• Plasma levels of cortisol were sampled for 24 hours in 32 endogenously depressed (ED) patients and 72 controls to examine mean 24-hour plasma levels of cortisol, intervention in the feedback mechanism of the hypothalamic-pituitaryadrenal system (the dexamethasone suppression test), the circadian rhythm of cortisol secretion and its magnitude, and the ultradian rhythm of cortisol secretion. The main difference in the pattern of cortisol secretion in ED patients, as compared with controls, was in the ultradian rhythm. No acrophase or nadir advance of cortisol secretion in endogenous depression was found when age was controlled, but there was an earlier timing of first secretory episode of cortisol (during night). Only some ED patients have abnormalities in each of the functions studied, and they only partially overlap each other. The results suggest that abnormal cortisol secretion in depression should not be viewed as a monolithic malfunction characteristic of endogenous depression.
Halbreich U, Asnis GM, Shindledecker R, Zumoff B, Nathan RS. Cortisol Secretion in Endogenous DepressionII. Time-Related Functions. Arch Gen Psychiatry. 1985;42(9):909-914. doi:10.1001/archpsyc.1985.01790320081011