The Multiple Sleep Latency Test (MSLT) is a sleep disorder diagnostic tool. It is used to measure the time it takes from the start of a daytime nap period to the first signs of sleep, called sleep latency. The test is based on the idea that the sleepier people are, the faster they will fall asleep.
It can be used to test for narcolepsy, to distinguish between physical tiredness and true excessive daytime sleepiness, or to see if breathing disorder treatments are working. Its main purpose is to serve as an objective measure of sleepiness.
The test consists of four or five, twenty minute nap opportunities that are scheduled about two hours apart. The test is often done following an overnight sleep study. During the test, things such as the patient's brain waves, EEG, muscle activity and eye movements are monitored and recorded. The entire test normally takes about 7 hours.
The MSLT may also be used extensively to test sleepiness in a number of research protocols.
The Multiple Sleep Latency Test was created in 1977 by sleep pioneers William C. Dement and Mary Carskadon. It developed out of repeating a project done in 1970 by Dr. Dement called the 90-minute day. They informally called the 0-5 minute range the twilight zone due to its indication of extreme physical and mental impairment.
Preparation: On the day of the test the patient is asked to not take any stimulants such as tea, coffee, colas and chocolate.
A clinical neurophysiologist, neurologist or sleep specialist will review the results and inform the patient or the patient's primary care physician of the interpretation of the test result in the context of the clinical problem.
Mary Carskadon's page on the MSLT