 A critical precipitating and maintaining feature of delirium is disrupted sleep. Melatonin is a widely available natural health product with evidence in normalizing circadian rhythms and sleep. There is also preliminary evidence that melatonin can be used to prevent the development of delirium in hospitalized patients. We hypothesize that daily administration of melatonin 1.5mg in the evening, beginning at first admission to hospital and continuing for 14 days, will lead to decreased rates of delirium compared to placebo-treated comparison subjects. 