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What is a sleep deprived EEG?

What is an EEG?

EEG stands for ‘electroencephalograph’

  • Electro – the electrical impulses that are being measured.
  • Encephalo – the head.
  • Graph – the way the results of the test are presented.

An EEG is a test done in specialist hospitals. The test records the electrical activity that your brain makes whilst sending messages to and from the body. EEGs are done on babies and children of all ages and abilities.

How does an EEG work?

We produce brain waves all the time and an EEG records these brain waves. If a child has a condition that affects the pattern of these brain waves, an EEG may pick this up.

How will having a sleep deprived EEG help your child?

This depends on the problem they are having such as blackouts or seizures. It may help us find the cause of their problem so the doctor can decide the best treatment for them.

Your child may have had a standard waking EEG. A further EEG after sleep deprivation may help in two ways.

  1. Tiredness may result in us seeing brain waves on the EEG which we may not have seen before.
  2. They may fall asleep during the EEG and this can show new information not seen during the waking EEG.

How long will we be at the hospital?

You will be at the hospital for about 2 hours.

Where will the test be done?

The test is performed in a recording room on E Floor, Grey stairs or lifts, at Sheffield Children’s Hospital, S10 2TH.

The recording room contains a couch, TV with DVD player and EEG equipment. There will be a physiologist present and there is also room for parents or carers. As we are a teaching hospital, with your consent, a trainee physiologist may perform the test under direct or distance supervision or occasionally other healthcare professionals may ask to observe.

Our physiologist are used to dealing with frightened and anxious patients as well as those with sensory issues or special needs.

Parents and carers should note, there is no provision for other children to be supervised whilst your child is having their EEG. If you have any problems arranging childcare, please ring the department to discuss this.

How do we get to the EEG recording room?

The recording room is on E Floor, Grey stairor lifts, at Sheffield Children’s Hospital, S10 2TH.

The nearest entrance to the department is on Damer Street around the corner from the Emergency Department.

Then follow the signs to Grey lifts or stairs and travel to E floor and report to reception. You can also follow the signs for Grey lifts from the Main Entrance.

A map of Sheffield Children's Hospital highlighting the entrance on Damer Street

Public transport is the best way to travel to Sheffield Children’s Hospital. We are well served by bus services (51, 52, 273, 274, 275) and close to the tram route. Find out more on our public transport webpage: www.sheffieldchildrens.nhs.uk/patients-and-parents/public-transport

Please allow plenty of time for delays and roadworks. For up-to-date parking information visit our webpage on parking:

Is there anything we need to do before having the test?

Yes, you should:

  • Make sure your child goes to bed at least 2 hours later than normal and is woken at least 2 hours earlier than normal the following morning.
  • Make sure your child has a good breakfast.
  • Make sure your child has clean hair that is free from hair-spray or gel.
  • Make sure your child wears comfortable clothing that they are happy to sleep in, for instance a tracksuit or something similar so we have easy access to their arms and legs.
  • Continue with any medications they normally take. It is helpful to bring a list of their current medications with you.
  • If you would usually drive your child to the appointment and you are sleep deprived after getting up early with your child, please make alternative arrangements. It is not advisable to drive if you are sleep deprived.
    • Make sure they do not fall to sleep on the way to the appointment, this may mean having someone accompany you to keep them awake on the journey.
  • It helps if they are accompanied by a witness who can recognise and confirm their typical attacks if one were to happen during the recording.

What happens before the test?

There will be a physiologist present and there is room for parents or carers.

We see children of all ages and abilities and our physiologists are used to dealing with frightened and anxious patients as well as those with sensory issues or special needs.

As we are a teaching hospital, with your consent, a trainee physiologist may perform the test under direct or distanced supervision and occasionally other healthcare professionals may ask to observe.

Please bring drinks, snacks, a dummy and favourite toys or DVDs if you think they will help to distract your child during the preparation.

To prepare them for the test, their head may be measured. We then rub the head with a cotton bud dipped in a gritty paste. The paste holds the 23 small discs on their head to pick up their brain waves.

Two stickers on their arms or shoulders record their heart rate (ECG). Several additional stickers will be used to pick up muscle movements. This part takes about 20 minutes. During this time, you can ask any questions that you have.

Illustration of child having sticky paste put onto their forehead to connect to wires Illustration of child having their head measured

What happens during the test?

The test takes up to 1 hour.

During the test we want children to be as comfortable as possible. Older children find that they prefer to lie down. Younger children are more comfortable sitting on a parent’s knee and watching TV.

First we connect the discs to the computer. During the test, the technician will ask them to do various simple actions like:

Opening and closing their eyes, hyperventilation and photic stimulation.

Illustration of child laid down with wires connected to their head


This involves taking deep breaths in and out, like blowing a candle out. In the case of young children we do this using a party blower or a windmill.

They may feel dizzy or get pins and needles whilst doing this. These are normal side-effects and will go away when they have stopped taking the deep breaths.

We will ask about any health problems which would make the deep breathing unsafe. The deep breathing causes a change in the brain waves and may give extra information to help make a diagnosis.

Hyperventilation is associated with a risk of triggering any clinical event (less than 3 in 100 patients) or seizure (less than 2 in 100 patients). The risk of a generalised tonic-clonic seizure is 3 in 10,000 patients. You will be asked to consent to this part of the test, there is no other way to get the information obtained during hyperventilation.

Illustration of child blowing on a party blower with sticky wires connected to their head

Photic stimulation

A lamp which flashes on and off at different speeds is placed in front of your child. They will be asked to look at it.

In a small percentage of children, the flashing light could trigger a seizure (called photosensitivity). If your child has this response the light is turned off quickly and they would not usually go on to have a seizure. However with photic stimulation there is a risk of less than 2 in 100 patients having any clinical event and 7 in 1,000 patients have a risk of a seizure triggered by the flashing light. The risk of the seizure being a generalised tonic-clonic seizure is 7 in 10,000 patients. You will be asked to consent to this part of the test, there is no other way to get the information obtained during photic stimulation.

Illustration of child looking at images flashing in front of them with sticky wires connected to their head


Your child may go to sleep naturally for a short time whilst they are having the EEG. There are different methods of sleep deprivation in use but the risk of triggering a seizure after sleep deprivation is less than 6 out of 100 children. You need to understand and consent to this risk before undertaking for your child to have less sleep the night prior to the appointment.


Please note: we routinely video the test in case your child has any symptoms or seizures that we need to re-examine. Video clips of any symptoms or seizures are kept as part of the recording. When the doctor has completed the report the remaining video is deleted. We will ask for your consent to do this. We may also ask for permission to use the video for teaching purposes, you would be asked to consent separately for this. 

What happens after the test?

Once the test is finished, we will take the discs off. You may find a small amount of paste in their hair but this washes out easily with shampoo. You may like to bring a hat or cap for them to wear.

Illustration of child with their thumbs up and a smiley face sticker on their jumper

When will I get the results?

You will not get the results on the day of the test because it takes time to analyse them. The report will go to the referring consultant in 2 to 5 working days. They will discuss the results with you.

How do I find out more information?

We will always ask for your consent before for any procedure takes place. Staff will explain all the risks benefits and alternatives before they ask for your consent.

If you have any questions or worries after reading this information please ring the Department of Clinical Neurophysiology on:
0114 271 3237, open Monday to Friday from 8.30am to 4.30pm.

Is something missing from this resource that you think should be included? Please let us know

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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: NPS3

Resource Type: Article

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