quiettime · breath · updated 2026-10-28

What your breath says
while you sit

Your breathing is the one part of a sit you can measure without a lab. Three numbers carry most of the information: how fast you breathe, how long your exhale runs against your inhale, and whether the breath moves your belly or your chest. Here is what the research supports for each, and where it stops.

How fast you breathe

A resting adult breathes about 12 to 18 times a minute.¹ Slow-breathing research works well under that: a systematic review of 15 studies in healthy people defined slow as under 10 breaths a minute, and many of the protocols paced people at 6 or 5.5.² The largest review of what slowing down does to the heart pooled 223 studies and found the vagal part of heart rate variability rose during slow breathing, right after a single session, and after multi-week programs.³ In the Stanford five-minute trial, the breathing groups' day-to-day resting rate fell more over a month than the meditators' did.⁴ More on what counts as normal and what counts as slow.

How long you breathe out

This is the one where the evidence is honestly mixed. A 2014 study of 30 people found that a long exhale relative to the inhale raised self-reported relaxation and stress reduction more than the breathing rate itself did.⁵ A 2024 study of 828 people, the largest on the question, varied both rate and exhale ratio across one ten-minute session and found that a slower rate predicted lower anxiety afterward, while the exhale ratio predicted nothing.⁶ The exhale-heavy pattern in the Stanford trial, cyclic sighing, produced the biggest per-session lift in mood, but anxiety fell about equally in every group.⁴ The whole argument, with the numbers, is on the exhale page.

Belly or chest

One randomized-style trial of 40 healthy adults trained half of them in diaphragmatic breathing for 20 sessions over 8 weeks, with a feedback device, slowing them to about 4 breaths a minute. Afterward the trained group reported less negative affect, scored higher on a sustained-attention test, and had lower salivary cortisol than the untrained group.⁷ It is a small trial, and intensive coaching is not the same as thinking about your belly for a minute. The hand test and the caveats are on the belly page.

What breathwork does overall

A 2023 meta-analysis pooled 12 randomized trials, 785 adults, and found breathwork lowered self-reported stress by a small-to-medium amount (g = −0.35) compared with control conditions. Anxiety (20 trials) and depressive symptoms (18 trials) moved by similar amounts.⁸ Most of the trials were at moderate risk of bias, and the authors say so, urging caution. Small to medium and real is the fair summary.

Can a phone see any of this?

Yes, and not only ours. In a 2022 validation, 50 people sat still in front of a phone's front camera and the breathing rate it computed was within 0.78 breaths a minute of the reference, on average.⁹ That was a short still measurement, not a meditation. quiettime reads two of these three during the sit itself: your breaths per minute and how long each inhale and exhale ran, through the front camera, with your eyes closed and nothing on your body. Nothing is recorded. Belly versus chest is still the hand test. What it reads, and what it doesn't.

Measure your own

Two free tools, no app, no account:

And the rest of this series: cyclic sighing, how to do it and what the study found; does five minutes a day really work.

How quiettime reads your breath →

Not medical advice.