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Multiple sleep latency test (MSLT)

What is a multiple sleep latency test?

A multiple sleep latency test (MSLT) is a non-invasive daytime sleep study to measure your child’s daytime sleepiness.

During this study your child is given 4 or 5 opportunities to sleep at designated times in a quiet darkened room. The test measures the average time it takes your child to fall asleep. This test takes place straight after an overnight full polysomnography sleep study.

What happens in the morning?

In the morning after your full polysomnography sleep study, staff will wake your child up no later than 7am and remove the following sensors:

  • 2 sensors on the upper lip
  • CO2 monitor on the chest
  • snore sensor
  • bands around the torso
  • body position sensor
  • 4 stickers on the legs
  • soft probe on the toe

You and your child will then be able to get up and dressed ready for the day. We recommend bringing comfortable clothing for your child during the day as they will be attempting to have naps.

Photograph of child with sensors stuck on their face

What does the daytime testing involve?

The MSLT involves 4 or 5 daytime naps.

For each nap your child will be asked to get into bed and lie still, close their eyes and try to go to sleep. They will be left for around 30 minutes, during that time we will be monitoring how long it takes them to fall asleep (if at all) and what type of sleep they have.

The test is repeated across the day at set time intervals (9am, 11am, 1pm, 3pm and 5pm).

For younger children we can set up a parent bed for you to also ‘nap’ during each of the daytime nap opportunities. During each nap, sleep patterns and video (with written consent) will be recorded.

Photograph of child sleeping during MSLT nap

What else happens during the day?

You are responsible for your child throughout the day and we ask that you do not let your child nap between tests or consume food containing caffeine (tea, coffee, chocolate etc) as these both will affect their levels of alertness.

There is free time in between the daytime naps and the head sensors can be tied into a ponytail so they don’t interfere with activities. You and your child will be provided with breakfast and lunch at the Sleep House. Due to the timings of the sleep test there is not an opportunity to buy hot food during the day.

We recommend that you spend some time out of the bedroom during between sleep tests. Some children feel self-conscious about the sensors on their head and face so we advise bringing a hat or hoodie to wear.

What happens afterwards?

After the last daytime nap, a staff member will remove the sensors. We will then discharge your child and you will both be free to go home.

Quite often we can get the results we need after 4 of the 5 naps, and so you may be free to leave at 3.45pm (if 4 naps are needed) or 5.45pm (if 5 naps are needed). We will be able to let you know what time the daytime tests will end on the afternoon of your child’s testing. 

How long does it last?

The overnight sleep study will last one night and the MSLT lasts the whole of the next day.

When will I get the results?

The sleep physiology staff will pass the data onto the sleep and respiratory team. The sleep and respiratory consultant will then look at the results and they will be discussed either at your next clinic appointment or the results will be sent to the referring doctor.


Results will not be available during your stay with us. It can take a few weeks to get the results.

Contact us

If you have any questions or concerns you can speak to the sleep physiology team on 0114 305 3042. Please leave a message on our answer phone and we will get back to you as soon as possible.

If you are unable to come in for this appointment, please contact the bookings team on 0114 226 0698 to rearrange a new date. We would really appreciate you letting us know as soon as possible if you are unable to attend, so we can offer the slot to another patient on our waiting list.

The Sleep House, 20 Claremont Crescent, Sheffield, S10 2TA

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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: SLP5

Resource Type: Article

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