What is an EEG?
Understand what the recording can tell you — and why the result is only one part of the story.
What an EEG does
An electroencephalogram (EEG) records electrical signals using small sensors on the scalp. It records activity; it does not put electricity into your brain. Your team will explain how to prepare, including whether they want you to sleep during the test.
What happens at the appointment?
You may be asked to open and close your eyes, breathe deeply or look at flashing lights. These procedures are explained beforehand because they can bring out useful changes and occasionally provoke a seizure. Tell the team about your concerns and follow their individual instructions.
Can the EEG be normal?
Yes. The recording is a short sample of brain activity. Some people with epilepsy have no relevant changes during a routine test. Your doctor may recommend a sleep, longer home recording or video-EEG if further information would help.
What does an abnormal result mean?
An abnormal result is not automatically epilepsy. Some changes reflect drowsiness, medicines or other brain conditions. Movement and blinking can also affect the recording. Your specialist interprets the test alongside your symptoms and history.
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EEG: the recording, the result and the clinical questionPatient explanations and professional interpretation notes.
Questions you may have
What does an EEG do?
An electroencephalogram (EEG) records electrical signals using small sensors on the scalp. It records activity; it does not put electricity into your brain. Your team will explain how to prepare, including whether they want you to sleep during the test.
What happens at the appointment?
You may be asked to open and close your eyes, breathe deeply or look at flashing lights. These procedures are explained beforehand because they can bring out useful changes and occasionally provoke a seizure. Tell the team about your concerns and follow their individual instructions.
Can an EEG be normal in epilepsy?
Yes. The recording is a short sample of brain activity. Some people with epilepsy have no relevant changes during a routine test. Your doctor may recommend a sleep, longer home recording or video-EEG if further information would help.
Does an abnormal EEG always mean epilepsy?
An abnormal result is not automatically epilepsy. Some changes reflect drowsiness, medicines or other brain conditions. Movement and blinking can also affect the recording. Your specialist interprets the test alongside your symptoms and history.
Read the guide in depth
What an EEG does
An electroencephalogram (EEG) records electrical signals using small sensors on the scalp. It records activity; it does not put electricity into your brain. Your team will explain how to prepare, including whether they want you to sleep during the test.
What happens at the appointment?
You may be asked to open and close your eyes, breathe deeply or look at flashing lights. These procedures are explained beforehand because they can bring out useful changes and occasionally provoke a seizure. Tell the team about your concerns and follow their individual instructions.
Can the EEG be normal?
Yes. The recording is a short sample of brain activity. Some people with epilepsy have no relevant changes during a routine test. Your doctor may recommend a sleep, longer home recording or video-EEG if further information would help.
What does an abnormal result mean?
An abnormal result is not automatically epilepsy. Some changes reflect drowsiness, medicines or other brain conditions. Movement and blinking can also affect the recording. Your specialist interprets the test alongside your symptoms and history.