Where it comes from
Physiological sighs occur naturally every five minutes or so, especially during sleep — they reopen collapsed alveoli (small air sacs) and restore lung function.
Why it works so fast
The double inhale fully inflates the lungs, including under-ventilated alveoli. The long exhale offloads CO₂ and slows heart rate via the vagus nerve. The result: measurable calm in under 60 seconds.
The Stanford study
Balban et al., Cell Reports Medicine 2023: five minutes a day of cyclic sighing reduced anxiety and respiratory rate more than meditation in a randomised trial of 108 people.
The protocol
Two short inhales through the nose (one big, then a top-up sniff). One long, slow exhale through the mouth. Repeat for 5 minutes. Once a day, or whenever needed acutely.
Log your sessions in Breathe On and explore the matching guidance at [/breathing-for/stress](/breathing-for/stress).