SOMATOSTATIN IMPAIRS SLEEP IN ELDERLY HUMAN-SUBJECTS

With increasing age, sleep becomes move shallow and fragmented and sle ep-associated growth hormone (GH) release declines. GH secretion is re gulated physiologically by opposite actions of GH-releasing hormone (G HRH) and somatostatin (SRIF). The administration of GHRH promotes slee p in both young and elderly controls, whereas SRIF does not induce sle ep-EEG changes in young subjects. Because the influence of peripheral SRIF administration on sleep EEG in the elderly is unknown, we adminis tered 50 mu g SRIF-14 every hour between 2200 and 0100 hours to contro ls with an age range from 60 to 73 years (mean +/- SD 67.4 +/- 5.1 yea rs). After SRIF administration, total sleep time and vapid eye movemen t (REM) sleep decreased significantly, and more time was spent awake i n the first sleep cycle, suggesting that SRIF induces sleep deteriorat ion in the elderly. The peptide may become more effective on sleep EEG in older than in younger subjects, because of the decline of GHRH-GH axis activity, which may contribute to sleep disturbances in aging. Th e increased efficacy of SRIF in the elderly also ?nay be explained by enhanced leakage of the blood-brain barrier. (C) 1997 American College of Neuropsychopharmacology.