When researchers repeat physiological sighs back to back for a few minutes, they call it cyclic sighing. That is what the Stanford trial tested, rather than single sighs.

Where the sigh comes from in the brain

In 2016, a team that included Jack Feldman's lab at UCLA and Mark Krasnow's lab at Stanford traced sighing to a small circuit in the mouse brainstem (Li et al., 2016). Two small groups of nerve cells send peptide signals to the preBötzinger complex, the area that sets the breathing rhythm, where roughly 200 neurons carry the matching receptors. Putting either peptide into that area set off sighs. Blocking both receptors stopped sighing, and removing the neurons that carry them wiped out sighs while ordinary breathing carried on.

A later Stanford team, which included the neuroscientist Andrew Huberman, asked the practical question: if the body sighs on its own, does sighing on purpose help with stress?

What the research shows

In a 2023 randomized trial from Stanford (Balban et al., Cell Reports Medicine, 2023), 108 adults spent 5 minutes a day for a month on one of three breathing practices (cyclic sighing, box breathing or cyclic hyperventilation) or on mindfulness meditation. Positive mood rose more in the breathing groups than in the meditation group. Cyclic sighing was the one practice that stood out from meditation on its own, for both mood and resting breathing rate. Anxiety went down in every group, meditation included, with no difference between them.

Nobody knows exactly why it works. The trial's authors point to the exhale: cyclic sighing, the practice that puts the most weight on a long breath out, had the clearest effect. One theory is that the regulated breathing used in practices like meditation and yoga stimulates the vagus nerve, part of the body's calming parasympathetic system (Gerritsen & Band, 2018). Treat that as a model rather than settled fact.

How to do the physiological sigh

These steps follow the instructions the Stanford trial gave its participants (Balban et al., 2023).

1. Breathe in slowly through your nose.

2. Once your lungs feel full, breathe in once more through your nose to fill them completely. This second breath can be shorter and smaller than the first.

3. Breathe out slowly through your mouth until your lungs are empty.

4. Repeat. One or two rounds make a quick pause. In the trial, people repeated the pattern for 5 minutes a day. If breathing out through your mouth feels awkward, the trial allowed doing it all through the nose.

When to use it

A single round is short enough to do almost anywhere without anyone noticing: when stress spikes, at your desk between emails, or two or three times before you walk into a hard conversation.

If you have panic attacks, talk to a doctor or therapist. Breathing exercises can support you, but they aren't a treatment. If anxiety turns up most days, what to expect from therapy for anxiety explains how that work usually goes.

How it compares with other breathing techniques

The sigh is the shortest of the three, so it suits a quick pause. You can follow a sigh or two with a few minutes of slower breathing if you want a longer break.

Can you overdo it?

The sigh has no breath hold and no fast breathing. If you feel light-headed, stop and breathe normally.

If you find yourself reaching for it dozens of times a day, notice that. Ongoing stress usually needs more than a breathing exercise, and a doctor or therapist can help you work out what's behind it. Therapy vs self-help covers how to tell when it's time to get support.

Pairing a sigh with a few lines of writing

If you journal, you could try following a sigh with a few minutes of writing:

1. Notice that you're stressed or scattered.

2. Do one to three physiological sighs.

3. Open your journal and write the first honest sentence that comes.

Nobody has tested this pairing as such, so treat it as an experiment. For the evidence on the writing side, the science of journaling covers what 146 studies found.

Frequently Asked Questions

What is the physiological sigh?

A double-inhale breathing pattern: two breaths in through the nose, the second one shorter to top up the lungs, then a long breath out through the mouth. Your body does it on its own every few minutes, and more often under stress.

How long does the physiological sigh take?

One round takes a few seconds, and one or two rounds make a quick pause. In the 2023 Stanford study, people repeated it for 5 minutes a day.

Is the physiological sigh backed by science?

There is some good evidence. In a 2023 randomized trial (Balban et al., Cell Reports Medicine), 108 adults did 5 minutes a day of a breathing practice or mindfulness meditation for a month. Cyclic sighing lifted mood and lowered resting breathing rate more than meditation did. Anxiety fell in every group, meditation included.

How is the physiological sigh different from box breathing?

Box breathing uses four equal counts, two of them holds. The physiological sigh has no hold and is built around one long exhale, so a round is short and easy to do discreetly. In the Stanford study, cyclic sighing showed the clearest effect on mood.

Who discovered the physiological sigh?

Sighing is a normal breathing reflex that happens every few minutes. In 2016, the labs of Jack Feldman (UCLA) and Mark Krasnow (Stanford) traced the brainstem circuit that produces sighs in mice (Li et al., Nature). In 2023, a Stanford team that included Andrew Huberman tested doing it on purpose (Balban et al., Cell Reports Medicine).

Sources

• Li P, Janczewski WA, Yackle K, et al. The peptidergic control circuit for sighing. Nature. 2016;530:293-297.
• 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.
• Gerritsen RJS, Band GPH. Breath of life: the respiratory vagal stimulation model of contemplative activity. Frontiers in Human Neuroscience. 2018;12:397.