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J Clin Endocrinol Metab. 1993 Sep;77(3):780-3.

Ethanol inhibits melatonin secretion in healthy volunteers in a dose-dependent randomized double blind cross-over study.

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Department of Physiology, University of Oulu, Finland.


To elucidate the effects of alcohol on pineal rhythmicity, ethanol was administered in the evening in amounts usually consumed during social ingestion to nine healthy volunteers in a double blind, cross-over study. Plasma concentrations of melatonin, catecholamines (norepinephrine and epinephrine), and ethanol were measured by RIA, high pressure liquid chromatography, and gas chromatography before and for 12 h after the administration of 0, 0.5, and 1 g ethanol/kg wt. Plasma melatonin and catecholamines displayed expected diurnal rhythms, with peak values at 0300-0400 h for melatonin and trough values at 0100-0400 h for catecholamines. Intake of ethanol between 1900-1945 h inhibited the nocturnal melatonin secretion dose-dependently during the first half of the night, with no changes in urinary excretion of melatonin. The inhibition was 41% (P < 0.05) from the control at midnight for both ethanol doses, 33% (P < 0.05) at 0100 h, and 18% (P < 0.05) at 0200 h for the higher dose. In addition, the higher dose of ethanol increased plasma norepinephrine levels at 2000 and 2200 h (P < 0.01) until 0400 h (P < 0.05). Taking into account the involvement of melatonin in the regulation of sleep and diurnal rhythms, we suggest that ethanol-induced suppression of nocturnal melatonin secretion and an increase in noradrenergic activity may be closely associated with disturbances in sleep and performance.

[Indexed for MEDLINE]

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