Sleep Studies

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 problems include:

• Reference Sleep apnea Opens New Window, when an adult regularly stops breathing during sleep for 10 seconds or longer. This may be caused by blocked airflow during sleep, such as from narrowed airways. Or it may be caused by a problem with how the brain signals the breathing muscles to work.
• Problems staying awake, such as Reference narcolepsy Opens New Window.
• Problems with nighttime behaviors, such as sleepwalking, night terrors, or bed-wetting.
• Problems sleeping at night (Reference insomnia Opens New Window). This may be caused by stress, depression, hunger, physical discomfort, or other problem.
• Problems sleeping during the day because you work at night or do rotating shift work. This sleep problem is called shift work sleep disorder.
• Conditions such as Reference periodic limb movement disorder Opens New Window, which is repeated muscle twitching of the feet, arms, or legs during sleep.

Sleep studies can also determine whether you have a problem with your Reference stages of sleep. The two stages 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.

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 (Reference circadian rhythm Opens New Window), 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. Sleep labs are often located in hospitals. But sleep studies also can be done with portable equipment you use at home.

Opens New Window Sleep Apnea: Should I Have a Sleep Study? Opens New Window

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