Temporal coordination of rest-activity cycle, body temperature, urinary free cortisol, and mood in a patient with 48-hour unipolar-depressive cycles in clinical and time-cue-free environments.

During medication-free observation a 66-year-old male patient showed an almost strict alternation of days with depressed mood and days with normal mood. The experiment consisted of two parts; the first was 4 weeks' observation in the psychiatric ward, while the second was 2 weeks' observation in an experimental unit where the patient was deprived of all known information on local time. In the psychiatric ward the observed circadian rhythms, i.e., the rest-activity cycle, the body temperature, the urinary free cortisol, and the mood rhythm, were all synchronized with the geophysical day. Under isolation from time cues the average rest-activity cycle duration was reduced to about 19.5 hr, whereas the body temperature and the urinary free cortisol continued to show rhythms with near-24-hr periods. The main finding of the study is the persistence of a near-48-hr periodicity in the mood fluctuation under isolation from time cues. Besides this, in the time course of body temperature and urinary free cortisol evoked components correlating with the mood cycles were found.