Melatonin decreases delirium in elderly patients: a randomized, placebo-controlled trial

Int J Geriatr Psychiatry. 2011 Jul;26(7):687-94. doi: 10.1002/gps.2582. Epub 2010 Sep 15.


Background: Disturbance in the metabolism of tryptophan and tryptophan-derived compounds (e.g., melatonin) may have a role in the pathogenesis of delirium.

Objective: To evaluate the efficacy of low dose exogenous melatonin in decreasing delirium.

Design: A randomized, double-blinded, placebo-controlled study.

Setting: An Internal Medicine service in a tertiary care centre in London, Ontario, Canada.

Participants: 145 individuals aged 65 years or over admitted through the emergency department to a medical unit in a tertiary care hospital.

Intervention: Patients were randomized to receive either 0.5 mg of melatonin or placebo every night for 14 days or until discharge.

Measurements: The primary outcome was the occurrence of delirium as determined by Confusion Assessment Method (CAM) criteria.

Results: Of a total of 145 individuals (mean age (standard deviation): 84.5 (6.1) years) 72 were randomly assigned to the melatonin group and 73 to the placebo group. Melatonin was associated with a lower risk of delirium (12.0% vs. 31.0%, p = 0.014), with an odds ratio (OR), adjusted for dementia and co-morbidities of 0.19 (95% confidence intervals (CI): 0.06-0.62). Results were not different when patients with prevalent delirium were excluded.

Limitation: An intention to treat analysis was not possible due to loss to follow-up.

Conclusion: Exogenous low dose melatonin administered nightly to elderly patients admitted to acute care may represent a potential protective agent against delirium.

Publication types

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

MeSH terms

  • Acute Disease
  • Aged
  • Aged, 80 and over
  • Central Nervous System Depressants / administration & dosage*
  • Delirium / prevention & control*
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Melatonin / administration & dosage*
  • Ontario


  • Central Nervous System Depressants
  • Melatonin