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An electroencephalogram (EEG) measures the electrical activity in your brain. An EEG can help caregivers diagnose brain conditions such as seizures and brain tumors.


Before your EEG:

  • Do not drink or eat any caffeine the morning of the procedure. Caffeine may change the result of your EEG.
  • Eat a regular meal before the EEG. This will help prevent your blood sugar from dropping too low. Low blood sugar can change the result of your EEG.
  • Informed consent is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.
  • Your caregiver may give you medicine if he wants you to sleep during the EEG.

During your EEG:

  • Your EEG will be done in a room that is dark and quiet. You will either lie in a bed or sit in a reclining chair during the procedure. A caregiver will clean 20 to 21 areas of your scalp. Then, a gel or cream will be placed on these areas. Electrodes (sensors) will be placed on the gel or cream. The electrodes will be connected with wires to a machine or computer. An electrode may also be put on each earlobe.
  • Lie very still with your eyes closed. Try to relax. Do not talk during the test. The EEG machine or computer will record your brain waves. During the EEG, you may need to breathe deeply and quickly for 3 to 4 minutes. You may be asked to look into a bright flashing light. You may be videotaped during the EEG.

After your EEG:

The electrodes and wires will be removed. A caregiver will remove the cream or gel from your scalp and hair. Most EEGs are done in 90 minutes or less. Your caregiver may talk to you about the EEG results before you leave. Your caregiver may send a letter to you explaining the EEG results within 7 days.


The flashing light or fast breathing may cause a seizure during the EEG. Trained caregivers will be there to help you. If you do not have this procedure, caregivers may not be able to treat your illness.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.