ABSTRACT
This chapter examines the consequences of complete temporal isolation of subjects confined to caves or bunkers in the "free-running" condition. Spatial isolation may involve temporal isolation if one is completely deprived of the means of temporal estimation and orientation usually provided by the environment. There are many cues to temporal orientation. They originate in the natural environment, and the most important is the succession of days and nights. To this fundamental rhythm are added all the landmarks related to the social organization of life: mealtimes, school and work hours, and signals that occur on a regular schedule, such as the passing of trains and the ringing of church bells. The circadian RT rhythm is similar to that found by Kleitman for different sensorimotor tasks, with a minimum RT in the forenoon, and two maximums, one at the beginning and one at the end of the wakefulness period.
