I built a terminal app that paces slow breathing at 6 breaths per minute for vagal tone training. It's a single Python file, stdlib only, no dependencies — just run breathe and follow the bar.

I'm a cardiology patient (HFrEF). Slow breathing at resonance frequency is one of the few non-pharmacological interventions shown to improve cardiac vagal tone and baroreflex sensitivity (Bernardi et al., Circulation 2002; Lancet 1998). I wanted a frictionless daily habit tool — no app store, no account, no subscription, just open terminal and go.

Design constraints, all grounded in the clinical literature:

- No breath retention — Valsalva risk in cardiac patients

- No rapid breathing — minimum 8-second cycles

- Exhale ≤ 2x inhale — no evidence for extreme ratios

- Immediate exit, always — q or Ctrl+C restores the terminal even on crash

The README includes a resonance frequency measurement protocol for anyone with a chest-strap HRV monitor who wants to find their individual optimum instead of using the 6 bpm default.

macOS only (uses afplay for audio cues). MIT licensed.

pip install breathe-cli

or

brew tap marekkowalczyk/breathe && brew install breathe.

Looks interesting. And it's pure Python with no 3p packages. Pretty trivial to support other OSes: make that audio player invocation configurable.

Very nice. I have no heart issues but have been experimenting with extended breathing/longer exhales to calm down my sympathetic nervous system. I believe intentional breathing is a big, mostly underutilized tool all of us have to be generally more relaxed and healthier and also to calm ourselves down in stressful situations

This reminds me of another HRV training from few years back shared here.

- https://news.ycombinator.com/item?id=37538028

- https://github.com/kieranabrennan/every-breath-you-take

Terminally breathing