Understanding sleep ontogeny to assess brain dysfunction in neonates and infants.

The ontogenetic framework onto which a child's sleep is constructed undergoes significant developmental alterations during early life. Sleep state behaviors, in large part, reflect continuities from fetal through neonatal time periods. Major changes in sleep organization subsequently occur throughout infancy. Maturational expressions of sleep behaviors must be understood by the pediatric neurologist before specific physiologic phenomena can be assessed as transient sleep disturbances or clinically relevant sleep disorders. The first part of this two-part review article focuses on the major aspects of developmental sleep physiology in the first few months of life. Recognition of age-specific electroencephalographic/polysomnographic patterns will facilitate the child neurologist's evaluation of the newborn with suspected seizures and interictal encephalopathies, as well as the prediction of neurologic sequelae.