Melatonin has been sold to us as the ultimate harmless supplement for sleep. Science disagrees

Melatonin is widely sold as a harmless sleep aid, but evidence points to quality problems, limited benefits, and real safety risks.

Studies have found major gaps between labeled and actual doses, and some products have even contained serotonin.

Its sleep benefits appear mainly limited to circadian-rhythm issues like jet lag, while gummies have contributed to accidental overdoses in children.

The article also flags possible interactions with anticoagulants and contrasts looser U.S. supplement rules with stricter Spanish oversight for higher-dose products.