Cafeteria diet promotes sleep in rats.

Sleep patterns were continuously recorded in male Wistar rats receiving a palatable, mixed, high-energy diet with chow for ten consecutive days. Results were compared with sleep data obtained from the same rats when offered only normal laboratory chow. The "cafeteria" choice of diets resulted in a significant increase of the daily duration of both slow wave sleep (SWS) and paradoxical sleep (PS). SWS was increased during the light and dark phases of the day-night cycle, whereas PS was augmented only during the light phase. The increased sleep duration was mainly due to a significant lengthening of the respective episodes. When the cafeteria-diet was withdrawn, SWS and PS remained elevated for 3 days and 1 day, respectively before returning to normal levels. The present findings are discussed with regard to present knowledge of sleep mechanisms. A possible role of increased sleep in the development of obesity is also suggested.