TECHNIQUES

The Physiological Sigh

Two inhales stacked, then one long exhale. The technique with the best controlled study among short breathing exercises. It is also the program's technique.

6 min read

Breathe in through the nose, add a second short inhale on top before your lungs are full, then breathe out through the mouth, long and slow. One cycle takes about ten seconds.

This is what a sigh actually is: the body already does it by itself, in sleep and during the day, minutes apart. The technique is nothing more than repeating that movement deliberately.

Why two inhales

Some of the air sacs inside the lung stay collapsed during ordinary breathing. The second short inhale, stacked on the first, opens them. That is why the second inhale must be short and must complete the first — it isn't a separate breath, it is the continuation of the same one.

The long exhale is part of it too: a long, free exhale increases the amount of carbon dioxide released and brings the body's calming side forward.

Where the evidence stands

Among the techniques in the app, this is the one with the best controlled study.

In work published by Balban and colleagues in Cell Reports Medicine in 2023, three different breathing exercises and mindfulness meditation were compared, done five minutes a day for a month. The physiological sigh came out ahead of the others in mood measures and in the drop in breathing rate.

What makes that study matter: there is a comparison group, the duration is defined and the dose is defined. Most breathing studies have none of these.

It has limits too. Participants numbered around a hundred, the period was one month, and the measures were mostly self-reported. "Doing it five minutes a day for a month showed improvement in mood measures" is a correct sentence. "The sigh takes anxiety away", on the other hand, does not come from that study.

The program in the app comes from this study

The app's 28-Day Sighing program follows that study's practice exactly: twenty-eight days, five minutes a day. You can change the length during setup, but the suggested value isn't arbitrary, it is the dose that was measured. Going below the dose isn't "doing a bit less", it is not doing the thing that was measured.

How to do the physiological sigh

Sit upright. Take a normal breath in through the nose — don't fill your lungs completely, about three-quarters.

Then add a short, sharp inhale on top. This second inhale lasts about a second and a half, clearly shorter than the first. Your lungs are now full.

Breathe out through the mouth, long and slow. About six seconds, lips slightly parted. Let the exhale go; don't push it.

In the app there is a short one-second pause between the two inhales. Other than that, there is no hold.

Common mistakes in the physiological sigh

Filling the lungs completely on the first inhale. The most common mistake. Fill completely and there is no room for the second inhale, and the technique loses its point.

Making the second inhale long. If the second inhale is the same length as the first, you have taken two separate breaths, not one stacked on another.

Cutting the exhale short. The exhale should be longer than the inhale. Cutting it short takes away most of the effect.

How the app measures the physiological sigh

The exhale is through the mouth so the sound is strong, and the thresholds match. The two inhales are measured separately: because the second is short and light, its threshold is lower still.

The report shows the second inhale on its own line. If it wasn't heard, the reason is usually the same one: the lungs were filled completely on the first inhale and there was no room for the second.

Who should take care with the physiological sigh

It is one of the gentlest techniques in the app and doesn't include a long hold. Even so, two stacked inhales is an unfamiliar movement: mild dizziness is possible in the first sessions. If it happens, stop, take a few normal breaths, then carry on.

Source

• Balban et al. (2023), Cell Reports Medicine — "Brief structured respiration practices enhance mood and reduce physiological arousal". Full text

How we weigh these sources, and what we deliberately don't claim: How we read the evidence.

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