Intake of water and ethanol by C57BL mice: effect of an altered light-dark schedule.

Mice of the C57BL/6J strain were given unrestricted access to food, water, and ethanol-water solutions, and intake was studied under different light-dark (LD) conditions. The instrumentation for recording licks permitted the accurate description of the temporal distribution of drinking over the 24-hr period. The 12-12 LD schedule resulted in a consistent pattern of licking for the three solutions, and this pattern was altered by the subsequent change to a 6-6 LD condition. The intake of ethanol, and the preference for ethanol relative to water, were reduced during the 6-6 condition. The distribution of drinking was circadian to period, though not sinusoidal in form.