DESYNCHRONIZATION OF CIRCADIAN RHYTHMS WITHIN AN ISOLATED GROUP

In order to test, whether social interaction is sufficient for synchronization of circadian rhythms, a group of 4 male subjects was isolated. The subjects lived for three weeks under constant conditions in an underground bunker. For each subject were measured: periods of sleep and wakefulness, volume (ml/hr) and concentration of electrolytes of each urine sample and body temperature during sleep. On several days the subjects were tested with psychological questionnaires. During the first half of the experiment, the subjects lived synchronized with each other; they had an average activity period of 26.2 hrs. In the second half of the experiment, 3 subjects lengthened their activity period to 27.2 hrs. One subject lived with a shorter activity period (24.1 hrs) desynchronized from the group. The increase of body temperature during sleep and the course of urine excretion, which is interpreted as beat, indicate that this subject was in fact synchronized in his activity period with the group during the first half of the experiment, but that the rhythm of the vegetative functions was free running with another period (internal desynchronization). © 1968 Springer-Verlag.