Fetal exposure to narcotics: neonatal sleep as a measure of nervous system disturbance.

Newborn infants, chronically exposed in utero to low doses of methadone with or without concomitant heroin, display more rapid eye movement sleep and less quiet sleep than control infants, while babies fetally exposed to both opiates and nonopiates have less organization of sleep states. Other perinatal factors, such as birth weight and gestational age, are related more to the amount of fetal drug exposure than to the type.