Ghrelin increases slow wave sleep and stage 2 sleep and decreases stage 1 sleep and REM sleep in elderly men but does not affect sleep in elderly women

Ghrelin increases non-REM sleep and decreases REM sleep in young men but does not affect sleep in young women. In both sexes, ghrelin stimulates the activity of the somatotropic and the hypothalamic-pituitary-adrenal (HPA) axis, as indicated by increased growth hormone (GH) and cortisol plasma levels. These two endocrine axes are crucially involved in steep regulation. As various endocrine effects are age-dependent, aim was to study ghrelin's effect on steep and secretion of GH and cortisol in elderly humans. Sleep-EEGs (2300-0700 h) and secretion profiles of GH and cortisol (2000-0700 h) were determined in 10 elderly men (64.0 +/- 2.2 years) and 10 elderly, postmenopausal women (63.0 +/- 2.9 years) twice, receiving 50 mu g ghrelin or placebo at 2200, 2300, 0000, and 0100 h, in this single-blind, randomized, cross-over study. In men, ghrelin compared to placebo was associated with significantly more stage 2 sleep (placebo: 183.3 +/- 6.1; ghrelin: 221.0 +/- 12.2 min), slow wave sleep (placebo: 33.4 +/- 5.1; ghrelin: 44.3 +/- 7.7 min) and non-REM steep (placebo: 272.6 +/- 12.8; ghrelin: 318.2 +/- 11.0 min). Stage 1 sleep (placebo: 56.9 +/- 8.7; ghrelin: 50.9 +/- 7.6 min) and REM steep (placebo: 71.9 +/- 9.1; ghrelin: 52.5 +/- 5.9 min) were significantly reduced. Furthermore, delta power in men was significantly higher and alpha power and beta power were significantly tower after ghrelin than after placebo injection during the first half of night. In women, no effects on steep were observed. In both sexes, ghrelin caused comparable increases and secretion patterns of GH and cortisol. In conclusion, ghrelin affects steep in elderly men but not women resembling findings in young subjects. (C) 2009 Elsevier Ltd. All rights reserved.