EFFECTS OF HORMONES ON SLEEP

Administration of hormones to humans and animals results in specific e ffects on the sleep electroencephalogram (EEG) and nocturnal hormone s ecretion. Studies with pulsatile administration of various neuropeptid es in young and old normal controls and in patients with depression su ggest they play a key role in sleep-endocrine regulation. Growth hormo ne (GH)-releasing hormone (GHRH) stimulates GH and slow wave sleep (SW S) and inhibits cortisol, whereas corticotropin-releasing hormone (CRH ) exerts opposite effects. Changes in the GHRH:CRH ratio contribute to sleep-endocrine aberrations during normal ageing and acute depression . In addition, galanin and neuropeptide Y promote sleep, whereas, in t he elderly, somatostatin impairs sleep. The rapid eye movement (REM)-n onREM cycle is modulated by vasoactive intestinal polypeptide. Cortiso l stimulates SWS and GH, probably by feedback inhibition of CRH. Neuro active steroids exert specific effects on the sleep EEG, which can be explained by gamma-aminobutyric acid(A), receptor modulation.