EFFECTS OF TIME-OF-DAY AND PHOTOPERIOD PHASE-SHIFTS ON VOLUNTARY ETHANOL-CONSUMPTION IN RATS

Two experiments were conducted to examine the circadian fluctuations i n voluntary ethanol (ETOH) consumption in male Sprague-Dawley rats con ditioned to consume ETCH in their homecage and exposed to photoperiod phase shifts equivalent to those experienced by humans, Using a mainte nance concentration of 20% w/v ETCH, changes in homecage drinking in 4 2 rats were assessed after photoperiod phase shifts similar to those i nducing ''jet lag'' in humans and after experimenter-induced ''hangove r.'' A single 8-hr photoperiod phase advance significantly increased E TOH intake for three consecutive days, and a single photoperiod phase- delay increased intake only on the day of the phase shift, Acute ETCH withdrawal significantly reduced the voluntary consumption of ETCH for two consecutive days, In a second group of 30 rats maintained to cons ume a lower concentration of 10% w/v ETCH, the long-term effects of '' shift lag'' initiated by repeated photoperiod phase shifting similar t o those experienced by humans working under a rotating work schedule w ere examined, Significant increases in intake occurred over the P-mont h testing period. The significant alterations in voluntary intake init iated by the shift work schedule was related to the significant change s in blood alcohol concentrations.