Slow, extended-exhale breathing

Breathe at about six breaths per minute with a long exhale to raise HRV in the moment.

Why it works

A longer exhale increases vagal (parasympathetic) activity, slowing the heart and raising heart-rate variability. Breathing at roughly six breaths per minute brings respiration into resonance with the natural rhythm of the cardiovascular baroreflex, which amplifies HRV — the single best-supported, most direct lever on vagal activity available to you.

How to do it

1. Inhale gently for about a count of 4, exhale for 6–8 — roughly six breaths per minute.
2. Breathe low into the belly through the nose, keeping the exhale soft and long.
3. Practice 5–10 minutes daily, not only when stressed, to train the response.
4. Let the slow exhale, not a big inhale, be the active part.

Evidence

Slow-paced breathing (~6 breaths/min) reliably raises HRV and reduces self-reported stress and anxiety across multiple studies. Heart-rate-variability biofeedback at resonance frequency has a meta-analytic base for improving stress and HRV. (rct)

The acute HRV rise is well established; whether daily practice durably raises resting "tone" is less certain. Effects are meaningful but modest, and regulate state rather than cure disorders.

Sources

• Zaccaro et al. (2018), systematic review of slow breathing and autonomic effects, Frontiers in Human Neuroscience
• Lehrer et al. / Goessl et al. (2017), meta-analysis of HRV biofeedback for stress and anxiety, Psychological Medicine

Common mistake

Forcing big, fast inhales and treating volume as the goal. The vagal lever is the slow rate and the long, soft exhale, not how much air you move.