Daytime Sleepiness

Multiple Sleep Latency Test (MSLT/MWT)
Assessment of Narcolepsy and Excessive Somnolence

The Multiple Sleep Latency Test (MSLT) is used to determine the extent of daytime sleepiness, and to test for the likelihood of narcolepsy, a debilitating sleep disorder that affects one in 100,000 people. Symptoms of narcolepsy include irresistible sleep attacks, vivid hallucinations, sleep paralysis, and muscle weakness associated with strong emotion such as laughter.

The MSLT test is performed following an overnight polysomnogram. Upon awakening, you will be asked to change into daytime clothing, have breakfast and perform morning chores, and then return to bed to try and take a nap. During this nap, some of the testing sensors from the previous night will remain on your scalp and face. The technologist will monitor your brain waves and body signals for a short period of time, and then rouse you, whether you fall asleep or not. You will then repeat this procedure four or five times throughout the day, about every two hours. In between the nap trials, you will be able to read, watch TV, work on hobbies or business, have lunch, use the bathroom, and go about your normal activities, although you will not be permitted to exercise strenuously, leave the premises or return to sleep (except during the nap trials!).

The Maintenance of Wakefulness Test (MWT) is performed to verify your ability to remain awake during permissive situations. Like the MSLT, it is conducted after completing an overnight polysomnogram. You will be asked to sit or lie comfortably in a sound and light attenuated room and remain awake and alert without any exceptional exertions for a forty minute span. Any sleep during this test is considered abnormal. The test is then halted and resumed at two hour intervals throughout the day, and you are not permitted to sleep in the interim.