What WHOOP measures

WHOOP tracks all four stages of sleep — slow wave sleep (SWS), REM, light, and awake — with near-perfect accuracy. Each stage serves a different purpose in your recovery.

WHOOP calculates how much sleep you really need based on recent sleep patterns, the strain from the day, sleep debt you’ve accrued, and any recent naps you’ve taken.

Quality of sleep is just as important as quantity. WHOOP monitors your wake events, efficiency, and respiratory rate to deliver daily recommendations on how to get your best sleep every night.

WHOOP helps you schedule your bed and wake times based on how strenuous your day was, when you need to wake up, and how you’re looking to perform the next day. You can also set custom haptic alarms that will wake you when you’re fully rested, or at a specific time.

See your sleep performance over the week, month, or year to identify patterns and build a better bedtime routine.

WHOOP calculates your recovery on a scale of 0 to 100% during your sleep, looking at your heart rate variability (HRV), resting heart rate, respiratory rate, SpO2, sleep performance, and skin temperature to see how your body is adapting to physiological and psychological stress. The biggest influence is by far your HRV but it also considers your health, behaviors, stress levels, hydration, and more.

See how your body adapts to strain, stress, illness, sleep and more with three simple color-coded ranges. If you’re in the green, and you’re ready to take on more, yellow means you can maintain, and red signals you need more time to rest.

See your weekly, monthly, or 6-month recovery trends to fine tune your strategies to get the most out of the way you rest and recover.

Stress Monitor measures your heart rate and HRV in the moment as an indicator of your physiological response to stress. That reading is compared to your 14-day baseline to calculate a Stress Score between 0 and 3, taking into account any motion to distinguish known stressors, like exercise, from other stressors.

Stress Monitor will recommend science-backed breathwork exercises developed to either increase relaxation or alertness depending on your stress level.

Aside from measuring stress in real time, Stress Monitor also allows you to look at stress a day, a week, a month, or six months at a time to spot patterns in your stress levels.