An animal model for pregnancy-associated sleep disorder.

We studied basic sleep changes in pregnant rats in order to understand how pregnancy alters sleep. In the rat, pregnancy increased nocturnal nonREM sleep across the entire period but increased REM sleep only in the early period. By the end of pregnancy, diurnal sleep was decreased, showing that pregnancy in rats causes biphasic sleep changes as it does in humans. Termination of pregnancy returned the enhanced sleep to baseline as in the estrous cycle. Therefore, significant changes in the pattern of sleep occurred during pregnancy in rats, suggesting that the animal model may contribute to understanding the mechanism of sleep disorders related to human pregnancy.