A high percentage of subjects diagnosed with alcohol use disorder (AUD) suffer from sleeping difficulties. Lack of sleep could lead AUD patients to relapse or, sometimes, to suicide. Most of the currently prescribed medications to treat this complex problem retain a high risk of side effects and/or dependence. Therefore, the aim of the current clinical trial is to investigate the possibility of the use of a safer treatment, such as the natural health product melatonin, to treat alcohol-related sleeping problems. Sixty treatment-seeking AUD subjects were assigned to melatonin (5 mg) or placebo for 4 weeks of treatment. Change in sleeping quality which is the primary outcome of the study was assessed using the Pittsburgh sleep quality index (PSQI) scale. Linear mixed models were used to statistically analyze the difference in scores before and after 4 weeks of treatment. There was a reduction in the global PSQI score in both groups with no significant drug effect between groups. In conclusion, the use of melatonin (5 mg)/day didn’t differ from placebo in decreasing sleeping problems in a sample of AUD subjects after 4 weeks of treatment. However, higher doses are worth exploring in future research.