Breath Practices: What They Are and What the Evidence Says

Breath regulation is one of the older components of yoga, described in texts long before the modern posture practice existed. It covers a wide range of techniques, and they are not all doing the same thing or supported by the same evidence.

What the traditional practices involve

Broadly, three categories.

Slowing and lengthening the breath, often with the exhalation longer than the inhalation, sometimes with pauses. This is the largest group and includes most of what is taught in general classes.

Altering the pattern, such as breathing through alternate nostrils, or breathing with a slight constriction at the throat that produces an audible sound.

Rapid or forceful breathing, such as practices involving quick forceful exhalations. These are a different category with different effects and different risks.

Classical texts also describe breath retention, sometimes for extended periods, generally as an advanced practice undertaken with a teacher.

What the evidence supports

Slow breathing affects the autonomic nervous system. This is the best-established finding. Breathing at around six breaths per minute, and extending the exhalation relative to the inhalation, increases heart rate variability and shifts the balance toward parasympathetic activity. It is measurable and reasonably consistent across studies.

The mechanism is reasonably well understood and involves the relationship between breathing and heart rate, and the effect of lung stretch receptors on the vagus nerve. The exhalation matters more than the inhalation.

Slow breathing reduces self-reported anxiety and stress in the short term. Reasonable evidence, with the usual caveat that participants know what they are doing.

Slow breathing has modest effects on blood pressure in some studies, though the size and durability are debated.

What is less well supported

Specific claims for specific techniques. The idea that alternate nostril breathing does something distinct and identifiable that ordinary slow breathing does not is not well established. Most studies are small and comparisons against a matched slow-breathing control are rare.

Claims about detoxification, oxygenation and energy. Normal breathing already saturates arterial blood with oxygen nearly completely. You cannot meaningfully increase blood oxygen by breathing harder, and breathing more than your body needs lowers carbon dioxide rather than raising oxygen, which produces the lightheadedness people sometimes mistake for an effect.

Dramatic claims about immune function or disease. Some studies exist and are generally small and preliminary. Treat confident claims here with scepticism.

Where genuine caution is warranted

Rapid or forceful breathing practices lower carbon dioxide and can cause dizziness, tingling and fainting. They are generally not recommended during pregnancy, with uncontrolled high blood pressure, with epilepsy, with a history of fainting, or with certain heart or eye conditions. Learning them from a video without supervision is not a good idea.

Breath retention should not be practised in or near water under any circumstances. Hyperventilation followed by breath-holding is genuinely dangerous and has caused deaths, including in experienced practitioners.

If a practice makes you dizzy, tingly or panicky, stop. These are not signs of progress.

Anyone with a respiratory condition, a heart condition, uncontrolled blood pressure, or who is pregnant should take advice before taking up forceful practices.

What is worth doing

For most people, the useful practice is also the simplest: sit or lie comfortably, breathe through the nose, and make the exhalation about twice as long as the inhalation. Five minutes. No retention, no force.

That is the technique with the best evidence and essentially no risk, and it is available immediately.

Where a teacher helps

Mostly with the forceful practices, which should not be self-taught, and with noticing when someone is straining. Breath practice done with effort produces the opposite of the intended effect, and people frequently cannot tell they are forcing it.

Sessions are live on video, thirty or sixty minutes, with a teacher in India.

Questions people ask

Does pranayama actually do anything?

Slow breathing has well-established effects on the autonomic nervous system, measurable as increased heart rate variability, and reasonable evidence for short-term reductions in anxiety. Claims specific to individual named techniques are much less well supported.

Which breathing technique is best?

For most purposes, slow nasal breathing with the exhalation about twice as long as the inhalation. It has the best evidence, essentially no risk, and requires no instruction to begin.

Can breathing exercises increase my oxygen levels?

Not meaningfully. Normal breathing already saturates arterial blood with oxygen almost completely. Breathing harder mainly lowers carbon dioxide, which causes the lightheadedness sometimes mistaken for a beneficial effect.

Are any breath practices risky?

Rapid or forceful techniques can cause dizziness and fainting and are generally avoided in pregnancy, epilepsy, uncontrolled blood pressure and some heart conditions. Breath retention should never be practised in or near water.