The physiological sigh: how to do it and why it works
If I could teach you only one breath, it would be this one. Two inhales, one long exhale, and about fifteen seconds to feel a shift.
The short answer. A physiological sigh is a double inhale through the nose followed by a long exhale through the mouth. One to three sighs can take the edge off a stressful moment, and research suggests five minutes a day may support better mood.
What is a physiological sigh
You already do it. Everyone sighs spontaneously several times an hour, often without noticing, and more often under stress or when you are about to fall asleep. Researchers have mapped the small brainstem circuit that generates sighs in mice (Li 2016). The practice I teach simply takes that natural reflex and uses it on purpose.
Curious why your body sighs on its own, and why screens may quietly cut those sighs? Read A Sigh, But Why?
How to do it
- Inhale through your nose until your lungs feel comfortably full.
- Take a second, short inhale through your nose on top of the first, a little sip to fill the last space.
- Exhale slowly through your mouth until your lungs feel empty. Make the exhale clearly longer than both inhales together.
- Repeat one to three times, then return to easy breathing through your nose.
Want it as a daily practice? Keep repeating it at your own pace for five minutes. That is cyclic sighing.
Why it seems to work
Two things are happening. The double inhale helps fully inflate the lungs, including small air sacs that tend to partially collapse over time, which is one reason the body sighs spontaneously. Then the long exhale engages the slowing side of the heart rhythm: heart rate tends to ease on the out-breath, and slow, exhale-led breathing is linked with greater parasympathetic activity (Russo 2017; Zaccaro 2018).
What the research says
The clearest human data comes from a one-month randomized study at Stanford. Participants practiced five minutes a day of cyclic sighing, box breathing, cyclic hyperventilation or mindfulness meditation. The cyclic sighing group showed the largest daily improvement in positive mood and a lower resting breathing rate, and breathing practices overall improved mood more than mindfulness (Balban 2023). It is one study with healthy volunteers, so I describe it as promising rather than proven.
When I use it
- Before I walk on stage or into a hard conversation.
- Standing at the edge of a cold plunge, before the long exhale in. My cold plunge breathing guide shows the full sequence.
- Lying in bed when my mind is still running.
- Any time I notice my shoulders creeping toward my ears.
Common mistakes
- Rushing the exhale. The long, slow exhale is the point. Take your time.
- Forcing the second inhale. It is a small top-up, not a gasp.
- Doing dozens in a row quickly. That becomes over-breathing and can leave you lightheaded. Keep a calm pace.
Please practice safely. This is education, not medical advice. Never practice breath holds or breathing exercises in or near water, while driving, or anywhere fainting could hurt you. Cold water carries real risk: never plunge alone, and speak with your doctor first if you are pregnant or have a heart condition, high blood pressure, epilepsy, Raynaud's or any other medical condition.
The sigh is one tool in a bigger practice. Read breathing for nervous system regulation for a full daily routine, the breathwork guide for the science, and visit the library for my World Breathing Day conversation with Dr. Andrew Huberman on the science of stress and breathing.
Questions people ask me
What is a physiological sigh?
A physiological sigh is a breath with two inhales, a full one followed by a short top-up, and then one long, slow exhale. Humans and other mammals sigh spontaneously several times an hour, and the deliberate version is one of the quickest ways I know to shift your state.
How do you do a physiological sigh?
Breathe in deeply through your nose. Without exhaling, take a second short sip of air through your nose to fill your lungs fully. Then exhale slowly through your mouth until your lungs feel empty. Repeat one to three times, or practice it continuously for five minutes as cyclic sighing.
Does the physiological sigh reduce stress?
Research suggests it may help. In a one-month randomized study, five minutes a day of cyclic sighing was linked with improved mood and a lower resting breathing rate, with larger daily mood gains than mindfulness meditation.
How many physiological sighs should I do?
In a stressful moment, one to three are often enough. As a daily practice, five minutes of cyclic sighing was the dose used in the Stanford study.
Who discovered the physiological sigh?
Physiologists have studied sighing for decades. Research in mice published in Nature in 2016 identified the brainstem circuit that generates sighs, and the deliberate practice was later studied in people at Stanford.
Practice it with me
My free 10-minute guided session walks you through the sigh and a full breathing practice.
References
- Li et al. (2016). The peptidergic control circuit for sighing. Nature. doi.org/10.1038/nature16964
- Balban et al. (2023). Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. doi.org/10.1016/j.xcrm.2022.100895
- Zaccaro et al. (2018). How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Frontiers in Human Neuroscience. doi.org/10.3389/fnhum.2018.00353
- Russo et al. (2017). The physiological effects of slow breathing in the healthy human. Breathe. doi.org/10.1183/20734735.009817
The Practice
Make it daily.
Guided breath, cold and deep rest sessions in your podcast app, with a new one every month. Nine sessions to start, from a 6-minute reset to a 56-minute journey.
Practice breathwork seated or lying down, never in or near water or while driving.