Circadian rhythms in food intake and activity in domestic cats.

Examined the daily patterns of food intake and activity in normal and pontile-lesioned adult cats. Food intake in the dark and light phases of the light–dark (LD) cycles was determined separately by weighing the food, and a percentage nocturnal score was calculated. The measure of activity was infrared photobeam interruptions, with the photobeam placed in front of the cages, over the food bowl. No differences between normal and pontile-lesioned Ss were detected for any of the measures. Ss' food intake was influenced by simulated starlight and moonlight conditions and by the presence of humans. Ss in isolation from humans and human noises exhibited random patterns of activity in constant light and free-running circadian rhythms in constant dark. Idiosyncratic differences in entrainment to LD cycles were found among the Ss. The relevance of this variability is noted for studies of photoperiodic phenomena in this species. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)