The short answer
Apple Watch gives a sleep score from 0 to 100: up to 50 points for duration, 30 for bedtime consistency and 20 for the number and duration of awakenings. In Apple’s published allocation, HRV, heart rate and deep- or REM-sleep percentages are not separate scoring components. HRV measures variation between heartbeats in milliseconds, independently of the sleep score.
Key points
- The 100 points comprise duration 50, bedtime consistency 30 and interruptions 20
- Consistency uses sleep-onset times from the previous 13 days
- The total appears in one of five bands from Very Low to Very High
- HRV is beat-interval variation, not a component of Apple’s published sleep score
- Review the three components and how rested you feel rather than treating one night as a pass or fail
The 100 points come from three components
Apple Watch summarises the previous night’s sleep on a scale from 0 to 100. Apple publishes the following three components.
- Duration — 50 points: the estimated time asleep the previous night
- Bedtime consistency — 30 points: how closely your sleep-onset time matches your recent pattern
- Interruptions — 20 points: the number of awakenings and time awake during the night
Five rating bands, not a medical assessment
The total comes with a rating label. The Apple Watch User Guide lists these five bands.
- Very Low: 0–40
- Low: 41–60
- OK: 61–80
- High: 81–95
- Very High: 96–100
Sleep score and HRV use different scales
The sleep score combines duration, bedtime consistency and interruptions into a total out of 100.
HRV describes variation in the intervals between heartbeats. Apple Health stores SDNN in milliseconds.
A score of 84 and HRV of 42 ms cannot be compared on one scale. HRV changes with measurement time, posture, breathing, exercise, alcohol and health as well as sleep.
- Sleep score: measured in points; summarises a night using three components
- HRV: measured in milliseconds; describes beat-interval variation
- Sleep score: found in Sleep on the watch or the Sleep section of Health
- HRV: found in Health → Heart → Heart Rate Variability
Deep and REM sleep are not separate scoring components
Apple Watch estimates Awake, REM, Core and Deep sleep stages.
In Apple’s published point allocation, minutes of deep sleep and the percentage of REM sleep are not independent scoring components.
Estimated wakefulness relates to interruptions, but increasing the deep-sleep percentage alone is not how the score works. Sleep stages naturally vary from night to night, and Apple Watch estimates them from sensors rather than directly measuring brain waves.
Review the three components, not only the morning total
Open Sleep
After waking, open Sleep on Apple Watch and check the total and its rating band.
Look at the three components
Open the information button and review whether duration, bedtime consistency or interruptions show room for improvement.
Review a longer period on iPhone
In Health → Browse/Search → Sleep, switch between daily, weekly and monthly views.
Check your own experience too
Record whether you feel rested on waking or very sleepy during the day. A high score is not a reason to push through feeling unwell.
If the sleep score is missing
Sleep score was introduced with watchOS 26. It requires a compatible Apple Watch and supported iPhone running iOS 26. Check Apple’s current information for eligible models.
The score appears after sleep analysis finishes, usually about 15 minutes after waking.
If it is missing immediately after waking, wait a little. If it still does not appear, check sleep-tracking settings, wear time, charge and operating-system compatibility.
References
- View your sleep score on Apple Watch — Apple Watch User Guide
- Track your sleep with Apple Watch and use Sleep on iPhone — Apple Support
- HealthKit heart rate variability (SDNN) specification — Apple Developer
More in the Feelmo guide
Reading sleep data in detailA closer look at HRVTips for consistent Apple Watch measurements