EFFECTS OF TEMPERATURE ON SLEEP IN THE DEVELOPING RAT

In altricial species, such as humans and rats, much of the development of autonomic systems occurs postnatally. Consequently, vulnerabilitie s exist early in postnatal development when immature autonomic functio ns are challenged by external factors such as variations in ambient te mperature (T-a). T-a profoundly influences sleep/wake state structure in adult animals and humans, and exposure to excessive warmth has been implicated as a risk factor in sudden infant death syndrome. To bette r understand the relationship between temperature and sleep during dev elopment, we investigated the effect of T-a variation on sleep/wake st ate structure and sleep intensity in developing rats. In this experime nt, sleep intensity was measured by the intensity of slow-wave activit y during slow-wave sleep. Neonatal Long-Evans hooded rat pups were sur gically prepared for chronic sleep/wake state and brain temperature (T -br) recording. Two-hour recordings of sleep/wake state and T-br Were obtained from rats on postnatal day 12 (P12), P14, P16, P18, and P20 a t a T-a of either 28.0-30.0, 33.0-35.0, or 38.0-40.0 degrees C. T-a si gnificantly influenced sleep/wake state structure but had Little, if a ny, effect on sleep intensity in developing rats.