How the sleep score works
Every night gets a score out of 100, modelled on the way Apple Health rates sleep. Apple's exact formula is private, so this is a close approximation, not a copy of the number in the Health app.
The score is the sum of three parts: how long you slept, when you went to bed, and how settled the night was.
Duration
Worth up to 50 points. Half the score is simply how long you slept. Hit 7 hours 50 minutes or more and you keep all 50 points. Below that, points come off increasingly steeply the shorter the night. When a night is detailed enough to show stages, unusually little deep sleep or unusually little REM each cost a further 5 points.
Bedtime
Worth up to 30 points, and it is really about consistency. Your bedtime is compared to your typical bedtime over the previous couple of weeks. Going to bed around your usual time, or earlier, keeps all 30 points. Later than usual costs roughly a point for every 5 minutes, and going to bed very early loses a few points too.
Interruptions
Worth up to 20 points, for how settled the night was. A few minutes awake is normal and free. Beyond about 11 minutes awake you lose roughly a point per 4 minutes, and frequent wake-ups chip away a little more.
Bands
- Excellent, 96 to 100
- High, 81 to 95
- OK, 61 to 80
- Low, 41 to 60
- Very low, 0 to 40
Scores are calculated once from the recorded sleep stages and stored, so they reflect what was typical for you at the time. Because the underlying thresholds are an approximation, the number will sit close to, but not exactly on, the one Apple shows.