5-5 breathing (five in, five out)

Breathe in for five seconds and out for five seconds, continuously, for five to twenty minutes.

Why it works

At five breaths per minute (0.1 Hz), respiratory sinus arrhythmia — the natural heart-rate acceleration during inhalation and deceleration during exhalation — synchronizes with the body’s blood-pressure regulation loop (the Mayer wave). This synchrony amplifies HRV amplitude dramatically compared to uncontrolled breathing, strengthens baroreflex gain, and measurably increases parasympathetic tone. The "five seconds each" instruction is the simplest approximation; individual resonance frequencies cluster near but not exactly at this rate.

How to do it

1. Sit comfortably, close your eyes, and breathe through the nose.
2. Inhale for a slow count of five (roughly five seconds), expanding the belly first.
3. Exhale for a slow count of five — do not rush; let it empty naturally.
4. Use an app pacer (a moving dot or bar) to maintain the rhythm without counting internally.
5. Practice for at least five minutes; twenty minutes produces more reliable baseline shifts.

Evidence

Breathing at 5–6 cycles per minute robustly increases HRV amplitude and baroreflex sensitivity in controlled studies. Meta-analyses confirm reductions in self-reported anxiety and stress with regular slow-breathing practice. Resonance-frequency breathing at this rate — formalized in Lehrer’s training protocol and corroborated by Steffen et al. — is what drives the large-amplitude HRV, blood-pressure, and mood effects rather than slow breathing in general. (rct)

Coherence effects are real but acute — they occur during and briefly after practice. Long-term baseline improvements require sustained daily practice over weeks and are supported by observational data rather than long-duration RCTs.

Sources

• Zaccaro et al. (2018), systematic review of slow breathing and autonomic/CNS effects, Frontiers in Human Neuroscience
• Lehrer & Gevirtz (2014), HRV biofeedback: how and why it works, Frontiers in Psychology
• Lehrer PM, Vaschillo E, Vaschillo B. (2000). Resonant Frequency Biofeedback Training to Increase Cardiac Variability: Rationale and Manual for Training. Applied Psychophysiology and Biofeedback, 25(3), 177-191.
• Steffen PR, Austin T, DeBarros A, Brown T. (2017). The Impact of Resonance Frequency Breathing on Measures of Heart Rate Variability, Blood Pressure, and Mood. Frontiers in Public Health, 5, 222.

Common mistake

Counting too quickly — if five seconds does not feel genuinely slow, the breath rate is too high. Count "one-one-thousand, two-one-thousand" rather than rapid numeric ticks.