The multiple sleep latency test (MSLT) tests for excessive daytime
sleepiness by measuring how quickly you fall asleep in a quiet environment
during the day. Also known as a daytime nap study, the MSLT is the standard
tool used to diagnose narcolepsy and idiopathic hypersomnia.
The MSLT is a full-day test that consists of five scheduled naps separated by
two-hour breaks. During each nap trial, you will lie quietly in bed and try to
go to sleep. Once the lights go off, the test will measure how long it takes
for you to fall asleep. You will be awakened after sleeping 15 minutes. If you
do not fall asleep within 20 minutes, the nap trial will end.
Each nap will be taken in a dark and quiet sleep environment that is
intended for your comfort and to isolate any external factors that may affect
your ability to fall asleep. A series of sensors will measure whether you are
asleep. The sensors also determine your sleep stage.
The MSLT will be preceded by an overnight sleep study in the facility. This is to
ensure that the previous nights sleep was adequate and not disrupted by another
sleeping disorder or other external factors. The test will be looking for excessive
daytime sleepiness. Excessive daytime sleepiness occurs when you are sleepy
when you should be awake and alert.
Our board-certified sleep medicine physicians will recommend an MSLT if they
suspects you have excessive daytime sleepiness related to narcolepsy or a hypersomnia.