- EEG patterns change significantly during prenatal development and early childhood as brain maturation occurs rapidly, especially during the first year of life. - In preterm infants, EEG organization into behavioral sleep states like wakefulness, active sleep, and quiet sleep is seen by 35 weeks gestation. - In full-term newborns, active sleep makes up about 50% of total sleep and is characterized by features like anterior slow dysrhythmia and frontal sharp transients. Quiet sleep shows a trace alternans pattern. - During infancy, features continue developing with sleep spindles and vertex sharp waves emerging between 2-6 months. The theta rhythm in wakefulness localizes to rolandic-occ