Sleep Study Test
A sleep study (polysomnography) measures your breathing, oxygen levels, heart rate, brain waves, and movements during sleep to diagnose sleep disorders like sleep apnea, insomnia, restless leg syndrome, and narcolepsy.
What this test measures
A sleep study measures and records body functions while you sleep, including breathing rate, blood oxygen level, heart rate, brain waves, leg movements, and eye movements.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Frequently asked questions
What is a sleep study?
A sleep study, also called polysomnography, is a test that measures and records body functions while you sleep, including breathing, oxygen levels, heart rate, brain waves, and movements.
Why might I need a sleep study?
A sleep study is used to diagnose sleep disorders such as sleep apnea, insomnia, restless leg syndrome, and narcolepsy.
What does the Apnea Hypopnea Index (AHI) mean?
The AHI counts how many episodes of sleep apnea you have per night. More than five episodes probably means you have sleep apnea.
What is sleep efficiency?
Sleep efficiency is the total minutes you sleep compared to the time you spend in bed. Low sleep efficiency means you spend a long time in bed without sleeping.
What is a normal oxygen level during sleep?
A normal oxygen level during sleep is 90% or higher. Levels below 90% are considered abnormal.
Related lab tests
Sources
- MedlinePlus: Sleep Study — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.