BACKGROUND: Delayed cerebral ischemia (DCI) is a cause of morbidity associated with aneurysmal subarachnoid hemorrhage (aSAH). Neuroinflammation contributes to the development of DCI. Melatonin is a sleep-promoting hormone known to have cerebral anti-inflammatory properties. We hypothesized that synthetic melatonin (or the selective melatonin receptor agonist ramelteon) incidentally prescribed to improve sleep may lower the incidence of DCI among hospitalized aSAH patients. METHODS: Subjects with a Hunt and Hess Grade I-III were identified from a data registry involving all aSAH patients admitted to our hospital between January 2015 and September 1, 2018. A cohort of patients who received either melatonin or ramelteon during their hospitalization was compared to a matched cohort that did not receive these drugs. The primary endpoint was incidence of DCI. Secondary outcomes included modified Rankin score (mRS) at discharge, discharge destination, and mortality at 6 weeks from discharge. The two groups were compared using univariate analysis. P < 0.05 was considered significant. RESULTS: There was no significant difference in the incidence of DCI (15.8% vs. 16.9%, p = 1), discharge mRS (mRS 0-3: 51.3% vs. 45.1%, p = 0.59), discharge disposition (Home: 43.6% vs. 44.4, p = 0.47), or mortality (0% vs. 9.2%; p = 0.074) between the melatonin/ramelteon and non-melatonin groups. CONCLUSION: The use melatonin had no effect on DCI but may improve mortality in aSAH subjects. Prospective studies using a larger cohort are warranted to validate these findings.