Electroencephalography (EEG)

What is Electroencephalogram (EEG)?

Electroencephalogram (EEG) involves placing small electrodes on your scalp to record the electrical activity of your brain.

The information obtained from an EEG is used to diagnose seizure- and epilepsy-related conditions, and to guide treatment.

Your doctor may recommend an EEG to: 

• Evaluate seizures or epilepsy 
• Assess sleep disorders 

The above list is non-exhaustive and there may be other reasons for your doctor to recommend an EEG. 

How should I prepare for EEG?

Before the day of EEG

• Avoid smoking and drinking caffeinated beverages, e.g. coffee, tea, at least 8 hours before the test.
• Continue with your regular diet and medications (unless instructed differently by your doctor). There is no need to fast.
• If you have been informed by your doctor to attend a sleep-deprived EEG, please sleep < 4 hours the night before the test.

Please note that the test cannot be done if:

• You have headlice.
• You have an object on your head that cannot be removed and which interferes with EEG recording (such as a non-removable wig).

On the day of EEG

• Wash and dry your hair before your appointment. Avoid conditioner and hair styling products (e.g. foam, cream, gel, oil).
• Bring all your medications and note down the name and dosage of the medications you are taking.
• There is no need to fast.

How is EEG performed?

• The EEG is performed by a neurotechnologist. A routine EEG typically takes about 1 hour (including preparation time).
• This test is done while you are lying down (face up) on a bed.
• Your scalp is cleaned using gel. 
• Small markings are made on your scalp.
• 27 electrodes are attached to the marked areas using a safe and washable paste.
• The electrodes are connected to a machine to record your brain’s electrical activity. For accurate test results, close your eyes and remain still, unless otherwise instructed. Note that even subtle movements in the head and neck region during the EEG recording (such as excessive blinking, excessive talking, or clenching your teeth), can influence the results of the EEG, making it harder to interpret.
• Simultaneously, a video is typically recorded, so that any seizures can be captured on video and correlated with real-time brain activity. 
• At different times during the EEG, you may be asked to open and close your eyes, look at flashing lights, breathe deeply and rapidly for several minutes, and/or answer some questions.
• Once the EEG recording has been completed, the electrodes are removed, the paste is cleaned, and you can leave the EEG recording room.
• The procedure is not expected to cause any pain to you.
• A detailed report will be sent to your doctor within two weeks. Your doctor will discuss the findings with you at your next appointment. 

Frequently Asked Questions about EEG

Is the test safe?

Yes. 

• EEG is non-invasive. No needles or instruments will penetrate your skin. 
• EEG does not involve any external electric current or discharges. The test only records your brain’s electrical activity – it does not send electricity into your body.
• The electrodes are temporary and will be removed, leaving no lasting side-effects.
• A neurotechnologist will be present throughout the process. If you feel unwell, please inform the neurotechnologist.

Do I need to shave my hair? 

No. You just need clean and dry hair, without any oils, sprays or gels.

Can I drive after the test? 

Most people can drive and return to normal activities immediately after the test, unless your doctor advises otherwise.

Can I use Medisave to pay for this test? 

This test may be claimable under:

• Flexi-MediSave for Seniors; or
• Outpatient scans for diagnosis or treatment of a medical condition.

Please refer to the Ministry of Health's Outpatient Care page for the latest claim limits and eligibility criteria. 

The information is correct as of July 2026 and subject to revisions without notice.
Content adapted from NNI Neurodiagnostic Laboratory (NDL), NNI@TTSH.