An electroencephalogram is a biophysical method that allows visualizing and quantifying brain electrical activity. It’s done by placing several electrodes on the scalp on predesignated anatomical points. Researchers or clinicians then interpret the electrical activity of the brain. The patient’s status: awake or asleep, their sleep phase, or cognitive alertness is interpreted by the brain waves on the EEG record. Patients do not experience any pain during this procedure.