The physiological sigh: what the 2023 breathwork study actually found

2 peer-reviewed sources, DOI-verifiedUpdated Oct 1, 2026How we verify

The “physiological sigh” has become one of the most shared breathing tips online. It’s simple: two inhales through the nose, then one long exhale through the mouth. But what does the research actually show? Here is what the best-known study found, and what it didn’t test.

What is cyclic sighing?

A single sigh is something your body does on its own. Cyclic sighing means repeating that pattern on purpose for a few minutes:

1. Inhale through your nose until your lungs feel mostly full.
2. Take a second, shorter inhale to top up.
3. Exhale slowly and fully through your mouth, taking longer than both inhales together.

The long exhale is the key ingredient. You can try it with a visual pacer in our Breathing Regulator.

The 2023 study

Researchers at Stanford ran a remote randomized controlled study comparing three daily 5-minute breathing exercises with 5 minutes of mindfulness meditation, practised every day for a month. The breathing conditions were cyclic sighing, box breathing (equal inhale, hold, exhale) and cyclic hyperventilation with retention.

The main outcomes were mood, anxiety and markers of physiological arousal such as breathing rate. Breathwork, and especially exhale-focused cyclic sighing, produced greater improvement in mood and a larger drop in respiratory rate than mindfulness meditation.

What the study doesn’t tell us

• It compared breathing with meditation, not with doing nothing. Both groups did something calming every day.
• It lasted one month. We don’t know how the effects hold up over longer periods.
• It was a single study. That’s why cyclic sighing gets a B · Moderate grade in our Evidence Matrix, not an A.
• It wasn’t a study of anxiety disorders. It shows effects on everyday mood and arousal, not a replacement for professional care.

Why a long exhale may help

Slow breathing with a longer exhale is linked with higher heart rate variability, a marker of how flexibly the nervous system shifts between activation and rest. A systematic review of slow-breathing studies in healthy people connected breathing under ten breaths a minute with these autonomic changes and with psychological effects.

How to use it

• In a stressful moment: one to three cycles can help you feel more settled.
• As a daily practice: five minutes a day, the dose used in the study.
• Stop if you feel dizzy. Breathe normally until it passes.

If anxiety is frequent or gets in the way of daily life, breathing exercises are a useful skill, but talk to a doctor or licensed therapist as well.