The (Possible) Lurking Dangers of Melatonin

By: David Ostrowsky

Many Americans have long viewed melatonin as a harmless supplement that’s readily accessible on the shelf at the local grocers or CVS. Certainly, millions consider melatonin to be an effective sleep aid with minimal side effects and no long-term deleterious effects. However, as of this past November, results from a new study may suggest otherwise. In early November, disturbing headlines streamed through the internet, highlighting new research findings that concluded melatonin usage can be linked to a 90 percent increase in heart failure. The headlines summarizing the study’s results served as prime click bait as the potential dangers gave many users a post-Halloween scare.

A quick recap of the unpublished study that was later presented at an American Heart Association conference: Researchers evaluated global health records from over 130,000 adults battling insomnia, who were sorted into two groups. One included participants who took melatonin supplements for at least one year; the other was comprised of those who had no record of consumption.

The research team then measured the participants’ risk of heart failure, which is when the heart can’t pump sufficient blood to provide the body’s organs with oxygen, over five years. The results were rather sobering. The risk of heart failure was 4.6 percent for those taking melatonin, whereas it was merely 2.7 percent for those who had no record of taking the supplement. In more layperson terms, those who took melatonin, the study suggested, had a 90 percent higher risk of experiencing heart failure while they were also more than 3.5 times susceptible to being hospitalized for heart failure and were twice as likely to die of any cause.

While undoubtedly shocking, the findings were swiftly put into context by many sleep experts, who believed it was premature to draw conclusions from a study that had considerable limitations and also happened to not be peer-reviewed. For one, the group taking melatonin only consisted of those with documented melatonin prescriptions. This is a very critical dynamic because in several European countries, including England, a prescription is needed to purchase melatonin. However, in the US, a prescription is, of course, unnecessary, meaning that some American participants in the non-melatonin group may have actually been taking melatonin (it just wasn’t in their official medical records, because it was never prescribed.) Secondly, according to Dr. Phyllis Zee, a sleep doctor and researcher at Northwestern Medicine who was actually not involved with the study, there was a dearth of information about melatonin dosage and insomnia severity, both factors that could impact the risk of heart disease. Dr. Akinbolaji Akingbola, an esteemed sleep medicine physician at the University of Minnesota, who was also not involved in the study, posited that to truly gauge whether melatonin intake correlates with heightened risk of heart failure, researchers would have to conduct randomized controlled trials assigning people to consume either melatonin supplements or placebos.

All this is to say, there may not have been adequate proof of causation to demonstrate the data corroborates the downright alarming headlines.

“The study has too many limitations to determine whether melatonin increases the risk of heart failure—or even affects the heart at all,” health reporter Caroline Hopkins Legaspi wrote in a November 5 New York Times article.

Though the study has yielded more questions than answers—a segment of the medical community was left wondering if there needs to be further research conducted into whether insomnia or sleep apnea is the true culprit—it does serve as an important reminder that there is relatively little known about the safety of many supplements that we consume and give to children. As for melatonin, even though the wildly popular sleep-inducing supplement may mimic a hormone the body produces naturally, there evidently could still be underlying health risks. Which is why many medical professionals espouse cognitive behavioral therapy for insomnia in addition to establishing healthy sleep routines and avoiding caffeine and alcohol before bed. But lest we forget, for many Americans, particularly those of lower income status who have to get up early for physically taxing jobs that require constant hypervigilance (i.e., operating machinery), who need to fall asleep rapidly, such options aren’t feasible. Melatonin—even with its potential for triggering long-term cardiac issues—remains the most viable option for getting through the day.