Food restriction alters the diurnal distribution of sleep in rats

The purpose of the present study was to determine the effects of restrictin g food and water intake to the light period on sleep and brain temperature (T-br) Sprague-Dawley male rats were anesthetized and provided with electro des and thermistors for electroencephalographic (EEG) and T-br recordings. Baseline recordings were performed after a 3-week recovery period. After ba seline recordings, access to food and water was restricted (FWR) to the lig ht period for 29 days. During FWR, the diurnal distribution of rapid-eye-mo vement sleep (REMS) and T-br were reversed, while the distribution of non-R EMS (NREMS) between the dark and light periods was attenuated. Daily food a nd water intake, body weight, and the diurnal distribution of EEG slow-wave activity within NREMS remained unchanged. In a separate study, sham-operat ed and pinealectomized rats were studied in a similar manner. The sleep res ponses of pineal-ectomized and sham-operated rats to FWR were similar. Furt her, FWR did not affect melatonin levels in the sham-operated rats, thereby suggesting that the pineal gland does not mediate the effects of FWR on sl eep. (C) 1999 Elsevier Science Inc.