Psychophysiologic circadian rhythmometry on manic-depressive twins.

Rhythmometry on emotionally disturbed identical twins is applied for study of possible emotional chronopathology. Several circadian rhythmic variables are apparently 24-h synchronized in both twins, during a study span associated with mania in one twin and apparently 'normal' behavior in the other. While the data span of 3 weeks does not allow validation of any desynchronization with a period quite near to 24 h in the case of a manic girl, it does not rule out the possibility of uncoupling of an adrenal cortical cycle, gauged by the circadian rhythm in urinary 17-ketosteroid excretion. The question whether circadian or other dyschronism was present, and, if so, represented a trivial corollary or, perhaps, a determinant of emotional pathology, remains unanswered. The methodology here illustrated and added tests of differences in rhythm characteristics are likely to provide answers to such questions when they are combined with therapeutic manipulations and the search for possible chronobiotic drugs.