Sleep, Actually
Sleep efficiency
The proportion of time in bed that was actually spent asleep.
Sleep efficiency compares time asleep with time spent in bed, expressed as a percentage. Eight hours in bed with six hours asleep is around 75%.
It is a description, not a grade. A low figure does not mean someone slept badly on purpose, and a high figure does not mean the night was restorative.
NAP deliberately does not score your nights. If a figure from a study or a device concerns you, that is a question for a clinician rather than something to optimise alone.
Definitions on this page
- Sleep efficiency
- Percentage of time in bed that was spent asleep.
Related journal prompts
Optional. Recording what you notice may help you prepare questions for a qualified healthcare professional. NAP never infers a cause from what you write.
- How did last night feel, in your own words, before you look at any number?
Related practical tools
Nearby
More in this part of the hub
Sleep latency
How long it takes to fall asleep after the lights go out.
REM latency
How long after falling asleep the first REM period begins.
Polysomnography — the overnight sleep study
An overnight recording of brain activity, breathing, heart rhythm, eye movement, and muscle activity while you sleep.
Multiple Sleep Latency Test (MSLT)
A daytime test of scheduled nap opportunities, measuring how quickly you fall asleep and whether REM appears.