• We matched patients with affective disorders by sex and age with a healthy control group. The two groups recorded daily measures of hours slept, energy, anxiety, and mood levels for 14 months. We analyzed the data using spectral analysis. We found that both groups had statistically significant infradian rhythms, with the majority having seasonal cycles, and that the patients with affective disorders differed from the control subjects in having a greater amplitude of their periodicities.
Eastwood MR, Whitton JL, Kramer PM, Peter AM. Infradian RhythmsA Comparison of Affective Disorders and Normal Persons. Arch Gen Psychiatry. 1985;42(3):295-299. doi:10.1001/archpsyc.1985.01790260093011