Sleep-related hormone secretion in depressed patients.

Among human subjects, sleep is a time of considerable neuro-endocrine activity and the nocturnal secretion of growth hormone is intimately related to the sleep-wake cycle. In contrast, the hypothalamic-pituitary-adrenal axis of entrained individuals shows a circadian pattern of activity with secretion increasing in the latter part of sleep. A variety of neuroendocrine disturbances have been described in depressed patients who also manifest consistent disturbances in their sleep-wake cycle. The sleep-wake cycle is capable of masking these rhythms and thereby modifying patterns of hormone secretion. The sleep disturbance in depressed patients appears to have little effect on the phase of either cortisol or growth hormone secretion but does reduce their amplitudes.