Ghrelin promotes slow-wave sleep in humans.
J C Weikel1, A Wichniak, M Ising
1Max Planck Institute of Psychiatry, Department of Psychiatry, 80804 Munich, Germany.
American Journal of Physiology. Endocrinology and Metabolism
|October 22, 2002
Summary
Ghrelin administration in humans significantly altered sleep patterns, increasing slow-wave sleep and enhancing growth hormone (GH) and prolactin secretion. These findings suggest ghrelin acts as an endogenous sleep-promoting factor.
Area of Science:
- Endocrinology
- Sleep Medicine
- Neuroscience
Background:
- Ghrelin, the endogenous ligand for the growth hormone secretagogue (GHS) receptor, is known to stimulate GH release, appetite, and weight gain.
- Synthetic GHSs have been shown to influence sleep electroencephalogram (EEG) and nocturnal hormone secretion.
Purpose of the Study:
- To investigate the effects of exogenous ghrelin administration on sleep EEG and the secretion of key hormones (GH, ACTH, cortisol, prolactin, leptin) during nighttime in humans.
Main Methods:
- Seven human participants received intravenous boluses of ghrelin (4 x 50 microg) hourly between 2200 and 0100.
- Sleep EEG parameters and plasma levels of GH, ACTH, cortisol, prolactin, and leptin were monitored.
Main Results:
- Ghrelin administration increased slow-wave sleep and enhanced delta-wave activity during the latter half of the night.
- Rapid-eye-movement (REM) sleep was reduced in the second third of the night.
- Plasma levels of GH and prolactin increased throughout the night, while cortisol levels rose in the early part of the night. GH response diminished with repeated injections, whereas cortisol response showed an inverse pattern. Leptin levels remained unchanged.
Conclusions:
- Exogenous ghrelin distinctly impacts sleep EEG and nocturnal hormone secretion in humans.
- Ghrelin is proposed to be an endogenous sleep-promoting factor, complementing its role in energy balance regulation.
- Ghrelin acts as a common stimulus for the somatotropic and hypothalamo-pituitary-adrenocortical systems.
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