Physiological Sigh
A physiological sigh is two breaths in through the nose, the second one short, followed by one long breath out through the mouth [1]. In a trial of 108 people, 5 minutes a day of this "cyclic sighing" for a month lifted mood more than mindfulness did. Anxiety fell about as much in both groups.
In short
- What it is
- Two sips of air in through the nose, one long breath out.
- One sigh
- About 10 seconds at our pace, so 6 a minute.
- What trials found
- Mood and breathing rate improved. Anxiety did not beat mindfulness.
- Who should be careful
- Stop if dizzy. With heart or lung disease, ask your doctor first.
Breathe in 2 · Sip in 1 · Breathe out 6 · Rest 1
Take the second breath small. Never strain. If you feel dizzy or tingly, stop and breathe normally.
At the standard pace one sigh takes 10 seconds, so 5 minutes is about 30 sighs. The circle grows on the first breath, grows a little more on the sip, shrinks slowly on the breath out and stays small during the rest. The seconds are ours: the studies did not time the breath.
Quietarium editorial team Updated Sources: 15
How to do a physiological sigh
Breathe in through your nose, sip a little more air in on top, then let it all out slowly through your mouth. The trial protocol says to "inhale again once more to maximally fill the lungs," and adds "even if the second inhale was shorter in duration and smaller in volume" [1].
- Breathe in slowly through your nose until your lungs feel nearly full.
- Sip in a second, shorter breath on top, also through your nose. Think of topping off a glass.
- Breathe out slowly through your mouth, all the way, for longer than either breath in. Rest a beat and start again.
If breathing out through your mouth feels odd, use your nose. The trial allowed that [1]. Keep the second sip small. If it hurts or makes you dizzy, skip it and just breathe out slowly.
How many sighs, and for how long?
Thirty seconds before a hard phone call is enough for 3 sighs. That is a common quick use, and no trial has tested it. The trial that did test a daily practice used 5 minutes [1].
| Mode | Length | Evidence | Use |
|---|---|---|---|
| 3 sighs | about 30 seconds | No trial tested this dose. A Stanford psychiatrist says "after one or two of these deep sighs, you may already feel calmer," which is an opinion [2]. | A quick reset at your desk |
| 1 minute | about 6 sighs | One pilot of 47 students in real stressful situations: anxiety fell more than with a passive control [3]. | Before a hard moment |
| 5 minutes | about 30 sighs | The one-month trial used 5 minutes a day [1]. A 4-minute session in a clinic waiting room lowered pain ratings [4]. | A daily practice |
Pick the Length in the timer: 3 sighs, 1 minute or 5 minutes. A minute at the standard pace is about 6 sighs.
How long should each part last?
The studies did not time the breath, so the seconds in our timer are ours. The trial's instructions give the order of the breaths and no counts [1].
Our standard pace is 2 seconds in, 1 second for the sip, 6 seconds out and 1 second of rest. The breath out is the longest part because the trial's abstract describes cyclic sighing as the version that "emphasizes prolonged exhalations" [1]. If 6 seconds feels short, switch the timer to 3 · 1 · 7 · 1.
The arithmetic is simple. One sigh at the standard pace takes 2 + 1 + 6 + 1 = 10 seconds, which gives 6 sighs a minute. At the slower pace one sigh takes 12 seconds, or 5 a minute. Five minutes is about 30 sighs at the standard pace and 25 at the slower one.
Does the physiological sigh work? What the studies found
In small trials it lifted mood and slowed breathing, but it did not lower anxiety more than mindfulness meditation did [1]. The table lists what each study found and what it left open.
