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This information was reviewed and approved by Sheila Tsai, MD (12/1/2012).

Based on your history and physical examination, your doctor may recommend a sleep study. For such a study, you usually stay overnight in a sleep laboratory, a specialized unit with computerized monitoring equipment that is staffed by sleep technolgists. The sleep study can help your doctor make a diagnosis and guide treatment by providing information on everything from body position and blood oxygen levels to heart rate, breathing and eye movements.

During a typical sleep study, you will be connected to electrodes that will record your brain waves and muscle movements throughout the night. A microphone will record snoring, and two belt-like straps around the chest and lower abdomen will monitor muscle movement during breathing.

Other tests your doctor may recommend include:

Multiple Sleep Latency Test (MSLT)

This is a test to objectively determine your degree of daytime sleepiness. This test is also done in a sleep laboratory. On the day following your overnight sleep study, you will be asked to take 4 or 5 naps over 8 to10 hours. Each nap period lasts about 20 minutes. During these naps you will be closely monitored, as you were during your sleep study.

Maintenance of Wakefulness Test (MWT)

This test measures your ability to stay awake. It consists of 4 nap opportunities. Each lasts 40 minutes. During these periods you will be asked to try to stay awake. Most people without excessive sleepiness are able to remain awake.


An actigraph is a device worn over the wrist like a watch. This device records a signal when movement is detected.  Some actigraphs can also record light around the watch. It records a signal when movement is detected. There are no signals recorded during sleep or inactivity. Signals are recorded with motion or activity. This can provide information about periods of rest/sleep or activity. The device is worn for several days to weeks, if needed.

Lab Tests

Your doctor may order laboratory tests, including those to test for medicines known to affect one's level of alertness, such as stimulants, opiates, and anti-anxiety medicines.

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