0224 Sleep Disruption Due To Environmental Noise Exposure Increases Weight Gain By Modulating Energy Intake And Expenditure In Intact Female Rats

Abstract

Abstract Reducing either sleep time or quality increases obesity in humans. Current data suggest that women exhibit higher susceptibility to weight gain following sleep restriction relative to men, though this is unconfirmed. In male rats, we demonstrated that exposure to environmental noise (8h/d, 9-d during the light cycle) reduced sleep and increased sleep fragmentation, food intake and weight gain while acute exposure (12h/d, 1-d during the light cycle) reduced total energy expenditure (TEE) and its components. However, whether this method of sleep disruption (SD) produces a similar effect in intact female rats, and if the estrous cycle influences this, remains unknown. EEG, EMG, physical activity, TEE and its components were recorded from intact female Sprague-Dawley rats throughout a baseline (9-d), noise exposure (8h/d, 9-d during the light cycle) and recovery period (9-d). Estrous cycle phase was determined daily by cytology. Bodyweight gain and food intake was measured in a separate set of intact female rats that were either exposed to noise (8d/h, 17-d during the light cycle) or slept undisturbed. Females had normal 4 to 5-d cycles throughout the study, but all endpoints (sleep duration, sleep fragmentation, physical activity, TEE and its components) showed significant variation across the estrous cycle in both the light and dark cycle. In female rats, noise exposure significantly reduced sleep and increased wakefulness and sleep fragmentation in the light cycle and 24h period as well as subsequently significantly increased sleep in the dark cycle and during the recovery period. TEE was significantly lower during both noise exposure and recovery due to lower energy expenditure from physical activity and in sleep. In the separate group of intact females, noise significantly increased bodyweight gain and feeding compared to controls. As in males, noise-induced SD increases weight gain in female rats without disrupting estrous cycle length, which suggests that this method of SD will be useful for examining whether sex interacts with weight gain due to sleep disturbance. University of Arizona.