Multiple Sleep Latency Tests for Measuring Daytime Sleep Disorders

Jun 11, 2025

Multiple sleep latency tests (MSLT) measure the time it takes you to fall asleep within a quiet environment during the day. As defined by the American Academy of Sleep Medicine, the standard MSLT lasts the better part of a day and incorporates five scheduled naps. It’s typically performed as a follow-up to an overnight sleep study that monitors the duration and quality of nighttime sleep.

Each of the five nap trials occurs two hours after the previous one starts. The patient lies quietly in bed with lights off, in a socially isolated environment, and attempts to sleep. A technologist places digitally connected sensors comfortably on the face, head, and chin. These sensors not only measure how fast sleep occurs but also how soon rapid eye movement (REM) sleep is reached. Making up around one-fourth of total sleep time, REM is the sleep stage at which dreams occur and where brain activity levels are much the same as when awake.