ACTH, cortisol and growth hormone 24-hour profiles in major depressive illness.
Circadian rhythms of ACTH, cortisol and growth hormone have been studied in eighteen major depressives (eight unipolar and ten bipolar) as well as in eight normal controls. Both unipolar and bipolar depressed patients secreted more growth hormone than normal men. This hypersecretion occurred during waking hours rather than during sleep. An early sleep GH increase was found in all but one of the normal men, but was absent in seven of the eight unipolar depressed patients, who had instead a presleep increase. No consistent disturbance of the temporal association between sleep onset and GH secretion was found in bipolar depressed patients. Both unipolar and bipolar depressed patients had higher 24 h mean cortisol levels than normal men, but no significant difference was found for 24 h ACTH levels. An early timing of the nadir of ACTH-cortisol secretion which was observed in our depressed patients also suggest that disorders of circadian time keeping may characterize major endogenous depression.