Melatonin may reduce self-harm in young people with anxiety and depression, suggests an observational study from Karolinska Institutet in Sweden. 

The study, published in The Journal of Child Psychology and Psychiatry, found the risk of self-harm increased in the months preceding melatonin prescription and decreased thereafter, especially in girls. 

Melatonin is the most commonly prescribed drug for sleep disturbances in children and adolescents in Sweden, according to a press release by Karolinska Institutet, which notes that melatonin use has dramatically increased in recent years. It has been available over the counter in Sweden since 2020.

“Given the established link between sleep problems, depression, and self-harm, we wanted to explore whether medical sleep treatment is associated with a lower rate of intentional self-harm in young people,” says Sarah Bergen, PhD, docent at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet, who led the study, in a press release.

Psychiatric Disorders Were Common

The study identified over 25,500 children and teenagers between the ages of 6 and 18 who were prescribed melatonin in Sweden. Over 87% had at least one psychiatric disorder, mainly attention-deficit hyperactivity disorder, anxiety disorders, depression, or autism spectrum disorder. Self-harm was about five times more common in girls than in boys.

The researchers estimated the risks of self-harm in the same individual while on or off medication by comparing the risk in the last unmedicated month with the 12 months after melatonin treatment was initiated. By doing so, they were able to take into account background factors that may affect associations, such as genetics, sleep disorder severity, or psychiatric disorders.

The risk of self-harm increased shortly before melatonin was prescribed and decreased by about half in the months following the initiation of treatment. Risk reduction was particularly evident among adolescent girls with depression and/or anxiety disorders.

Youth Mental Health Crisis

“There is currently a youth mental health crisis, and the risk of self-harm and suicide is high,” says Bergen in a press release. “Our findings support the hypothesis that sleep interventions may reduce self-harm in this population, especially in girls.”

As it was an observational study, it cannot establish a causal relationship between melatonin and reduced self-harm rates. To check whether the use of other medications might have affected the findings, analyses were also carried out which excluded antidepressant users. The results were similar.

“This suggests that melatonin might be responsible for the reduced self-harm rates, but we cannot rule out that the use of other psychiatric medications or psychotherapy may have influenced the findings,” says Marica Leone, PhD, first author of the study, in a press release.

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