If you have learnt Nadi Shodhana (also called Anulom Vilom) in a yoga class, you have probably heard the explanation that comes with it: breathing through alternate nostrils balances the left and right hemispheres of the brain.

It is a lovely idea. It is also testable. So I went through the research to see what it actually shows. The short version: the practice seems to calm you, but “brain balancing” is the weakest part of the story.

On the bank of the Ganga above Rishikesh.

What the practice involves

Sit upright and relax your shoulders. Close your right nostril with your right thumb and breathe in slowly through the left. Close the left nostril with your ring finger, release the thumb, and breathe out through the right. Breathe in through the right, switch, and breathe out through the left. That is one round. The breath stays slow and unforced.

This matters because some studies use “forced” nostril breathing, which is more vigorous. When you read about the research, check which version was tested.

Where the brain-balancing idea comes from

The claim is not pure mythology. It has two scientific threads.

The first is the nasal cycle. At any moment one nostril is usually more open than the other, and the dominant side shifts over time. Early EEG research found that the relative activity of the brain’s two hemispheres also alternates, and that this correlates with the nasal cycle (PMID 6874437). That is a correlation with a natural rhythm. It does not show that deliberately changing which nostril you breathe through changes your brain.

The second is a small 1994 study. Eighteen trained practitioners did ten minutes of forced alternate nostril breathing. Alpha and beta power increased, and in the second half of the session the asymmetry between hemispheres in one frequency band (beta-1) decreased. The authors described this as a balancing effect (PMID 7876041).

So the claim has a real seed. The question is whether it holds up.

What happened when researchers looked again

In a 2017 study, 13 healthy adults did three separate sessions: alternate nostril breathing, breath awareness, and quiet sitting. Hemisphere symmetry did not change during alternate nostril breathing (PMID 28738882). The research team was based at a yoga research foundation.

The studies on single-nostril breathing, which underpin the whole “left nostril, right brain” logic, do not agree with each other either. In 23 right-handed men, forcing breath through one nostril shifted the balance of verbal versus spatial performance towards the opposite hemisphere (PMID 1938166). Another study found the effects differed by sex: same-side effects in men on both tasks, and opposite-side effects in women, only for spatial tasks (PMID 2923709). A 2022 study using 64-channel EEG found that breathing through either nostril broadly reduced brain-wave power compared with rest, rather than switching on one hemisphere (PMID 35017606).

None of those three tested Nadi Shodhana directly. But they are the foundation the brain-balancing explanation rests on, and that foundation is inconsistent.

What the practice does seem to do

The better-supported story is calm.

In the same 2017 study, relative theta power fell during alternate nostril breathing and beta amplitude was lower afterwards. The authors interpreted this as greater calmness, while quiet sitting without instructions was associated with arousal (PMID 28738882).

A systematic review of randomised controlled trials published between 2013 and 2019 concluded that alternate nostril breathing reduced stress on both psychological and biological measures. Most participants in those studies were Indian and male, so we should be careful about generalising (PMID 33461386).

A 2024 meta-analysis pooled six randomised trials with 525 participants. Alternate nostril breathing lowered systolic blood pressure by about 7 mmHg and diastolic by about 5 mmHg more than control conditions (PMID 39008954). The results varied a lot between studies, and the authors themselves urge caution. It is not a substitute for blood pressure medication.

What research has not answered

We do not know whether any EEG change lasts beyond the session itself, how long or how often you need to practise, or how the effects look in women and in populations outside India. “Balance” is also not a defined measurement, which is part of why the claim is so easy to repeat and so hard to test.

How to try it

Start with a few minutes of slow, comfortable rounds. Never strain or hold your breath in a way that feels uncomfortable. If you feel dizzy or light-headed, stop and breathe normally. If you have a medical condition such as high blood pressure, keep following your doctor’s treatment; think of this practice as something you add, not something you swap in.

The takeaway

Nadi Shodhana is probably worth practising because it seems to calm you, not because it balances your brain.

Sources

1. Alternating cerebral hemispheric activity and the lateralization of autonomic nervous function. PubMed 6874437
2. EEG changes during forced alternate nostril breathing (1994). PubMed 7876041
3. Hemisphere specific EEG related to alternate nostril yoga breathing (2017). PubMed 28738882
4. The effects of unilateral forced nostril breathing on cognition (1991). PubMed 1938166
5. Unilateral nostril breathing influences lateralized cognitive performance (1989). PubMed 2923709
6. EEG signatures change during unilateral Yogi nasal breathing (2022). PubMed 35017606
7. Alternate nostril breathing to reduce stress: an option for pregnant women survivors of intimate partner violence?. PubMed 33461386
8. Effectiveness of alternative nostril breathing on blood pressure: a systematic review and meta-analysis of randomized controlled trials (2024). PubMed 39008954