The two sides of the brain show different patterns of electrical activity. If flashing lights are used during the test, one area of the brain (the occipital region) may have a brief response after each flash of light. There are no abnormal bursts of electrical activity and no slow brain waves on the EEG tracing. The two sides of the brain show similar patterns of electrical activity. In adults who are awake, the EEG shows mostly alpha waves and beta waves. Theta waves are normally found only in young children and in people who are asleep.Delta waves are normally found only in young children and in people who are asleep.Beta waves are normally found when you are alert or have taken high doses of certain medicines, such as benzodiazepines.Alpha waves go away when your eyes are open or you are concentrating. Alpha waves are present only when you're awake with your eyes closed but you are mentally alert.If an EEG is being done to check a sleep problem, your brain's electrical activity may be recorded all night.ĮEG test results are ready on the same day or the next day. If you can't fall asleep, you may get a sedative to help you sleep. You may be asked to look at a bright, flashing light called a strobe.In most cases, you will take 20 breaths a minute for 3 minutes. You may be asked to take deep and rapid breaths (hyperventilate).The technologist may ask you to do different things during the test to see what activity your brain does at that time. This allows you to stretch and change your position. The recording may be stopped from time to time. The technologist will watch you directly or through a window during the test. You will need to lie still with your eyes closed during the recording. Or the activity may be shown as an image on the computer screen. A machine can show the activity as a series of wavy lines on a piece of paper. The electrodes are hooked by wires to a computer that records the electrical activity in the brain. In rare cases, the electrodes may be attached to the scalp with tiny needles. Instead of separate electrodes, you may wear a cap with several fixed electrodes. A sticky paste is used to hold them in place. The EEG technologist will attach several flat metal discs (electrodes) to different places on your head. Or you may sit in a chair with your eyes closed. You will be asked to lie on your back on a bed or table. The EEG record is read by a doctor who is trained to diagnose and treat problems that affect the nervous system ( neurologist). An EEG may be done in a hospital or in a doctor's office.

Normal vs epilepsy eeg