Circadian variations in behavioral and biological sensitivity to ethanol.

In rats, behavioral (startle response and motor activity) and physiological (plasma corticosterone, nonesterified fatty acids, blood ethanol levels, liver alcohol and aldehyde dehydrogenase activity, and body temperature) responses to ethanol were measured over the 24-hr cycle. The response to ethanol for many of these measures showed circadian variations. Both stimulatory and inhibitory effects of ethanol were observed for several dependent variables at the same time, relative to controls. These results suggest that many discrepancies in the ethanol literature may be due to a light cycle X dependent variable interaction.