Calculator
Sleep Efficiency Calculator
Sleep efficiency is the percentage of time in bed you actually spend asleep. Above 85% is healthy. Below 80% is the diagnostic threshold where CBT-I — specifically sleep restriction therapy — has the strongest evidence of benefit.
Lights-out to final wake.
Subtract time awake in bed and middle-of-night waking.
Sleep efficiency
81%
Borderline. Below 85% suggests sleep onset latency or middle-of-night waking. Worth investigating sleep hygiene and stimulus control.
- <80%: CBT-I indicated
- 80–85%: borderline
- 85–90%: healthy
- >90%: excellent
How it works
The formula is simple: sleep efficiency = (time asleep ÷ time in bed) × 100. Time in bed runs from lights-out to your final wake-up; time asleep subtracts any time you spent awake in bed (including middle-of-night waking).
This is one of the core metrics in CBT-I (Spielman, Saskin & Thorpy, 1987). The intervention sleep restriction therapyworks by deliberately reducing time in bed to push efficiency above 85% — then gradually expanding time in bed once it's consolidated. Counterintuitive, but very well evidenced.
Why it matters
Sleep efficiency is more diagnostic than total sleep time. Someone sleeping 6 hours out of 6 in bed is doing well; someone sleeping 6 hours out of 9 in bed has a clinically meaningful problem.
Sources
- 1Spielman, A. J., Saskin, P. & Thorpy, M. J.. Treatment of chronic insomnia by restriction of time in bed · Sleep · 1987PMID 3563247