In 2023, Stanford University published a landmark study comparing five popular breathing and mindfulness techniques to find out which one reduced stress fastest. The winner was not meditation. It was not box breathing or 4-7-8. It was cyclic sighing — also called the physiological sigh — a simple two-part inhale followed by a long exhale.
The study, published in Cell Reports Medicine and widely discussed by neuroscientist Dr. Andrew Huberman, found that five minutes of cyclic sighing per day produced measurable improvements in mood, stress, and physiological calm — beating all other techniques tested. Here is everything you need to know about why it works and how to do it.
A physiological sigh is something your body already does spontaneously — you have done it thousands of times without thinking. Roughly every 5 minutes, your lungs automatically take a double inhale followed by a long exhale to reinflate any collapsed air sacs (alveoli). This involuntary sigh is one of your body's primary mechanisms for offloading CO₂ and resetting lung function.
Cyclic sighing takes this same breath pattern and uses it deliberately and repeatedly. The result is a powerful tool for rapidly shifting from a state of stress to a state of calm.
The 2023 Stanford study by Balban et al. randomised participants into five groups: cyclic sighing, box breathing, cyclic hyperventilation (Wim Hof style), mindfulness meditation, and a control. Each group practiced their technique for five minutes per day over four weeks.
The results were clear: cyclic sighing outperformed all other techniques on every primary stress and mood measure. Participants in the cyclic sighing group showed the greatest reductions in self-reported anxiety, the largest improvements in positive affect (mood), and the most favourable changes in heart rate variability — a key marker of nervous system balance.
Dr. Andrew Huberman popularised the physiological sigh and the study findings on his Huberman Lab podcast, bringing the technique to a mainstream audience.
The double inhale is the key. When your lungs collapse slightly under stress or during shallow breathing, no single inhale can fully re-inflate the deflated alveoli. The second sniff at the top of the inhale pops them open. This dramatically increases the surface area available for gas exchange.
The long exhale then offloads a large volume of CO₂ quickly. Because the urge to breathe is driven by rising CO₂ — not falling oxygen — exhaling fully and slowly removes the primary signal of physiological urgency. Heart rate drops, the vagus nerve is stimulated, and the feeling of calm arrives almost immediately.
Within the first few cycles, most people notice a softening of tension in the chest and shoulders. By the end of 5 minutes, heart rate is noticeably lower and the sense of mental urgency typical of stress diminishes. Some people notice a mild warmth or pleasant lightheadedness — this is normal and passes quickly.
One to three cycles is enough to interrupt an acute stress response — before a difficult conversation, when bad news hits, or when you feel anxiety rising unexpectedly. It works faster than any other single technique.
The Stanford study used a structured 5-minute daily practice. Done in the morning or at lunch, this builds a lower stress baseline over time. Participants in the study showed improvements in resting mood and calm even during non-practice hours.
Five minutes of cyclic sighing in bed, combined with gentle body relaxation, is highly effective for people whose minds race at bedtime. The rapid CO₂ offloading and parasympathetic activation make it one of the fastest ways to prepare the body for sleep onset.
Both are effective — but they serve slightly different purposes. Cyclic sighing is faster-acting and better for acute stress spikes or daily mood maintenance. Box breathing (4-4-4-4) is better for sustained focus under pressure, like during a high-stakes task or presentation. Many people use cyclic sighing to recover from stress and box breathing to prepare for demanding situations.
Five minutes is all the research requires. The lowest-friction approach is to attach it to something you already do every morning — after brushing your teeth, during your first cup of coffee, or in the shower. The technique requires no equipment, no special environment, and no prior experience with breathwork.
Unlike meditation — which many people find difficult to sustain — cyclic sighing is purely physiological. You do not have to quiet your mind or achieve a special mental state. You just breathe in a specific pattern, and the biological response follows automatically.
The Serene Breathing app includes a guided physiological sigh session with visual cues and optional haptic timing on Apple Watch — making your 5-minute daily practice effortless.
Download Free on App Store