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

J Clin Endocrinol Metab. 1993 Sep;77(3):780-3. doi: 10.1210/jcem.77.3.8370699.


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.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Circadian Rhythm
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Epinephrine / blood
  • Ethanol / administration & dosage
  • Ethanol / blood
  • Ethanol / pharmacology*
  • Female
  • Humans
  • Kinetics
  • Male
  • Melatonin / blood
  • Melatonin / metabolism*
  • Norepinephrine / blood
  • Random Allocation


  • Ethanol
  • Melatonin
  • Norepinephrine
  • Epinephrine