You've probably been told, more than once, to "just breathe." It's one of those pieces of advice that sounds like a cliché until you notice that half the self-help internet, half the sports performance world, and a surprising amount of actual neuroscience are quietly in agreement that how you breathe changes how you feel within minutes. The useful question isn't whether breathwork does something. It's which pattern is worth five minutes of your day.
A 2023 Stanford trial run by Melis Yılmaz Balban and colleagues, published in Cell Reports Medicine, took that question seriously. They tested three different breathing techniques head-to-head against mindfulness meditation — same duration, same study, same wearables. One pattern came out slightly ahead on mood, and it's the one that's been getting most of the attention since: cyclic sighing, built around the "double inhale" — the physiological sigh.
What the double inhale actually is
A physiological sigh is a breath you've been taking your whole life without noticing. It's two inhales stacked back-to-back — a full breath in through the nose, then a shorter second inhale on top of it — followed by a long, extended exhale out through the mouth. Watch a dog settle before a nap, or a child who's just stopped crying, and you'll see it: the shoulders rise, rise again, then collapse on a long breath out.
The pattern was first described in the physiology literature decades before it became a wellness trend; the second inhale is thought to re-inflate alveoli that collapse slightly during normal shallow breathing, and the long exhale is where the slowdown happens. Cyclic sighing is simply the version where you do it on purpose, over and over, for a few minutes at a stretch.
What the Stanford trial actually found
The study (Balban et al., 2023) was a remote randomised controlled trial with 108 adults, mostly recruited from a Stanford undergraduate psychology class. Participants were assigned to one of four daily five-minute practices for 28 days:
| Practice | What it emphasises |
|---|---|
| Cyclic sighing | Prolonged exhalation (double inhale, long exhale) |
| Box breathing | Equal inhale, hold, exhale, hold |
| Cyclic hyperventilation with retention | Longer inhales, shorter exhales |
| Mindfulness meditation | Non-breath-focused attention control |
Everyone wore a WHOOP strap. Everyone logged mood and anxiety before and after each session. All four groups improved on daily positive affect and reduced state anxiety — meditation absolutely did something. But cyclic sighing produced a greater improvement in positive mood (p < 0.05) and a greater reduction in respiratory rate (p < 0.05) than mindfulness, and that advantage grew with more days of practice.
A few findings worth holding onto because they're easy to miss when a study gets passed around on social media:
- The effects were on state anxiety and daily mood, not trait anxiety. Nobody's underlying anxiety profile changed in a month.
- There were no significant changes in heart rate variability, resting heart rate or sleep measures in any group. The headline isn't "cyclic sighing fixes your HRV." It's "it lifts your mood today, slightly more than meditation does."
- The sample was 108 mostly young, mostly healthy adults from one university. That's a real study, but it's not a definitive one.
Why the long exhale is the part that matters
The common thread in the breath-and-stress literature isn't the inhale. It's a long, slow exhale. When you breathe out slowly, you tend to slow your heart on the exhale (the parasympathetic side of the autonomic nervous system is more active during exhalation), and over several minutes the brain seems to read that as a signal to downshift. The double inhale of a physiological sigh is doing something slightly different — topping up the lungs so the exhale that follows can be deliberately longer than normal, without feeling starved for air.
This is also why cyclic sighing beats cyclic hyperventilation on mood in the Stanford data. One has a long exhale as its whole point. The other, by design, has a shorter one.
How to do five minutes of cyclic sighing
There's no equipment, no app, no subscription. The pattern most faithful to the study's protocol:
1. Sit or lie somewhere you won't be interrupted.
2. Inhale slowly through your nose until your lungs feel comfortably full.
3. Without exhaling, take a short, sharp second inhale through your nose — just a small top-up on top of the first breath.
4. Exhale slowly through your mouth, drawing the exhale out until your lungs feel empty. Longer than the inhale, deliberately.
5. Repeat for five minutes.
Done before a meeting, during a commute (not while driving), or in the ten minutes between dinner and bed, it's one of the easier five-minute habits to actually complete. Singapore readers: this is a nice companion to a short post-dinner walk — one hits blood sugar, the other hits mood — and both cost nothing.
What it won't do
Cyclic sighing isn't a treatment for an anxiety disorder, panic disorder, or sleep apnoea, and the Stanford trial didn't study any of those. It won't magically rebuild your HRV in a week — that evidence isn't there. And one evening of it won't undo a month of five-hour sleeps. It's a small, cheap lever on how you feel in the next ten minutes, and a slightly better one than most of the alternatives you'll find on a wellness app's home screen.
If you want to go deeper into the "breath as a nervous-system dial" rabbit hole, the exhale-dominant pattern also connects to the broader research on short walks after dinner and weekend sleep recovery — the common thread being: tiny, boring interventions, consistently applied, out-perform more dramatic ones.
Pick a fixed moment — the ten minutes before bed, the walk between the car park and the office — and spend it on cyclic sighing for a week. Five minutes a day of exhale-dominant breathing has better evidence behind it than most of what the wellness internet charges you for.
