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Acute cortisol administration promotes sleep intensity in man.
Elisabeth Friess1, Hirokuni Tagaya, Claus Grethe
1Max Planck Institute of Psychiatry, Munich, Germany. friess@mpipsykl.mpg.de
Summary
Cortisol administration increases slow-wave sleep by enhancing synchronized brain activity, particularly delta and theta frequencies. This effect on sleep intensity and growth hormone secretion appears to involve different underlying mechanisms.
Area of Science:
- Neuroscience
- Sleep Science
- Endocrinology
Background:
- Neuronal mechanisms of non-REM sleep synchronization are increasingly understood.
- Previous research indicates cortisol increases slow-wave sleep (SWS) and decreases REM sleep.
- Elucidating cortisol's non-REM sleep effects requires sleep-state-specific quantitative EEG analysis.
Purpose of the Study:
- To investigate the effects of repetitive hydrocortisone injections on sleep EEG spectral composition.
- To assess the relationship between sleep EEG changes and sleep-associated growth hormone (GH) secretion.
Main Methods:
- 10 healthy young males received repetitive hydrocortisone injections.
- Quantitative EEG analysis was performed on sleep recordings.
- High-frequency blood sampling monitored GH levels.
Main Results:
- Cortisol significantly increased synchronized EEG activity (delta and theta frequencies), correlating with increased SWS.
- This effect was most pronounced in the early hours of nocturnal sleep.
- REM sleep decreased, likely secondary to a prolonged first sleep cycle.
- Cortisol-induced GH release did not correlate with increased SWS.
Conclusions:
- Cortisol enhances sleep intensity through increased cortical synchronization.
- Sleep-associated GH secretion and sleep intensity changes are regulated by distinct mechanisms.
- Negative feedback inhibition of endogenous corticotropin-releasing hormone (CRH) may mediate cortisol's sleep effects.