Definitions for "MSLT"
abbr. multiple sleep latency test
Multiple sleep latency test. A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of excessive daytime sleepiness. Subjects are allowed a fixed number of opportunities to fall asleep during their customary awake period. Long latencies are helpful in distinguishing physical tiredness or fatigue from true sleepiness.
Multiple Sleep Latency Test. The MSLT is the primary test for the diagnosis of narcolepsy. This test assesses two major components of narcolepsy: hypersomnolence and sleep onset REM periods (SOREMPs), which occur in narcolepsy but are otherwise uncommon. The mean sleep latency, or time to sleep onset, provides evidence for hypersomnolence. Using an EEG to record sleep onset during normal waking hours, it consists of four or five 20-minute nap opportunities at two-hour intervals. Normally, sleep latency is greater than 10 minutes and REM sleep does not occur. Patients with narcolepsy typically fall asleep in 5 minutes or less and will display SOREMPs during at least two of the five daytime nap periods.