| Study | Who and how | What it found | What it did not show |
|---|---|---|---|
| Balban 2023 [1] | 108 randomized: mindfulness 24, cyclic sighing 30, box breathing 21, cyclic hyperventilation 33. Healthy adults, mostly Stanford students. Done remotely, 5 minutes a day for 28 days. | Breathwork beat mindfulness for daily positive mood. Only cyclic sighing did so on its own: +1.89 vs +1.22 points on a 10‑50 scale. Resting breathing rate was lower with sighing. | State anxiety and negative mood did not differ from mindfulness. Heart rate, heart rate variability, sleep and trait anxiety did not change. No effect sizes, registered after the study began, self-reported adherence, no follow-up. |
| Riedl 2026 [3] | Pilot, 47 students, 1 minute in real stressful situations. Sighing vs box vs a passive control. | Sighing and box both cut state anxiety more than the passive control. | Reaction times were longer afterward. The abstract names no winner between sighing and box. |
| Hanley 2025 [4] | Pilot randomized trial in an orthopedic clinic waiting room. 4 minutes vs an injury-care control. | Less pain unpleasantness and less pain intensity. | Anxiety and depression symptoms did not differ. The abstract gives no head count. |
| Jones 2026 [5] | Randomized trial, 62 cadets after maximal exercise. Sighing, box or spontaneous breathing. | Sighing and box both raised high-frequency heart rate variability more than spontaneous breathing between the two recovery windows. | Heart rate recovery did not differ between groups. Fit young adults only. |
| Vlemincx 2016 [6] | Lab experiment on deep breaths. | Self-reported relief was higher after an instructed deep breath. | One breath, not the exercise. The abstract gives no head count. |
| Muzumdar 2026 [7] | 250 healthy students took one sigh every 30 or every 15 seconds. | Each pace raised heart rate and blood pressure, a pattern the authors call sympathetic activation. | The study built a stress test. It did not test relaxation or the full exercise. |
The senior author of the main trial, Huberman, became an advisor to the wearable company WHOOP in June 2022. WHOOP donated the straps that measured breathing rate and, per the paper, took no part in design or analysis [1].
Put together, the sigh looks like a short mood and breathing-rate reset in small, short trials, and none of them tested it as therapy. The mood gap was +1.89 vs +1.22 points on a 10‑50 scale, about 0.7 of a point.
Cyclic sighing vs physiological sigh: are they the same?
Mostly yes. "Cyclic sighing" is the name in the trials, "physiological sigh" is the popular one, and the main trial paper never uses the second [1].
A spontaneous sigh is a deeper breath your body adds by itself. The exercise is a deliberate version, repeated for minutes. Researchers have proposed that the spontaneous kind acts as a reset:
Sighing is hypothesized to function as a resetter in the regulation of both breathing and emotions [8].
That is a hypothesis from a review. Nobody has tested it on the exercise.
Physiological sigh vs box breathing vs a longer exhale
No trial shows that any of the three is best. In the one direct test, a 1-minute pilot, sighing and box both cut anxiety more than doing nothing [3].
| Physiological sigh | Box 4‑4‑4‑4 | Longer exhale (4 in, 6 out) | |
|---|---|---|---|
| Holds | None. A second sip instead. | Two. | None. |
| Pace (ours) | About 6 sighs a minute | 3.75 rounds a minute | 6 breaths a minute |
| Best human evidence | Balban: better mood and lower breathing rate than mindfulness [1] | McAllister, 66 people: a smaller rise in heart rate, anxiety and a saliva stress marker before a stress test [9] | Marchant, 84 students: 6 breaths a minute raised heart rate variability more than square or 4‑7‑8 breathing, with no change in mood or blood pressure [10] |
| Against each other | Riedl: sighing and box both beat a passive control [3]. Jones: both raised heart rate variability more than spontaneous breathing [5]. | Same two studies. | Not tested against sighing in the studies above. |
| Watch out for | Each deliberate big breath briefly raises heart rate and blood pressure [7]. | After hard interval exercise, box gave a higher heart rate than 6 breaths a minute [11]. | Marchant noted mild over-breathing at this pace [10]. |
In Balban, box breathing and sighing lifted mood by about the same amount (+1.84 and +1.89 points). Only sighing beat mindfulness on its own, and the groups were too small to compare the breathing methods with each other [1]. The box side of this table is covered in box breathing and what it showed. To try the longer exhale with a timer, use the page on how to calm your nervous system. There is also a page on 4-7-8 breathing, and one on belly breathing for a gentler start.
Does the physiological sigh open your alveoli?
