The activity of 10 female rats was measured for 50-day periods in a revolving wheel and a stationary cage. Activity cycles appeared to be longer and more variable in the cage. The increases representing estrus were proportionately greater in the wheel, but the difference between the effect of estrus upon the 2 activity scores is less than the difference observed with food deprivation. From Psyc Abstracts 36:05:5EF24F. (PsycINFO Database Record (c) 2006 APA, all rights reserved)