Multiple sleep latency test

Multiple Sleep Latency Test
Intervention
ICD-9-CM	89.18
OPS-301 code	1-795
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The Multiple Sleep Latency Test (MSLT) is a sleep disorder diagnostic tool. It is used to measure the time elapsed 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.

The MSLT is used extensively to test for narcolepsy, to distinguish between physical tiredness and true excessive daytime sleepiness, or to assess whether treatments for breathing disorders are working. Its main purpose is to discover how readily a person will fall asleep in a conducive setting, how consistent or variable this is, and the way they fall asleep in terms of REM sleep and other brain patterns. This can be used to identify and differentiate between various sleep problems.

The test consists of four or five 20-minute nap opportunities set two hours apart, often following an overnight sleep study. During the test, data 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 during the course of a day.

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 not to consume 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.

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