A prescription-only hormone used to treat sleep disorders may increase the risk of heart failure if used long-term.
Researchers analysed five years of health records for more than 130,000 people with insomnia.
They found that those who used melatonin for a year or more had nearly twice the risk of developing heart failure, and of dying from any cause, Newstalk reported.
The study also found an increased risk of heart failure among people who had two or more melatonin prescriptions filled at least 90 days apart.