Multiple Sleep Latency Test (MSLT)

In the multiple sleep latency test (MSLT), a person is given 4-5 opportunities to sleep every two hours during normal wake times. The specialist uses the test to measure the extent of daytime sleepiness (how fast the patient falls asleep in each nap, also called sleep latency), and also how quickly REM sleep begins. A positive MSLT is obtained when the patient falls asleep with a mean sleep latency below 8 minutes in the naps, and had at least no more than 1 nap (for idiopathic hypersomnia) or 2 naps (for narcolepsy diagnosis) where REM sleep was reached.