Everything Cortisol+ does
Real-time cortisol estimation, sleep-cortisol correlation, and guided breathwork — all powered by your existing Apple Watch.
Most wearables show you a generic "stress" number and stop there. Cortisol+ is built around a single question: what is your cortisol pattern doing, and what actually moves it? The three features below work as a loop — the HRV score shows you where you are right now, sleep analysis explains why your morning started high or low, and Zen mode gives you a way to intervene and verify the intervention worked. Everything runs off sensors already on your wrist; there's no extra hardware, and the estimate is a biometric pattern indicator, not a lab measurement.
HRV-based cortisol score
Continuous estimation from heart rate variability — the gold standard wearable biomarker for autonomic stress. Personalized to your baseline.
Sleep × cortisol
See how every night of sleep drives next-morning cortisol. REM, deep, and core sleep stage analysis correlated with your HRV-derived cortisol pattern.
Zen mode & breathwork
Guided breathing protocols — box, 4-7-8, physiological sigh, resonance — with Apple Watch HRV measurement of the cortisol-lowering effect after every session.
The three features, in depth
1. Real-time cortisol score from HRV
Heart rate variability is the best-validated wearable signal of autonomic stress: when your sympathetic nervous system ramps up, HRV drops. Cortisol+ reads the SDNN measurements your Apple Watch takes throughout the day, weighs them against your resting heart rate and personal baseline, and translates the result into a cortisol-pattern score you can check at a glance. Because the baseline is yours — not a population average — the score gets more accurate the longer you wear the Watch. Pattern alerts flag unusual elevation before you consciously feel it.
Explore HRV stress monitoring →
2. Sleep × cortisol correlation
Sleep and cortisol regulate each other: short or fragmented sleep pushes next-day cortisol up, and elevated evening cortisol fragments sleep in return. Cortisol+ pulls your REM, deep, and core sleep stages from Apple Health and lines each night up against the following morning's stress estimate, so you can see which specific nights — the late screens, the nightcap, the 5-hour crunch — drove a rough morning. Over weeks, the correlation view shows which sleep habit is your highest-leverage fix.
Explore sleep × cortisol tracking →
3. Zen mode guided breathwork
Slow, paced breathing is one of the few stress interventions you can deploy in the moment — it stimulates the vagus nerve and shifts the nervous system toward its parasympathetic "rest" state. Zen mode guides you through box breathing, 4-7-8, physiological sighs, and resonance breathing, then uses an Apple Watch HRV reading to show whether the session actually moved your physiology. Instead of taking it on faith that breathwork "works," you see your own before-and-after.