Four techniques
Four ways to breathe.
The same physiology underlies all of them — slower exhalation, vagal activation, baroreflex resonance. The differences are about which moment you're in.
Resonance
Resonance breathing matches inhale and exhale at roughly equal length, slowing the breath to between five and seven breaths per minute. Around six breaths per minute, the baroreflex enters resonance with respiration, producing the largest possible heart rate variability swings — and, over time, raising your resting HRV.
Box breathing
Box breathing splits the breath into four equal phases: inhale four seconds, hold four, exhale four, hold four. The structure makes it impossible to breathe shallow or fast. It's not as effective at raising HRV as resonance breathing, but it's the most reliable technique for catching yourself before an escalation.
4-7-8
The 4-7-8 pattern was developed by Andrew Weil, MD, adapted from pranayama. The long exhale (twice the length of the inhale) is what does the work: extended exhalation activates the vagus nerve and pulls the nervous system into rest-and-digest. Most people feel it on the second cycle. Don't do more than four cycles in your first week — it can be surprisingly strong.
Extended exhale
Extended exhale is the underlying mechanism behind 4-7-8, behind the physiological sigh, and behind half the breathing exercises in yoga. When exhalation is longer than inhalation, heart rate slows in the exhale phase and the parasympathetic nervous system activates. We expose the mechanism directly so you can dial in your own ratio: 4 in / 6 out for daily, 4 in / 12 out for acute calm.