EFFECTS OF OVARIAN HORMONES ON SLEEP AND RECOVERY FROM SLEEP DEPRIVATION IN OVARIECTOMIZED MIDDLE-AGED FEMALE RATS

Abstract

Menopausal symptoms, including sleep problems, occur as a result of reduced production of ovarian hormones in middle-aged women, and are often treated with replacement of these hormones. However, the efficacy of hormone replacement for improving sleep is controversial. We assessed sleep/wake patterns during baseline and recovery following 6 h of sleep deprivation in ovariectomized middle-aged rats treated with oil, estradiol, or estradiol and progesterone. We found that, at baseline, hormone administration reduced rapid eye movement (REM) sleep initiation and non-REM sleep amount, promoting wakefulness, particularly during the dark (active) phase, but that, during recovery following sleep deprivation, hormonal treatment reduced sleep intensity initially and lengthened REM sleep recovery. These results indicate that in middle-aged female rats ovarian hormones modulate baseline and recovery sleep differently, possibly by modulating circadian and homeostatic regulation of sleep in an age-dependent manner.