OBJECTIVE: To review clinical studies evaluating melatonin doses and their effects on sleep in adults 65 years of age and older. DATA SOURCES: The MEDLINE databases were searched (1946 to October 10, 2018) using the following Medical Subject Heading terms: melatonin and: sleep initiation and maintenance disorders, dyssomnia, sleep wake disorders, insomnia, sleep disorders intrinsic, and sleep disorders circadian rhythm. Sources were limited to English and human data. STUDY SELECTION/DATA EXTRACTION: An initial search resulted in 144 publications, with 25 included in this review. Studies were selected for full review based on design, mean age of participants, use of exogenous melatonin, and reports on any sleep-related outcome. DATA SYNTHESIS: Because of the side effect profiles of most prescription and nonprescription sleep aids, safe and effective alternative therapies are necessary. Based on the current literature, no dose-related response to sleep improvement has been identified for melatonin in older adults. Variations in melatonin formulation and dosages, as well as available tools to measure sleep outcomes, make it challenging to compare studies. CONCLUSIONS: This review evaluated a variety of melatonin doses, 0.5 mg to 10 mg, and their effects on sleep in older adults. The results varied, with some studies finding no difference in sleep outcomes when compared with placebo, while other studies found statistically significant improvements in sleep outcomes. Doses of melatonin between 1 mg and 6 mg appear to be effective for improving sleep in older adults; however, further studies are needed to find the optimal minimum effective dose.