Multiple Sleep Latency Testing (MSLT)

Patient Leaflets Team

  • Reference Number: HEY-778/2019
  • Departments: Neurophysiology
  • Last Updated: 31 May 2019


This leaflet has been produced to give you general information about your procedure.  Most of your questions should be answered by this leaflet.  It is not intended to replace the discussion between you and the healthcare team, but may act as a starting point for discussion.  If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team caring for you.

What is a multiple sleep latency test?

An MSLT will be performed by a clinical physiologist.  It is a way of recording the electrical activity produced by the brain as well as some other parameters including eye movements, ECG and muscle while you are sleeping.  It can help to explain reasons why you may be feeling sleepy during the day, falling asleep suddenly and having difficulty keeping awake and may help your doctor in making a diagnosis.  The activity is recorded on a computer and a video recording of you is made at the same time.

Can there be any complications or risks?

Very occasionally people may experience a slight local reaction at the electrode site.  This may cause reddening and soreness.  These symptoms resolve quickly on removal of the electrodes. If you experience these symptoms, please inform the staff attending to you.

How do I prepare for an MSLT?

Please read this information leaflet.  Share the information it contains with your partner and family (if you wish) so that they can be of help and support.  There may be information they need to know, especially if they are taking care of you during / following this examination.

  • You will be sent a sleep diary to complete for the 2 weeks leading up to your MSLT appointment.  Please ensure this is filled in accurately.
  • Wash your hair before you attend and do not use any hair products (gel, hairspray etc).
  • For 2 weeks prior to attending you need to refrain from taking any sleeping tablets, sedatives, anti-histamines, anti-depressants or stimulants.  We advise, if you are on any medication, take this letter to your doctor who will let you know which of the medications you need and which to stop taking.  Do not stop any medication without your doctor’s advice.  
  • You may eat as normal on the day of your MSLT, however, please refrain from having any drinks containing caffeine.
  • Bring some lunch with you and snacks for the day. We are able to provide water and decaffeinated tea and coffee.
  • Bring a list of any current medication you are taking.
  • Bring something to keep you occupied during your stay with us for example magazines, books etc.
  • If you smoke you will be discouraged from doing so as it may affect the results. If you think this will be a problem please inform us before you attend for your MSLT.

What will happen?

  • On your arrival in the department we will obtain your consent before your investigation begins.
  • The clinical physiologist performing the MSLT will explain the test to you and will be happy to answer any questions you may have.
  • Generally we ask people to come into the examination room by themselves as experience shows this makes it easier for people to fall asleep. Sometimes we will ask the person accompanying you to come through at the start if they can supply additional information about your condition but we will ask them to leave before we start the recording.  If this is going to be a problem for you, please discuss this with the physiologist.
  • You will be asked to sit on a chair and have your head measured and some points will be marked on it with a soft pencil and several small electrodes will be placed on your head using sticky paste and some netting placed over your head to ensure the electrodes are secure for the day.
  • You will be asked some questions about the condition leading to your referral for an MSLT.
  • You will then be asked to lie on a bed and several small electrodes will be placed around your eyes, on your chin and also on your hands.
  • The test will begin with you laid on your back with the lighting dimmed in the room and you will be asked to close your eyes and try to fall asleep. You will be given 20 minutes to fall asleep.  If you fall asleep we will record for 20 minutes more, however if after 20 minutes you have not fallen asleep the first test will be ended.
  • At the end of the first test you will be asked to get off the bed with the electrodes still in situ and sit on a chair in the same room where you can keep yourself occupied until it is time for the next test. If you have a companion with you they may be in the room with you at this point.  Please try and stop yourself from falling asleep during this period.
  • 2 hours after the start time of the first MSLT you will be ready for the second MSLT to begin and you will be asked to lie on the bed and try to fall asleep again. Approximate times for the MSLT to start are 8.30am, 10.30am, 12.30pm, 2.30pm and 4.30pm.  You will be in the department from 8am until approximately 5.30pm.
  • At the end of the fifth MSLT the electrodes and paste will be removed from your hair with warm water and you are able to leave. Any residual paste can be shampooed out at home.

What happens afterwards?

Once you have left the department the recording will be reviewed by the physiologist and then by a member of the medical team who will send a report to the doctor who referred you for the MSLT.  This usually takes up to two weeks.

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the Neurophysiology Department (01482) 675339 / 675388

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

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