Sleep-wake differences in serum prolactin levels in children.

Sleep-wake differences in prolactin serum levels have been studied in 47 prepubertal children of both sexes, aged 1 to 12 years. Sampling has been made in each subject once during wake and once during sleep. The serum levels of prolactin were found to be higher during sleep than during wake (p greater than 0.01). When the children were divided into age groups, a statistically significant difference between wake and sleep was observed in all groups considered, including that with children aged 1 to 2 years. This indicates that the sleep connected rise of prolactin levels occurs very early in chidhood. No sex releated difference either in absolute hormone serum levels or in wake-sleep changes is apparent.