Physiological sigh vs box breathing: what a head-to-head trial found, and which to pick

Two breathing exercises dominate the internet: the physiological sigh, and box breathing. Both take minutes, both cost nothing, and people argue about them. The best-known trial put them in the same study. This page reads it closely, then turns it into a decision.

The two techniques in one minute

Physiological sigh (cyclic sighing). Breathe in through your nose, add a second short sip of air at the top, then breathe out slowly through your mouth for longer than you breathed in. No holds, no counting. The full physiological sigh guide has the steps.

Box breathing. Four equal phases: breathe in, hold, breathe out, hold. The Cleveland Clinic describes breathing out fully first, then in for four counts, holding four, out four, holding four, for three or four rounds, and advises staying at your comfort level without straining.

What the trial compared

The study was a remote randomized trial from Stanford, published in Cell Reports Medicine in 2023. It enrolled 108 adults. Participants practised for five minutes a day for 28 days. Groups: cyclic sighing (30 people), box breathing (21), cyclic hyperventilation with breath retention (33), and a mindfulness meditation comparison group (24).

One detail most pages skip: the box breathing in the trial was personalized. People first took a maximal inhale and a timed slow exhale, and that exhale length set the count for all four phases, from about 3 to 4 seconds up to 8 to 10 seconds.

The numbers, side by side

Average change per person per day, before to after a session. Positive affect and negative affect use the PANAS scale; state anxiety uses the STAI.

Measure	Cyclic sighing	Box breathing	Mindfulness meditation
Positive affect	+1.89 (p = 0.025)	+1.84 (p = 0.026)	+1.22 (p = 0.06)
Negative affect	-1.48	-0.83	-1.62
State anxiety	-3.85	-3.75	-3.95
Breathing rate vs meditation	Significantly lower	Not reported as significant	Baseline comparison

How to read it:

• On mood, the two breathing practices are nearly identical (1.89 vs 1.84). The difference is in the comparison group: only cyclic sighing was statistically better than mindfulness meditation for positive mood, according to the paper.
• On anxiety and negative mood, everyone improved, with no significant difference between groups. Meditation actually had the largest average drop in both. Breathing was not shown to be better for anxiety.
• On breathing rate, the sigh group slowed down significantly more than meditation did. Box breathing did not reach significance.
• Heart rate, HRV and sleep did not change significantly in any group.

How much weight the result can take

Not much more than "the sigh looks promising". The authors describe the study as exploratory. It was run remotely with little control over how people practised, followed people for four weeks, and the groups were small (21 people did box breathing). Participants were mostly psychology undergraduates, the physiology came from a wearable device, and one author later became an advisor to the maker of that device. The trial was not built to rank one breathing practice above another, so "sigh beats box" is a hint, not a verdict. The authors conclude that daily five-minute cyclic sighing has promise as a stress management exercise.

Which one to pick

Your situation	Try	Why
Two minutes before a meeting or call	Physiological sigh	No counting, easy to do quietly
You want a steady rhythm to settle into	Box breathing	Even counts give your attention something to follow
Holds make you uneasy	Physiological sigh	It has none
Counting makes you more tense	Physiological sigh	Nothing to count
You like structure or a pace	Box breathing	The counts are the point
Evening wind-down	Either, or 4-7-8	Neither was shown to change sleep; choose by feel

A fair starting plan: do the sigh for a week, then box breathing for a week, and note how you feel after each. You are the sample that matters. The free breathing timer paces both patterns.

A one-week test you can run yourself

Group averages hide individual differences, so use your own data. Days 1 to 3: five minutes of the sigh once a day, same time. Days 4 to 6: five minutes of box breathing at that time. After each session, write one word for how you feel and rate it from 1 to 5. On day 7, repeat whichever scored better. Two caveats: a week of self-ratings is not a study, and novelty alone can lift a score, so repeat the better one for another week before deciding. If neither helps, that is useful to know too.

Common mistakes with each

• Sigh: a loud second inhale. Make it a quiet top-up through the nose.
• Sigh: pushing the exhale. Let the air leave on its own.
• Box: counts too long. If four feels strained, shorten all four phases equally.
• Box: tensing the shoulders during holds. Let them drop.
• Both: expecting instant effects. The trial looked at a daily habit across weeks.

Safety before you start

Ask a doctor before any breath-holding practice if you have a heart or lung condition, tend to faint or are pregnant. Stop and breathe normally if you feel dizzy or tingly. Breathing practice is general wellbeing, not a treatment, and does not replace professional care. For other popular practices sorted by evidence, read the vagus nerve exercises guide.