Plain answers about the strap you already wear.
What a stress score measures, what it can't see, and how to read the signal your Whoop broadcasts all day. Written plainly, sourced at the foot.
- What does the Whoop stress score actually measure?
Cardiac arousal: heart rate rising while heart-rate variability falls. It is a real physiological signal, read continuously — and it is content-blind. It registers that your body responded to something; it cannot see what the something was.
- What does Whoop sync to Apple Health?
Workouts, sleep, and once-daily summary values — resting heart rate, respiratory rate, blood oxygen. What it does not sync: continuous heart rate (Apple Health receives one heart-rate value per day) and HRV, which is excluded entirely.
- Why does my Whoop say I'm stressed when I feel fine?
Because the score doesn't measure how you feel. It measures autonomic arousal — heart rate up, heart-rate variability down — and for anyone whose days are demanding by choice, that signal sits high all day whether the day was miserable or the best one all month.