Sleep Education

American Academy of Sleep Medicine 

Find a Center
Use the following fields to locate sleep centers in your area.

Search radius:

Multiple Sleep Latency Test (MSLT) - Testing Process & Results

Testing Process

The MSLT will last most of the day. Over the course of the day, you will take five scheduled naps. Each of these nap trials is separated by a two-hour break. Depending on the results, a shorter four-nap study may also be used. Be prepared to stay for the full five-nap version of the study.

You will take your first scheduled nap an hour-and-a-half to three hours after you wake up from the overnight sleep study. About an hour before your first nap trial, you will eat a light breakfast.

A sleep technologist will gently place sensors on your head, face and chin. These sensors are connected to a computer. Each is long enough so you can move around and turn over in bed. The sensors show when you are asleep and awake, and transmit data used to determine when you are in REM sleep. Once you are connected, the technologist will test the sensors by asking you to move your eyes, clench your teeth and turn your head. A low-light video camera will allow the technologist to observe your MSLT from a nearby room.

The nap trial begins when the lights are turned off. You will lie quietly in bed and try to go to sleep. The MSLT will measure how long it takes you to fall asleep. It will also measure how long it takes for you to reach REM sleep.

The technologist will awaken you after you have slept for 15 minutes. If you are unable to fall asleep, the nap trial will end after 20 minutes. At this time you will have an approximately two-hour break. You will need to stay awake, and you are free to keep busy in whichever way you choose.

This process will repeat four more times. After your second (noon) trial, you will have a light lunch. After your final nap trial, you will test the sensors again and they will be removed. You are free to leave when the final trial is complete.


It will take about two weeks to get the results of your MSLT. During this time, members of the sleep team will examine the results of your MSLT.

A sleep technologist will be the first to look over the MSLT data. The technologist will chart when you fell asleep during each nap study. He or she will also look at your sleep stages and determine whether or not you entered REM sleep. Patients with narcolepsy often have two or more REM during the MSLT. People with idiopathic hypersomnia fall asleep easily but do not reach REM sleep during the nap trial.

The technologist will then hand the results over to the board-certified sleep medicine physician to interpret. The doctor will use this information to make his or her diagnosis. If the physician needs any more information about your study, he or she may speak to the technologist.

Once the doctor has determined what sleep disorder you have, he or she will contact you to discuss a treatment plan. If your primary care physician or another doctor ordered the MSLT, the board certified sleep medicine physician will send them the results.

« return to Preparing for the MSLT