Some features of the dark-light feeding cycle were explored in the rat. A complex daily pattern was shown for rats maintained under natural dark-light conditions, which disappeared within 6-10 days under constant illumination. Under constant illumination conditions the amount of food intake after deprivation of up to 12 hr. was positively related to the duration of deprivation; under natural dark-light conditions, the effect of deprivation depends partially upon the time of deprivation. From Psyc Abstracts 36:01:3EF94S. (PsycINFO Database Record (c) 2006 APA, all rights reserved)