GoKawiilBreathe CLI
A terminal app that paces resonance breathing for vagal tone training. macOS only, single file, no dependencies.
$ breathe calm · 4-6 · 14:32 [●] INHALE ██████████████░░░░░░░░░░░░░░░░ space pause · s mute · q quit
Why this exists
Resonance breathing — slow, paced breathing at around 6 breaths per minute — is one of the few non-pharmacological interventions shown to improve cardiac vagal tone. The mechanism is straightforward: slow breathing amplifies respiratory sinus arrhythmia (RSA), the natural heart-rate variation linked to the breath cycle. Stronger RSA means stronger vagal outflow, which in turn improves baroreceptor sensitivity and shifts autonomic balance away from sympathetic dominance.
This matters most for people with heart failure with reduced ejection fraction (HFrEF), where sympathetic overdrive is both a symptom and an accelerant of disease progression. Bernardi et al. (1998) demonstrated that slow breathing at 6 bpm improves oxygen saturation and exercise tolerance in CHF patients, with effects visible after a single session. A follow-up study (Bernardi et al. 2002) showed that slow breathing also increases arterial baroreflex sensitivity in CHF — a marker strongly associated with prognosis.
This app is a habit tool that makes daily practice frictionless: open terminal, run breathe , follow the bar. It is not a medical device.
The science in brief
Why 6 breaths per minute? The cardiovascular system has a resonance frequency — typically between 4.5 and 6.5 bpm in adults — at which heart rate oscillations are maximally amplified (Vaschillo et al. 2006). Breathing at or near this frequency produces the largest RSA swings, which drive the strongest vagal training stimulus. Individual resonance frequency varies and can only be identified precisely with HRV biofeedback hardware. Without it, 6 bpm is the best population-level default: it sits at the centre of the typical range and matches the rate used in the CHF clinical trials (Bernardi et al. 1998, 2002).
Why a longer exhale in the calm and extended presets? Cardiac vagal efferent activity is gated to the respiratory cycle — vagal outflow is stronger during expiration than inspiration. A longer exhale (4s in, 6s out) extends the phase of peak vagal drive within each breath, biasing the autonomic balance further toward parasympathetic tone (Russo et al. 2017, Lehrer & Gevirtz 2014). The total cycle is still 10 seconds (6 bpm). The balanced preset uses equal timing (5-5) as a neutral baseline; the calm and extended presets use the exhale-weighted ratio for parasympathetic emphasis.
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