An electroencephalogram (EEG) is a common diagnostic test that measures and records electrical activity in your brain. Your neurologist might schedule an EEG to:
- Diagnose epilepsy and seizures
- Evaluate symptoms like confusion, dementia, or loss of consciousness
- Study a sleep disorder
Three key facts about EEGs
- EEGs are safe and painless.
- The exam usually takes about an hour.
- In most cases, there are no restrictions before or after the test.
What to expect with an EEG
When you make an appointment, the EEG lab will explain if you'll need to do any preparation before your exam. Often, the only instruction is to arrive with clean, dry hair and no styling products.
The procedure is painless and typically takes about one hour. Your EEG technician will attach about 20 electrodes to your scalp. Each electrode is a small metal disc with thin wires that connect to the EEG machine. The adhesive is a temporary gel that's easy to remove. And don't worry—you won't be asked to shave your head.
During the exam, your EEG technician will ask you to breathe slowly or quickly. They might direct you to open and close your eyes or use flashes of light to monitor how your brain reacts.
There is a strict "No Selfies" rule during an EEG. The exam room must be free of cell phones and other electronic devices.
After your EEG
After the exam, most patients can leave right away with no activity restrictions. If you are deprived of sleep, you will need a ride home.