Ghrelin enhances the nocturnal secretion of cortisol and growth hormone in young females without influencing sleep

SummaryGhrelin was shown to increase slow wave sleep (SWS) and the secretion of growth hormone (GH) and cortisol in young males. In terms of sleep, such information for females, however, is lacking. Therefore, polysomnographies were recorded (23:00–07:00 h) and nocturnal (20:00–07:00 h) secretion profiles of GH and cortisol were determined in 10 healthy females (24.9±2.4 years, body mass index: 21.2±1.1) twice, receiving four boluses of 50 μg ghrelin or placebo at 22:00, 23:00, 00:00, and 01:00 h, in this single-blind, randomized, cross-over study. No significant differences of conventionally or quantitatively analyzed sleep were observed between ghrelin and placebo condition. First administration of ghrelin caused a marked mean increase of GH by 53.3 to 64.4±14.2 ng/ml (placebo: 5.9±1.5 ng/ml) and cortisol by 54.2 to 96.4±15.3 ng/ml (placebo: 27.5±4.7 ng/ml). The following ghrelin injections were associated with smaller increases of GH and cortisol. In the ghrelin condition, GH plasma levels remained significantly (P<0.05) higher from 22:20 to 02:00 h and cortisol plasma levels from 22:20 to 02:20 h. In contrast to findings in young men, ghrelin did not affect sleep in young women, indicating a sexual dimorphism. In accordance with the findings in young men, ghrelin stimulated secretion of GH and cortisol.