Melatonin in schizophrenic outpatients with insomnia: a double-blind, placebo-controlled study

Low nighttime levels of melatonin have been demonstrated in patients with insomnia, and melatonin has been shown to have hypnotic properties in some groups of such subjects. Low melatonin levels have also been observed in patients with schizophrenia; however, there is little literature on the efficacy of exogenous melatonin in treating insomnia associated with schizophrenia.

Stable DSM-IV schizophrenic outpatients (N = 40) with initial insomnia of at least 2 weeks' duration were randomly assigned to augment their current medications with either flexibly dosed melatonin (3-12 mg/night; N = 20) or placebo (N = 20). By use of a questionnaire, double-blind assessments of aspects of sleep functioning were obtained daily across the next 15 days. The study was conducted between March and December 2002.

The modal stable dose of melatonin was 3 mg. Relative to placebo, melatonin significantly improved the quality and depth of nighttime sleep, reduced the number of nighttime awakenings, and increased the duration of sleep without producing a morning hangover (p < .05). Subjectively, melatonin also significantly reduced sleep-onset latency, heightened freshness on awakening, improved mood, and improved daytime functioning (p < .05).

Melatonin may be a useful short-term hypnotic for schizophrenic patients with insomnia. Melatonin could be considered for patients in whom conventional hypnotic drug therapy or higher sedative antipsychotic drug doses may be problematic.