To see if the EEG is normal or not, we have to take into account the age and the usual sleep situation to determine if the EEG is normal or not. In adults, the EEG is dominated by alpha waves, and slow waves may appear after sleep. In adolescents, slow waves are predominant because the brain is not fully developed. After the age of 14, brain tissue close to that of adults can be seen to be dominated by alpha waves. In older patients, because of the decreasing brain function, some older patients can also see some of the slow waves, such as delta waves. Whether the EEG is normal or not depends on the specific age of the patient.