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What is an EEG (including nap time EEG’s)?

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 an EEG help?

EEG may help us in the diagnosis of a variety of illnesses.

How it helps depends on the problems that your child is having. For example, they may be having blackouts or seizures. The EEG may find the cause of the problem and this helps the doctor to provide the best treatment for them.

How long will we be at the hospital?

You will be at the hospital for about 1 to 1.5 hours.

Where will the test be done?

The test is performed in a recording room on E Floor, Grey Stair 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, we are not able to allow 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 Stairs or 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?

  • Make sure that your child has something to eat before their test. If the appointment is in the morning they should have a good breakfast. If it is in the afternoon, they should have some lunch.
  • It is important that their hair is clean and free from hairspray or gel.
  • Please continue with any medication they are currently taking. It is helpful if you bring a list of their current medications with you.
  • Make sure they wear loose comfortable clothing so we can access their arms and legs if necessary.
  • 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?

To prepare them for the test, your child’s head may be measured. We then rub the head with a cotton bud dipped in abrasive paste.

Sticky paste is used to hold the 23 small discs in place to pick up their brain waves. Getting them ready for the test takes about 20 minutes and you can ask any questions you have during this time.

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

What happens during the test?

The test takes about 20 to 30 minutes and your child will not feel anything whilst the EEG is recorded. Older children find that they are most comfortable lying down.

Babies and younger children may sit on a parent’s knee or on a chair to watch TV or play with toys. We see children of all ages and abilities.

Please bring favourite items to distract them during the set up such as blankets, drinks, snacks, a dummy and toys or music and DVDs if you think they will help to calm them.

When your child is comfortable we connect the discs to the computer to record the brain waves. Sometimes we may put a gauze hat on to keep the discs in place. 2 stickers put on their arms or shoulders record their heart rate (ECG). Several additional stickers are put on to record muscle movements.

Illustration of child laid down with wires connected to their head


Please note a video recording is part of a routine EEG test in case your child has any symptoms or seizures which need to be re-examined. Video clips of such symptoms or seizures are are kept as part of the recording. When the doctor has completed the report the remaining video is deleted. We will ask your consent for this. We may also ask consent to use the video for teaching purposes and consent would be taken separately for this. 

During the test, the technician will ask them to do various simple actions like:

Opening and closing their eyes, hyperventilation and photic stimulation.


This is when you take 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

What is a nap time or sleep EEG?

Sometimes your child may be asked to attend for a nap time EEG or the child may happen to fall asleep naturally for a short period whilst they are in the department. This can give us extra information. If your child needs to have an EEG during their usual nap time, we will arrange a suitable time with you that fits with your usual schedule.

Please do not let your child sleep on the way to the appointment. You may need someone else to help if you are driving to the appointment to keep them awake.

Please make sure to bring comforters with them which usually enable them to settle, such as blanket, teddy, or bottle. It also helps to dress your child in loose clothing or their pyjamas to be comfortable.

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 are unsure about any aspect of the procedure proposed, please do not hesitate to ask for more information.

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: NPS2

Resource Type: Article

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