Sleep studies are tests that record what happens to your body during sleep. The studies are done to find out what is causing your sleep problems.
Sleep studies can also determine whether you have a problem with your stages of sleep. The two main types of sleep are non–rapid eye movement (NREM) and rapid eye movement (REM). Normally, NREM and REM alternate 4 to 5 times during a night’s sleep. A change in this cycle may make it hard for you to sleep soundly.
Common sleep studies
The most common sleep studies are:
- Polysomnogram. This test records several body functions during sleep, including brain activity, eye movement, oxygen and carbon dioxide blood levels, heart rate and rhythm, breathing rate and rhythm, the flow of air through your mouth and nose, snoring, body muscle movements, and chest and belly movement.
- Multiple sleep latency test (MSLT). This test measures how long it takes you to fall asleep. It also determines whether you enter REM sleep.
- Maintenance of wakefulness test (MWT). This test measures whether you can stay awake during a time when you are normally awake.
If your doctor thinks that you may have shift work sleep disorder or another problem with your body’s internal clock (circadian rhythm), you may have a test called actigraphy. For this test, you wear a device on your wrist that looks like a watch. The device measures your movement during sleep and when you are awake. It helps your doctor learn what times during the day you are active and what times you are sleeping.
Sleep studies usually are done in a sleep lab. But sleep studies also can be done with portable equipment you use at home.