What is an MSLT (Multiple Sleep Latency Test)?

An MSLT is short for Multiple Sleep Latency Test –  This is a test commonly ordered when the physician suspects the patient’s excessive daytime sleepiness may be related to hypersomnia or, in rarer cases, narcolepsy.  In a nutshell, this test is a way to objectively define individual tiredness.


The MSLT is conducted during the daytime at the sleep center.  Before the MSLT can be conducted during the day, the patient must sleep overnight at the sleep center the night before the MSLT is scheduled.  This is done to ensure that the patient received an adequate amount of sleep prior to the daytime MSLT and to rule out any variables which may contradict the results of said MSLT.


The MSLT itself is quite simple.  The test consists of four to five short naps spaced at two hour intervals throughout the day.  The first nap generally begins at 8:00am with the next being at 10am, 12pm, 2pm and 4pm.  During each the patient is allotted 20 minutes to fall asleep and 15 minutes to sleep.  This means the shortest nap could be 15 minutes and the longest nap could be 35 minutes.  Between naps there is roughly 1 hour and 30 minutes of downtime.  During this time patients are free to do as they please.  You can watch TV, talk on the phone, go for a walk outside, eat your breakfast/lunch, etc…


Once the final nap is over, the technologist will remove any remaining sensors and cables, and the patient is able to leave.  The data will be collected, scored, and then interpreted by the physician.  Our office will follow up with a call to schedule an appointment to discuss the results with a physician.

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