Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content

Electroencephalogram (EEG)

5-minute read

Key facts

  • An electroencephalogram (EEG) is a test that records your brain activity.
  • It can be used to diagnose different conditions such as epilepsy or sleep disorders.
  • To prepare for an EEG, your hair should be clean and dry.
  • During an EEG, discs called electrodes will be placed on your scalp to measure your brain waves.
  • An EEG is non-invasive and does not hurt.

What is an EEG test?

Your brain cells produce electric signals to communicate with each other and the rest of your body. An electroencephalogram, or EEG, is a test that measures the electrical activity of your brain.

This electrical activity is recorded by placing flat metal discs (electrodes) on your scalp. The activity recorded is then shown on a computer as ‘brain waves’.

If something is unusual about your brain’s electrical activity, it will show up in the EEG recording. A specialist doctor can look at these brain waves to help diagnose different conditions.

Sometimes, unusual brain activity happens when we are tired or asleep. Because of this, some EEG tests are done while you are sleep deprived.

When is an EEG used?

Your doctor may recommend an EEG to help diagnose or monitor conditions such as:

It can also be used to diagnose different sleep disorders, such as:

While an EEG can diagnose epilepsy, a normal EEG test does not rule out epilepsy. This is because brain activity can return to normal between seizures.

How do I prepare for an EEG test?

When having an EEG, it’s best that your hair is clean and dry. Wash your hair the day before your test. This will help the discs stay attached to your scalp. Avoid using hair products such as:

  • conditioners or hair oil
  • hairsprays
  • styling gels

Your doctor will let you know if you need to stop taking any of your medicines before the test.

Your doctor may ask you to do a sleep deprived EEG. If so, you will need to stay awake the night before your test without the help of caffeine or sugar. If you are having a sleep deprived EEG, you should not drive to your appointment.

What happens during an EEG?

An EEG is usually done in a hospital, on an EEG ward. During the EEG, discs will be placed all over your scalp (head). They are usually kept in place with a sticky paste that can be easily washed out of your hair.

The discs will be attached to wires which send electrical signals to a computer. The computer will record your brain waves. You won’t feel any sensations from the discs. You will need to keep still during the test.

If your child needs an EEG, you can bring things to keep them distracted and relaxed, such as:

  • something to watch
  • their favourite blanket

During an EEG, you may be asked to do some deep breathing or look at a flashing light. If you have had a sleep-deprived EEG, you may be asked to sleep during the test.

An EEG usually takes about an hour but may be longer for a sleep recording.

What are the possible risks of an EEG?

An EEG is a safe, non-invasive test that does not hurt.

The discs used during an EEG only record electric signals, they do not produce them. This means there is no risk of electric shock.

Sometimes, an EEG can cause a seizure if you or your child has a condition that causes seizures. You can talk to your doctor about any concerns you may have before having an EEG.

Resources and support

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: August 2022

Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Electroencephalogram (EEG) -

An electroencephalogram (EEG) is a test that records electrical signals within the brain, and can be used to diagnose several conditions, including epilepsy.

Read more on myDr website

EEG test - Better Health Channel

In a person with epilepsy, an electroencephalogram (EEG) may show bursts of abnormal discharges in the form of spikes and sharp wave patterns.

Read more on Better Health Channel website

Somatosensory Evoked Potential (SSEP) | myVMC

A somatosensory evoked potential (SSEP) is an evoked potential caused by a physical stimulus (usually a small electric pulse). Electrodes positioned over particular areas of the body record responses of the SSEP, these are then observed as a reading on an electroencephalogram (EEG).

Read more on myVMC – Virtual Medical Centre website

Visual Evoked Potential (VEP) | myVMC

A visual evoked potential is an evoked potential caused by a visual stimulus, such as an alternating checkerboard pattern on a computer screen. Responses are recorded from electrodes that are placed on the back of your head and are observed as a reading on an electroencephalogram (EEG).

Read more on myVMC – Virtual Medical Centre website

Brainstem Auditory Evoked Potential (BAEP) | myVMC

A brainstem auditory evoked potential (BAEP) is an evoked potential caused by a sound, usually a series of 'clicks'. Electrodes positioned on the scalp record responses to the sounds; these are then observed as a reading on an electroencephalogram (EEG). Responses to aural stimuli originate from relay structures within the brainstem.

Read more on myVMC – Virtual Medical Centre website

Epilepsy and Sleep | Sleep Health Foundation

This is a fact sheet about Epilepsy and Sleep. Epilepsy & sleep are closely interconnected: sleep patterns & disturbances can significantly impact epilepsy while epilepsy can also affect sleep quality

Read more on Sleep Health Foundation website

Neurophysiology (brain and nerve) disorders information | myVMC

Discover information about neurological conditions such as hyperhidrosis, epilepsy and multiple sclerosis, and learn about neurological investigations.

Read more on myVMC – Virtual Medical Centre website

Understanding Epilepsy | Epilepsy Action Australia

Understanding Epilepsy - Anyone can have a seizure under certain circumstances and not all seizures result in a diagnosis of epilepsy.

Read more on Epilepsy Action Australia website

Can a basic brain scan predict stroke outcomes? | The George Institute for Global Health

New research published in the Journal of Neurology, Neurosurgery & Psychiatry confirms the life-saving value of a simple brain scan in identifying the early signs of stroke and the best treatment, and helping clinicians predict the likely severity of the outcome, including risk of death and disability.

Read more on The George Institute for Global Health website

Creutzfeldt-Jakob disease | SA Health

Creutzfeldt-Jakob disease and the variant form are fatal infections of the brain - there is no available vaccine or treatment

Read more on SA Health website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Queensland Government logo Government of South Australia, health department logo Tasmanian government logo Victorian government logo Government of Western Australia, health department logo

Healthdirect Australia acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to land, sea and community. We pay our respects to the Traditional Owners and to Elders both past and present.