Nostresso

Your Apple Watch already measures stress signals. Nostresso turns them into honest, private insight — all on your iPhone, never in the cloud.

Nostresso turns the heart data your Apple Watch already collects into an honest, personal stress score — computed entirely on your iPhone. No account. No cloud. No subscription.

REAL PHYSIOLOGY, NOT GUESSWORK Your stress score (0–100) comes from heart rate variability (SDNN) and resting heart rate, normalized against your own baselines for sleep, quiet days, and active days. Nostresso shows you how confident it is in every score instead of pretending to be certain — and it recalibrates itself to your physiology every 48 hours.

ON YOUR WRIST TOO The Nostresso Watch app gives you the calm glance: your current stress, Body Battery, recovery, and goal progress — right on your watch. Add the Current Stress and Goal Progress complications to your watch face and your day's state is always one glance away.

SEE WHAT ACTUALLY DRIVES YOUR STRESS Nostresso correlates your stress with real-life factors — sleep, movement, daylight, noise exposure, mindful minutes, caffeine, and alcohol — and surfaces personal takeaways like which factor moves your stress the most. Not generic advice: your data, your patterns.

RECOVER, DON'T JUST MEASURE Body Battery, recovery status, and sleep quality show whether you have capacity for a demanding day or need to slow down first.

A COACH THAT LIVES ON YOUR PHONE A short daily insight is generated on-device with Apple Intelligence, grounded in your actual numbers. Set stress, recovery, sleep, or mindfulness goals and get on-device recommendations that adapt to where you are — not where an average user is.

PRIVATE BY ARCHITECTURE Nostresso has no servers and makes no network connections. Your health data never leaves your iPhone — that is not a policy, it is how the app is built.

WORKS QUIETLY IN THE BACKGROUND No manual measurements needed. Nostresso processes new Apple Watch readings as they arrive, and can notify you when stress stays elevated — so you can breathe, take a walk, or just close the laptop.

REQUIRES • iPhone with iOS 26 or later • Apple Watch (worn day and night for best calibration) • On-device AI insights require iPhone 15 Pro or newer; a rule-based fallback is included

Nostresso is not a medical device and does not diagnose, treat, or prevent any condition.