Sleep Efficiency Calculator (Time Asleep ÷ Time in Bed)
Sleep efficiency as a percentage, and total sleep time, from your time in bed, how long you took to fall asleep and how long you were awake.
Results
What this tool does
Sleep efficiency is the share of the time you spend in bed that you are actually asleep. Sleep clinics use 85 % as a common benchmark, and a US National Sleep Foundation consensus panel in 2017 judged 85 % or more appropriate for adults, with 75–84 % uncertain and below 75 % not appropriate. A low value usually comes from lying awake too long: staying in bed for hours you cannot sleep tends to lower efficiency, which is why cognitive behavioural therapy for insomnia works by matching time in bed to time asleep. Wearables only estimate these minutes, so diaries and devices can disagree by a good margin.
Formula
sleep efficiency = total sleep time ÷ time in bed × 100 · sleep time = time in bed − latency − awake in the night − awake before rising
Variables
| Symbol | Meaning | Unit |
|---|---|---|
tb | Time in bed (lights out to getting up) | min |
sl | Minutes to fall asleep | min |
wa | Minutes awake during the night | min |
em | Minutes awake before getting up | min |
SE | Sleep efficiency | % |
TS | Total sleep time | min |
TH | Total sleep time in hours | h |
CL | Compared with the usual benchmark | — |
Worked example
- Time in bed (lights out to getting up)480 min
- Minutes to fall asleep15 min
- Minutes awake during the night25 min
- Minutes awake before getting up0 min
- Sleep efficiency91.7 %
- Total sleep time440 min
- Total sleep time in hours7.33 h
- Compared with the usual benchmark85 % or more — generally considered good
Limitations
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.