The Multiple Sleep Latency Test (MSLT)

The Multiple Sleep Latency Test (MSLT) provides an objective measure of how quickly you fall asleep when given the opportunity.  It also allows your sleep pattern to be monitored during the transition from wake to sleep.  As your ability to fall asleep can be influenced by many factors, it is very important that you strictly adhere to the following instructions prior to, and during the study.


The Multiple Sleep Latency Test (MSLT) is performed on the day following an overnight sleep study.  Your sleep is monitored on the night before the MSLT to ensure you have had adequate sleep and to detect any sleep disorders which may disrupt your sleep, causing you to experience excessive daytime sleepiness.  Should a significant sleep disorder be detected overnight, the MSLT may be cancelled or rescheduled to another day.

The MSLT consists of a series of four to five daytime nap opportunities, separated by two-hour intervals. 

During each nap you will be instructed to simply relax and let yourself fall asleep.  Your sleep pattern will be monitored during each nap which will be conducted in a darkened room.  In the two-hour interval between naps, however, it’s very important that you remain awake, as any inadvertent sleep during this time may affect your ability to fall asleep on the subsequent monitored ‘naps’.   During these intervals you can watch TV, read or bring something to work on


Following your overnight sleep study some of the electrodes/sensors used overnight, but no longer required for the MSLT, will be removed and you will be asked to change from your night attire into your normal day clothes.  The electrodes applied to your face/head will remain attached for the MSLT.

The MSLT is commenced between 1.5 and 3 hours following the end of your overnight sleep study.  During this intervening period it is again essential that you remain awake and out of bed.

The overnight sleep study will generally be ended at 7:00am and the MSLT commenced between 9:30-10:00am


As caffeine and nicotine are stimulants we ask that you don’t have any caffeine-containing food or drinks on the day of the MSLT.  This includes coffee, tea, cocoa, chocolate, cola, and also guarana-containing drinks such as Red Bull and V.  You cannot consume alcohol on the day of the study.

You will be able to smoke (outside the hospital grounds) on the day of your study; however, we will ask that you stop smoking 30 minutes before each nap.


During the two weeks prior to your MSLT your Physician may have asked you to complete a sleep diary to provide information about your normal sleep pattern.  Please ensure you bring your completed diary to your sleep study appointment.


Breakfast and lunch will be provided.  Should you wish to bring any additional snacks please ensure that any foods or drinks you bring do not contain caffeine, alcohol or guarana.