Diagnostic test · Neurology
EEG (electroencephalogram)
An electroencephalogram (EEG) records the brain's electrical activity using small sensors placed on the scalp. The recording usually takes about 30 to 60 minutes and does not use radiation. A neurologist may use an EEG to help assess seizures, blackouts, and certain other conditions.
Medically reviewed by Dr. Priya Raman, MBBS, MD, DM (Neurology) —
At a glance
The essentials.
- Practice
- Neurology
- Type
- Diagnostic test
- Typical time
- 30 to 60 minutes
The full guide
What it is
An electroencephalogram (EEG) is a recording of the brain's electrical activity. Small metal sensors, called electrodes, are placed on the scalp and connected to a machine that records the signals. The test does not use radiation and does not send electricity into the body.
Why a neurologist may recommend it
A neurologist may recommend an EEG to look into seizures, blackouts, or episodes of altered awareness, and sometimes to help assess other conditions. It is one source of information, used alongside your history and other tests. A neurologist decides whether it is needed.
How to prepare
Wash your hair the night before and do not use oil, gel, or spray, so the sensors stick well. Ask the clinic whether to keep taking your usual medicines. For some EEGs you may be asked to sleep less the night before; the clinic will tell you if this applies.
Safety and what you may feel
An EEG is a low-risk test. The flashing light and deep breathing can, rarely, bring on a seizure during the recording; staff are present throughout. An EEG records activity only during the recording, so a normal result does not rule out a condition. If you feel unwell before your appointment, tell the clinic. This website is not for emergencies; for a suspected seizure, call 108 or go to the nearest emergency department.
Results and follow-up
A neurologist reviews the recording and explains what it means at a follow-up appointment, together with your history and any other tests. The EEG on its own is not a diagnosis.
Sources
NHS — Electroencephalogram (EEG)
National Institute of Neurological Disorders and Stroke — Health information
Before you come
What to bring and how to prepare
A short checklist to run through before your appointment. If anything here is unclear, call the clinic and ask.
- Wash your hair the night before and do not use oil, gel, or spray, so the sensors stick well.
- Ask the clinic whether to keep taking your usual medicines.
- For some EEGs you may be asked to sleep less the night before; the clinic will tell you if this applies.
What happens
On the day.
What to expect from the moment you arrive to the moment you leave.
before
Getting ready
a technologist measures your head and attaches the electrodes with a paste. This takes a little time and does not break the skin.
during
During the visit
you rest with your eyes open or closed. You may be asked to breathe deeply for a few minutes or to look at a flashing light. A standard recording usually takes about 30 to 60 minutes.
after
Afterwards
the electrodes and paste are removed. You can wash your hair and return to your usual activities. There is no recovery time for a standard EEG.
Before your appointment
Frequently asked questions
Practical answers about preparation, timing and what happens at the clinic.
Does an EEG hurt?
The sensors sit on the surface of the scalp and are held on with paste. The test does not send electricity into the body. Most people find it straightforward, though attaching the sensors takes some time.
How long does an EEG take?
A standard EEG recording usually takes about 30 to 60 minutes, plus time at the start to attach the sensors.
Can I drive to the appointment?
Ask the clinic. If your appointment involves reduced sleep, or if you have blackouts, you may be advised not to drive; the clinic can tell you what applies to you.
Where this fits
Related care and consulting times.
The conditions this is used alongside, and when the consultant sees patients at the clinic.
Consultation hours
- Neurology
- Mon, Wed, Fri, 5:30 PM–8:30 PM.
Medically reviewed by Dr. Priya Raman, MBBS, MD, DM (Neurology) —
Appointments
Plan your visit.
Mon, Wed, Fri, 5:30 PM–8:30 PM.