[The role of neuropeptides in normal and disordered sleep regulation]

The neuropeptides growth hormone-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) play a key role in sleep endocrine regulation. After pulsatile application of GHRH during the first few hours of the night in young normal controls SWS and GH increase, whereas cortisol is blunted. CRH however prompts inverse effects. The balance between these peptides is changed in favour of CRH physiologically during the second time of the night, during the acute episode of depression (due to overactivity of GRH) and in the elderly (due to reduced activity of CHRH). These changes explain the aberrances of sleep endocrine activity in these states, as shallow sleep, low GH and enhanced cortisol.