"Doesn't the second breath pop open the air sacs?" Maybe, but nobody has shown it for the exercise.
| Said online | What we found |
|---|---|
| The second inhale pops open collapsed air sacs (alveoli). | Spontaneous sighs are thought to keep the air sacs from collapsing, according to reviews [12][13] and work in mice [14]. Nobody has measured it for the deliberate double inhale. The Balban paper does not mention alveoli. |
| Stress makes your alveoli collapse. | We found no human study showing this in healthy people. |
| It sends more oxygen to the brain and clears CO₂. | The trial measured neither oxygen nor CO₂ [1]. |
| It lowers cortisol and activates the vagus nerve. | The trial did not measure cortisol, and heart rate variability and resting heart rate did not change [1]. |
Until someone measures it, read any page that states the alveoli story as fact with doubt.
Physiological sigh for anxiety and panic
In a panic, start with a slow breath out and skip the counting. The sigh can take the edge off a tense moment, but no trial has tested it on people with an anxiety or panic disorder.
The main trial found no difference in state anxiety between the breathing groups and mindfulness. Daily change in the sighing group was -3.85 points on a 20‑80 scale, against -3.95 for mindfulness [1]. The 1-minute pilot did find a larger drop than a passive control, in students facing real stress [3]. In the waiting-room trial, pain ratings fell and anxiety symptoms did not differ [4].
Across breathwork of every kind, a 2023 meta-analysis put the anxiety effect at g = -0.32, which is small. That pools many methods, so it says little about the sigh alone [15]. The trials above enrolled healthy adults, students and clinic patients. Balban excluded people with moderate to severe psychiatric conditions [1]. If focusing on your breath makes things worse, switch your attention outward with 5-4-3-2-1 grounding.
Who should be careful with the physiological sigh?
For a healthy adult it is a low-stakes exercise. The studies we read name no specific danger for this exercise, so the list below is cautious sense and not tested rules.
- If your head swims or your fingers tingle, you are probably breathing too hard. Stop and breathe at your usual pace.
- If the second sip hurts or you have to strain, make it smaller. The trial allowed a second inhale that was smaller and shorter [1].
- If you sigh quickly for several minutes, expect a faster heartbeat. Deliberate big breaths every 15 to 30 seconds briefly raised heart rate and blood pressure in healthy students [7]. Keep the pace slow.
- If you have heart or lung disease, glaucoma, seizures or a history of psychosis or bipolar disorder, or you are pregnant, ask your doctor first. Balban left these groups out [1]. That was a screening rule for the study, not a proven risk.
Frequently asked questions
Can I do the physiological sigh before bed?
You can, though the main trial gives no reason to expect better sleep: sleep measured by a wearable and by questionnaires did not change over the month [1]. For bedtime, the slower 3 · 1 · 7 · 1 pace is the gentler choice.
Is it the same as deep breathing?
Not quite. Deep breathing is one large breath. The sigh adds a second small sip on top before a long breath out. A lab study found that people reported more relief after a single instructed deep breath [6], but that was one breath, not the exercise.
Can kids do it?
Do it together with an adult, keep it short and make it a game. The trial we cite enrolled adults [1], so we have no tested doses for children.
Why does the second breath feel smaller?
Your lungs are already nearly full after the first breath in. The trial instructions expect this: the second inhale may be "shorter in duration and smaller in volume" [1].
When to see a professional
A breathing exercise cannot tell you why you feel the way you do. Make an appointment with a doctor or therapist if:
- worry or panic is part of most of your days, for several weeks;
- you avoid places or people because you fear another panic attack;
- the sighs leave you light-headed again and again;
- you have chest pain, fainting or a racing heart that does not settle. Get medical care for that instead of trying another round.
This page is general information, not medical advice.
Drop the second sip and breathe the way you normally do. Put both feet on the floor and name three things you can see.
If you feel very bad right now
Emergency, US and Canada 911
If you are thinking about suicide or are afraid you might hurt yourself, call or text now. You do not have to wait until it gets worse.
- Updated
This page does not replace advice from a doctor. Medical disclaimer · Editorial policy
Sources: 15
- Balban MY, Neri E, Kogon MM, et al. Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Rep Med. 2023;4(1):100895. doi:10.1016/j.xcrm.2022.100895. PubMed 36630953. Randomized trial.
