Sleep, Actually
Polysomnography — the overnight sleep study
An overnight recording of brain activity, breathing, heart rhythm, eye movement, and muscle activity while you sleep.
NHLBI describes polysomnography as a sleep study that records brain activity, eye movement, heart rate, breathing, oxygen levels, and muscle activity while you sleep, usually overnight in a sleep centre.
Sensors are attached to the scalp, face, chest, and legs. They record; they do not send anything into you, and the study is not painful.
For daytime-sleepiness questions, an overnight study is commonly performed the night before a Multiple Sleep Latency Test, so the daytime results can be read in context.
Definitions on this page
- Polysomnography (PSG)
- An overnight, multi-sensor recording of sleep in a sleep centre.
What does that mean?
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.
Sleep efficiency
The proportion of time in bed that was actually spent asleep.
Multiple Sleep Latency Test (MSLT)
A daytime test of scheduled nap opportunities, measuring how quickly you fall asleep and whether REM appears.