“Cardiac coherence” (cohérence cardiaque) is the popular name of this breathing practice, especially in France: slow, even breathing — usually about six breaths per minute — used to shift the autonomic nervous system toward calm. In physiology, the term describes the smooth, regular heart rhythm that slow breathing tends to produce. Its best-known form, popular in France, is the 365 method: 3 times a day, 6 breaths per minute, for 5 minutes. Slow breathing at around six breaths per minute reliably raises heart rate variability (HRV) during practice, and HRV-biofeedback trials show modest benefits for stress and anxiety — but the specific "three times a day" schedule is a practical convention, not a protocol that has been tested against alternatives.
What is cardiac coherence?
Cardiac coherence is the smooth, wave-like heart rhythm that appears when you breathe slowly and evenly. Your heart rate naturally rises on the inhale and falls on the exhale (respiratory sinus arrhythmia). At around six breaths per minute this swing becomes large and regular, and heart-rate and blood-pressure rhythms oscillate together — the same harmony-of-rhythms idea, given a simple daily protocol. English-language sources usually call the practice coherent or resonance breathing.
Physiologically, the result is a large rise in HRV while you breathe this way, driven mainly by the parasympathetic ("brake") branch and the baroreflex. Subjectively, most people describe it as calm and clear-headed.
What is the 365 method?
The 365 method is a daily schedule for cardiac coherence, popularized in France by the physician David O’Hare:
| Number | Meaning | In practice |
|---|---|---|
| 3 | Three sessions a day | Morning, around midday, late afternoon or evening |
| 6 | Six breaths per minute | About 5 seconds in, 5 seconds out |
| 5 | Five minutes per session | Roughly 30 slow breaths |
The rationale is that the calming effect of one session is real but short-lived, so spacing sessions keeps bringing the nervous system back toward balance. That reasoning is sensible, but no trial has compared "3 × 5 minutes" with, say, one 15-minute session or twice-daily practice. HRV-biofeedback studies typically use around 20 minutes of daily practice, sometimes split into sessions, so the 365 method sits in a reasonable range rather than being a proven optimum.
Why six breaths a minute?
Six breaths a minute is close to the average resonance frequency of the cardiovascular system — about 0.1 Hz — where breathing, heart rate, and the baroreflex reinforce one another and HRV swings are largest (Lehrer & Gevirtz, 2014). The exact resonance rate varies between people, roughly 4.5 to 7 breaths per minute, so it's worth finding your own resonance rate rather than treating six as magic.
A 2022 meta-analysis (Laborde et al., Neuroscience & Biobehavioral Reviews) found that voluntary slow breathing below about 10 breaths per minute increases vagally mediated HRV during the practice, with immediate effects that are robust; evidence for lasting changes after practice is weaker. A broader meta-analysis of HRV biofeedback (Lehrer et al., 2020) reported small-to-moderate improvements across outcomes such as anxiety, stress, and depressive symptoms, though study quality varies. Longer exhales than inhales are commonly recommended for comfort and calm, but most of the measured effect comes from the slow rate itself.
What does the evidence show — and not show?
| Claim | Evidence |
|---|---|
| Slow breathing near 6/min raises HRV during practice | Strong (meta-analysis) |
| Regular HRV biofeedback reduces stress and anxiety | Moderate; small-to-moderate effects, mixed study quality |
| Effects persist hours after a 5-minute session | Limited; short-term carry-over is plausible but poorly quantified |
| The 3 × 6 × 5 schedule is optimal | Not tested; a practical convention |
How do you practice cardiac coherence?
- •Sit upright and comfortable, eyes open or closed.
- •Breathe in for about 5 seconds and out for about 5 seconds — six breaths per minute. A visual guide or timer helps at first.
- •Keep the breath smooth and unforced, through the nose if comfortable; let the exhale be complete.
- •Continue for 5 minutes, up to three times a day. Regularity matters more than intensity. If sleep is the issue, make one session an evening one — see cardiac coherence for insomnia.
- •Don't strain. If five seconds feels long, start a little faster and slow down as it becomes comfortable.
For comparison with other paced techniques, see 4-7-8 breathing.
Safety: when should you stop?
Stop and breathe normally if you feel dizzy, light-headed, short of breath, tingly, or panicky — usually a sign of breathing too deeply. Breathe gently rather than taking huge breaths. If you have a heart or lung condition (including arrhythmia, heart failure, asthma, or COPD), low blood pressure, a history of panic attacks, or are pregnant, keep sessions gentle and check with your clinician. Cardiac coherence is a self-care practice, not a substitute for medical treatment.
See your own rhythm
Because cardiac coherence is a measurable state, it's useful to watch it. ONDA’s guided breathing sessions read your pulse and an estimated breathing rate from your iPhone camera, or from your Apple Watch, so you can see your heart rate rise and fall with your breath in real time. With an Apple Watch, ONDA also shows a live coherence reading (the camera shows pulse and breathing only). ONDA guides breathing with text, audio, and visuals rather than a fixed metronome, so keep your own 5-second count or timer if you follow the 365 method strictly.