TECHNIQUES

Cooling Breath

Air drawn between the teeth leaves a coolness in the mouth. Tradition calls it "cooling", but measurement doesn't bear that out — we write both.

5 min read

Close your teeth lightly together and part your lips. Draw air slowly through that narrow gap for four seconds. Then close your mouth and breathe out through the nose over six seconds.

The sound happens only on the inhale: a soft hiss. The exhale is silent.

What happens

When air passes through a narrow gap, the inhale slows by itself — you get a long inhale without having to force it.

Second, as the air passes through your wet mouth there is evaporation, and that leaves a clear coolness. You feel it on your teeth and on your tongue.

The "cooling" question

The classical texts describe this technique as cooling. In a study of seventeen people, body temperature was measured and it did not drop; it rose slightly.

So the coolness you feel in your mouth is a real sensation, but it isn't cooling your body.

That it feels good on a hot day or when you are angry may come from that sensation and from the slowed breathing. We have no more than a single study with a small number of participants.

How to do the cooling breath

Close your teeth lightly — don't clench, just let them touch. Part your lips as if smiling, leaving a thin gap between the teeth.

Draw air slowly through that gap for four seconds. You'll hear a hiss.

Close your mouth and breathe out through the nose for six seconds.

The version with the tongue

If you can curl your tongue into a tube and put its tip out between your lips, you can do the same thing with the tongue. Because the gap is narrower, the coolness feels a little stronger — classically called Sitali.

Not everyone's tongue curls; that is inherited. If yours doesn't, don't worry about it: the version with the teeth is the same technique, and it is the one the app is built around.

Common mistakes in the cooling breath

Drawing the air in fast. Drawing fast dries the throat and brings on a cough. Draw slowly.

Clenching the teeth. Touching is enough; keep your jaw loose.

Breathing out through the mouth. The exhale is always through the nose, mouth closed.

Doing it in very cold air. Don't do it outdoors in winter or in front of an air conditioner.

How the app measures the cooling breath

This technique reverses the usual arrangement in the app: the noise is on the inhale and the exhale is silent.

In the other techniques the exhale is strong and the inhale is low. Here it is exactly the other way round: the app uses a lower threshold so it can hear the silent exhale too, and takes its real measurement from the hiss of the inhale.

In the report a separate component appears under the name Hiss: how clearly the hiss is heard on each inhale and how long it lasts through the inhale. A large part of the score comes from this component. Even when the hiss is faint, rhythm and exhales earn their own share.

Who should take care with the cooling breath

If you have asthma or are sensitive to cold, be careful: cold, dry air can irritate the airways. The app shows this warning before the session.

When your throat dries out, take a break and drink some water.

Sources

• Hatha Yoga Pradipika (15th century, chapter 2) — verse 54 describes the version with the teeth, verses 57-58 the one with the tongue.
• Telles et al. (2020), Medical Science Monitor Basic Research — body temperature, oxygen consumption and carbon dioxide output measured in seventeen people; temperature did not drop. PubMed

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

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