Nadi shodhana (alternate nostril breathing)

Breathe in through one nostril and out through the other, alternating for several rounds.

Why it works

The nasal cycle — most people’s dominant airflow naturally alternates nostrils roughly every 90 minutes — is associated with shifts in autonomic tone and cerebral blood flow lateralization. Deliberately alternating nostrils may entrain this cycle toward balance, while the slow, rhythmic nature of the practice activates baroreceptor-mediated vagal tone. The extended exhalation phase of the classic 1:2 inhale-to-exhale ratio is likely the dominant mechanism for acute calming.

How to do it

1. Sit upright. Place your right hand in Vishnu mudra: fold the index and middle fingers into the palm, leaving thumb, ring finger, and pinky extended.
2. Close the right nostril with your thumb. Inhale slowly through the left nostril for a count of 4.
3. Close both nostrils briefly (thumb + ring finger). Hold for 1–2 counts.
4. Release the right nostril and exhale fully through it for a count of 6–8.
5. Inhale through the right nostril for 4 counts, close, then exhale through the left. That is one round. Repeat 5–10 rounds.

Evidence

Several small randomized trials and controlled studies have found that nadi shodhana reduces heart rate, blood pressure, and self-reported anxiety compared to rest or control conditions. Effect sizes are generally small to moderate and studies tend to be short-term. (observational)

Most studies are small, single-session, and conducted in India with varied outcome measures. Long-term effects and comparison to other slow-breathing techniques are under-studied. Lateralization claims (left = parasympathetic, right = sympathetic) have biological plausibility but are not consistently confirmed across studies.

Common mistake

Forcing the breath ratio to make it "correct" — straining or gasping defeats the purpose. The ratio should stretch just enough to slow breathing without producing air hunger.