What Is Sleep Efficiency?

Two people can both spend eight hours in bed and have very different nights. One may sleep for seven hours and 45 minutes; the other may spend 90 minutes tossing and turning. Sleep efficiency describes that difference.

The formula

Sleep efficiency = (time asleep ÷ time in bed) × 100

If you're in bed for 8 hours and asleep for 7, your sleep efficiency is 87.5%.

What counts as good

These bands are common conventions in sleep research and sleep tracking:

• 90%+ - Excellent
• 85-89% - Good
• 75-84% - Fair
• Below 75% - Poor

One rough night is less useful than the pattern over time.

Why efficiency matters alongside duration

The duration is how long you slept. Efficiency is how settled that time was. A night with eight hours in bed and 80% efficiency (6.4 hours asleep, 1.6 hours awake) can feel worse than seven hours in bed at 95% efficiency (6.65 hours asleep), even though the second has less total sleep.

Common causes of lower sleep efficiency

• Going to bed before you're actually sleepy - lying awake waiting to fall asleep counts against you
• Screen use or stimulating activity right before bed
• Caffeine too close to bedtime
• An inconsistent schedule - see why sleep consistency matters
• A bedroom environment that's too warm, too bright, or too noisy

A simple way to improve it

One well-supported approach is to go to bed when you feel sleepy, rather than at a fixed time regardless of how you feel. If you are not asleep within about 20 minutes, get up and do something calm in low light until you feel sleepy, then try again. Over time, this can reduce the time you spend awake in bed.

Tracking it automatically

Sleep continuity, including efficiency, is a leading input to SleepKit’s quality ring, calculated from Apple Health data each night.