Melatonin improves sleep quality of patients with chronic schizophrenia

Background: Accumulating evidence indicates decreased melatonin levels in p atients with schizophrenia. Insomnia, mainly difficulty in falling asleep a t night, is commonly reported in this population. Association of insomnia w ith low or abnormal melatonin rhythms has been repeatedly documented. Melat onin is an endogenous sleep promoter in humans. We hypothesized that insomn ia in patients with schizophrenia may be partially due to diminished melato nin output. In this study, we measured melatonin output in patients with ch ronic schizophrenia and assessed the effects of melatonin replacement on th eir sleep quality. Method: In a randomized, double-blind, crossover, clinically based trial, 1 9 patients with DSM-IV schizophrenia who were treated with the normal treat ment regimen were given melatonin (2 mg, controlled release) or placebo for 2 treatment periods of 3 weeks each with 1 week washout between treatment periods (7 weeks total). For measuring endogenous melatonin production, uri ne was collected from each patient every 3 hours between 9:00 p.m. and 9:00 a.m. Actigraphy was performed for 3 consecutive nights at the end of each period. Activity- and rest-derived sleep parameters were compared for the w hole population with treatment arm as the intervening variable. A separate analysis was performed for patients subgrouped into high versus low sleep e fficiency. Results: All patients had low melatonin output. Melatonin replacement signi ficantly improved rest-derived sleep efficiency compared with placebo (83.5 % vs. 78.2%, p = .038) in this population. Improvement of sleep efficiency was significantly greater (p < .0014) in low-efficiency (80% vs. 67%) than high-efficiency sleepers (88% vs. 90%). In addition, during melatonin thera py, tendencies toward shortened sleep latency (by 40 minutes, p < .056) and increased sleep duration (by 45 minutes, p < .078) were observed in low- b ut not high-efficiency sleepers. Conclusion: Melatonin improves sleep efficiency in patients with schizophre nia whose sleep quality is low.