Resonance Breath

Open the app, tap once, and breathe. A sun grows as you breathe in and shrinks as you breathe out, while a soft tone rises and falls on exactly the same clock. Match your breath to the sun. That is the whole app.

Why this pace

Your heart speeds up a little as you breathe in and slows as you breathe out. Breathing slowly — about five to six breaths a minute — makes that rise and fall as large and smooth as it can be.

That swing is your heart rate variability, or HRV. A higher, steadier HRV is one of the clearest signs of a nervous system that copes well with stress, and this pace of breathing — studied as resonance-frequency breathing, or HRV biofeedback — is one of the most reliable ways to raise it.

Ten minutes a day for five to six weeks lifts your resting HRV. In studies, breathing like this has helped people feel calmer, sleep better, and stay steadier under pressure. The app links to the research it's built on, so you can read it yourself.

What it does

• A sun that breathes, drawn to be watched in a dark room without glare
• A tone that swells and eases on the same clock as the sun — never out of step
• A soft tap at the turn of each breath, so you can practise with your eyes closed
• Your own pace, from 4.5 to 7 breaths per minute — the ideal one is personal
• Sessions of 3, 5, 10 or 15 minutes
• Keeps playing with the screen off
• A quiet record of your practice, kept on your device

What it doesn't do

• No account, no sign-up
• No email address
• No subscription
• No advertising
• No analytics of any kind
• No internet — the app doesn't even ask for the permission

Your settings and your practice history never leave your phone. Details in the privacy policy.