To Örebro University

Background: Sleep disorders in youth have been associated with increased risks of injury, including suicidal behavior. This study investigated whether melatonin, which is themost common medication for sleep disturbances in youth in Sweden, is associated with a decreased risk of injury.

Methods: This population-based cohort study included 25,575 youths who initiated melatonin treatment between ages 6 and 18. Poisson regression was used to estimate rate of injuries in the year prior to and following melatonin-treatment initiation. A within-individual design was used to estimate relative risks by comparing injury risk in the last unmedicated month with injury risks in the 12 months after medication initiation. Analyses were stratified by sex, in-jury type, psychiatric comorbidities, and age at melatonin-treatment initiation.

Results: While body injuries, falls, and transport accident rates were comparable in the year before and after melatonin-treatment initiation, the risk of self-injurious behavior was highest in the months immediately prior medication and decreased thereafter. This was particularly prominent among adolescents with depression and/or anxiety, with females displaying greater absolute risks than males. Compared to the last unmedicated month, the 12 months post medication initiation had decreased relative risks for self-harm, with an IRR [95% CI] in the month following melatonin-treatment initiation of 0.46 [0.27-0.76] among adolescent females with psychiatric disorders, after excluding antidepressant users.

Discussion: Decreased risk of intentional injury was observed following melatonin-treatment initiation among females with depression and anxiety, suggesting that sleep interventions could be considered in an effort to reduce risk of self-injurious behavior in this population.