- Leggett H. Cyclic sighing can help breathe away anxiety. Stanford Medicine News, February 9, 2023. med.stanford.edu (accessed October 19, 2026). Cited for an expert's opinion only. News release.
- Riedl EM, Bracklo T, Wimmer K, Perzl J. Simply breathing anxiety away? A pilot, just-in-time ecological momentary intervention study of one-minute cyclic sighing versus box breathing as tools for acute anxiety reduction and attention promotion in real life. Anxiety Stress Coping. 2026;39(5):608-622. doi:10.1080/10615806.2026.2659809. PubMed 42002307. Pilot trial.
- Hanley A, Davis A, Worts P, Pratscher S. Cyclic sighing in the clinic waiting room may decrease pain: results from a pilot randomized controlled trial. J Behav Med. 2025. doi:10.1007/s10865-024-00548-5. PubMed 39904867. Pilot trial.
- Jones M, Smith G, Acevedo A, Melton B. Effectiveness of structured breathwork interventions on heart rate variability and heart rate recovery following maximal exertion in tactical athletes. Med Sci Sports Exerc. 2026. doi:10.1249/MSS.0000000000003972. PubMed 41839180. Randomized trial.
- Vlemincx E, Van Diest I, Van den Bergh O. A sigh of relief or a sigh to relieve: the psychological and physiological relief effect of deep breaths. Physiol Behav. 2016;165:127-135. doi:10.1016/j.physbeh.2016.07.004. PubMed 27404329. Lab study.
- Muzumdar N, Sun K, Zhang S, Piersol K, et al. Dissecting cardiovascular responses to a fixed-interval volitional sighing protocol using a mixed modeling approach. Psychophysiology. 2026. doi:10.1111/psyp.70235. PubMed 41546440. Lab study.
- Vlemincx E, Abelson JL, et al. Respiratory variability and sighing: a psychophysiological reset model. Biol Psychol. 2013;93(1):24-32. doi:10.1016/j.biopsycho.2012.12.001. PubMed 23261937. Review.
- McAllister MJ, Martaindale MH, Sutton N, Andersen JP. Box breathing and prolonged exhalation reduces markers of physiological stress reactivity in response to a virtual trier social stress test. Compr Psychoneuroendocrinol. 2026;27:100360. doi:10.1016/j.cpnec.2026.100360. PubMed 42388906. Randomized trial.
- Marchant J, Khazan I, Cressman M, Steffen P. Comparing the effects of square, 4-7-8, and 6 breaths-per-minute breathing conditions on heart rate variability, CO2 levels, and mood. Appl Psychophysiol Biofeedback. 2025;50(2):261-276. doi:10.1007/s10484-025-09688-z. PubMed 39864026. Repeated-measures trial.
- Kasap M, Aydin GR. Box breathing or six breaths per minute: which strategy improves athletes post-HIIT cardiovascular recovery? PLoS One. 2025;20(11):e0336615. doi:10.1371/journal.pone.0336615. PubMed 41248139. Crossover trial.
- Severs L, Vlemincx E, Ramirez J. The psychophysiology of the sigh: I: The sigh from the physiological perspective. Biol Psychol. 2022. doi:10.1016/j.biopsycho.2022.108313. PubMed 35288214. Review.
- Ramirez J, Vlemincx E, Baertsch N, Severs L. The sigh and related behaviors. Handb Clin Neurol. 2022. doi:10.1016/B978-0-323-91534-2.00015-1. PubMed 35965032. Review.
- Li P, Janczewski WA, Yackle K, et al. The peptidergic control circuit for sighing. Nature. 2016;530(7590):293-297. doi:10.1038/nature16964. PubMed 26855425. Animal study.
- Fincham GW, Strauss C, Montero-Marin J, Cavanagh K. Effect of breathwork on stress and mental health: a meta-analysis of randomised-controlled trials. Sci Rep. 2023;13:432. doi:10.1038/s41598-022-27247-y. PubMed 36624160. Meta-analysis.