New research into a popular sleeping aid has some scientists worried about long-term usage. An analysis of adults with insomnia, which has not yet been peer-reviewed, has found that people prescribed melatonin for more than a year are at greater risk of heart issues. Among more than 130,000 adults across multiple countries, those who were prescribed melatonin long-term had an 89 percent higher risk of heart failure over five years, and were twice as likely to die from any cause, compared with