This leaflet answers common questions about your child having an electroencephalogram (EEG). If you would like further information or have any worries, please ask the physiologist performing the test.

A physiologist will explain the EEG to you on the day of the appointment and answer any questions you may have.

What is an EEG?

An EEG is a recording of electrical signals produced naturally in the brain, ideally whilst your child is drowsy and asleep. This test helps us understand if there are any abnormalities with brain function and can help us see if your child has a higher risk of having seizures.

What will happen during the EEG?

We start by measuring your child’s head and then gently rub certain points on the scalp with some gel, before attaching some small metal discs to their head using a sticky paste. We use long wires to connect the metal discs to a computer to record the brain waves.

Dependent on their age, your child may be asked to follow instructions such as opening and closing their eyes, do a deep breathing exercise and to look at a flashing light.

We would like for your child to relax and, ideally, fall asleep for a short time. A camera will take a video recording of your child throughout the test. You will need to inform the physiologist prior to the EEG if you do not agree to the video recording.

The test may take up to two hours and will be carried out in the neurophysiology department at Royal Free Hospital on the first floor, behind clinic 2.

Before the test

Your paediatric consultant may recommend we provide you with melatonin to give to your child, to help them fall asleep during the EEG. Melatonin is a naturally occurring substance which is produced by the brain at night and helps us fall asleep.

This will be provided to you in the department on the day of the test in the form of a small, crushed tablet. We advise that you bring a small amount of your child’s favourite juice or yoghurt so that the melatonin can be combined with it.

After the test

The results of your child’s test will be sent to the clinician who requested the test. We will not be able to provide a report on the day of the test as the study needs to be analysed.

Risks and side-effects

EEGs are safe tests, which usually have minimal or no side effects. A small number of patients have allergic skin reactions. If your child is sensitive to cosmetics, lotions or sticky tape please inform the physiologist performing the test.

A small number of people are sensitive to flashing lights or deep breathing which may increase the likelihood of having a seizure. This is rare. We will discuss this with you and obtain verbal consent on the day of the test. The physiologist who monitors the EEG during the test will stop the light if your child appears to be sensitive to it.