Adult Sleep Electroencephalogram (EEG)

Patient Experience

  • Reference Number: HEY-791/2024
  • Departments: Neurophysiology
  • Last Updated: 1 January 2024


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.

What is a sleep EEG?

A sleep EEG will be performed by a clinical physiologist. EEG is the abbreviation of electroencephalogram, which is the recording of electrical activity produced by the brain. It can help to explain fits or seizures and is a tool to 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. We ask you to deprive yourself of sleep and you may be given a small dose of melatonin which is a medication designed to help you sleep. We also record for a longer period of time than a routine EEG.

Why do I need a sleep EEG?

  • A Sleep EEG is commonly performed if you have had a routine EEG and your doctor requires further information. Occasionally, particularly if your seizures/episodes only occur in sleep, this may be the first EEG recording you have.
  • We may also perform a sleep EEG if you have any conditions that may make it difficult for you to undertake/co-operate for a routine EEG.

Can there be any complications or risks?

  • Sleep deprivation is said to slightly increase the risk of you having one of your seizures (there are no definitive figures for this risk due to different methods of performing the test, however the risk is small). This may happen to anyone, even if they do not suffer from epilepsy.
  • In some people there is a very small chance that the deep breathing or flashing lights could result in a seizure. You will be asked to sign a written consent if you are happy to include the deep breathing and flashing lights as part of the test.
  • Very occasionally you 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 attending staff.

How do I prepare for the sleep EEG?

Please read this information leaflet. Share the information with your 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.

  • Please let us know before your appointment if you are pregnant or breast feeding.
  • If you suffer from any allergies please let us know as soon as possible.
  • You will not be able to drive after your test due to the medication you have been given and it is advisable for you to have someone to accompany you home.
  • The night before the test please try to deprive yourself of sleep by reducing your sleep by at least half (for example your normal regular sleep is 10 hours reduce it to 5 hours).
  • For 24 hours prior to the test please avoid drinking tea, coffee or any beverages containing caffeine (for example energy drinks and some fizzy drinks).
  • Please wash your hair before you come to the hospital and do not use any hair products (gel, hairspray etc).
  • Take your medication as normal unless otherwise directed by your doctor.
  • Please have a light meal prior to your attendance.
  • Please bring a list of any current medication you are taking.

What will happen?

  • On your arrival in the department, we will obtain your consent for the procedure before your investigation begins.
  • The clinical physiologist performing the Sleep EEG 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 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. We will generally ask them to leave before we start the recording. If this is going to be a problem for you, please discuss this with the clinical physiologist.
  • You will be given your dose of melatonin (if appropriate).
  • 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.
  • You will be asked some questions about the condition leading to your referral for a Sleep EEG.
  • While you are sat on the chair or after laying on the bed comfortably, the electrodes will be placed on your head using sticky paste.
  • The recording will take approximately an hour and during this time we will ask you to open and close your eyes at different times.
  • During the test you will be asked to breathe deeply for a short time and then afterwards you will be asked to try to fall asleep.
  • The room will then be darkened to encourage sleep.
  • For part of the test you may be asked to watch a flashing light although this may be unnecessary if you have recently had a routine EEG.

Use of Melatonin in sleep EEG

  • You may be given a dose of melatonin prior to recording your sleep EEG.
  • Whilst melatonin is licensed in the UK, in some circumstances in its prolonged released form, it is not currently licensed in its immediate release form.
  • The immediate release form is widely and frequently used nationally and is recognised as a safe medication for the promotion of sleep during EEG recordings.
  • Further information regarding melatonin can be found in the NICE (National Institute for Health and Care Excellence) guidelines (Epilepsies diagnosis and management- investigations 1.6.15) and information on unlicensed medications at (medicines information licensing).
  • If you have any concerns please contact the department and ask to speak to a physiologist or ask the physiologist performing the EEG recording on the day.

What happens afterwards?

  • The electrodes will be removed and your head cleaned with warm water. You may wish to bring a brush or comb with you to tidy your hair. Any residue of paste can be removed by shampooing the hair at home.
  • You may still feel drowsy following the test due to a combination of lack of sleep and the effects of Melatonin. We recommend that you have someone to accompany you home after the test.
  • Under no circumstances should you drive until the following day.
  • Once you have left the department the recording will be reviewed by the physiologist and then by a member of the medical team or senior physiologist who will send a report to the doctor who referred you for the sleep EEG. 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 01482675339 or 01482675388.

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.

QR code to open leaflet