Sleep, Actually
Sleep latency
How long it takes to fall asleep after the lights go out.
Sleep latency is simply the time between trying to fall asleep and actually falling asleep. In a sleep laboratory it is measured from recorded brain activity, not from how it felt.
Short sleep latency during the day is one of the things a Multiple Sleep Latency Test looks at, because falling asleep very quickly during scheduled daytime naps is meaningful to a clinician.
A number on its own means little. Interpreting it is clinical work, and it belongs with a specialist who has the full recording and your history.
Definitions on this page
- Sleep latency
- Time taken to fall asleep after attempting to.
What does that mean?
Related practical tools
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More in this part of the hub
REM latency
How long after falling asleep the first REM period begins.
Sleep efficiency
The proportion of time in bed that was actually spent asleep.
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.