- A new study links long-term melatonin use to higher heart failure risk and death risk.
- The study is preliminary and doesn’t prove melatonin caused these heart-related outcomes.
- Most users weren’t affected, but nightly long-term use may warrant medical guidance.
Melatonin is one of the most popular sleep aids, but new research suggests it may not be risk-free when taken long term.
A large analysis presented by the American Heart Association found that adults with insomnia who took melatonin supplements for at least a year had higher rates of heart failure, hospitalizations and death compared to those who didn’t use them. The study doesn’t show that melatonin caused these outcomes, but it raises concerns because the supplement is widely available over-the-counter and often used nightly without medical supervision.
Sleep problems—including insomnia—are common, and research shows there’s a relationship between sleep and heart health. People with poor sleep are more likely to develop heart problems and those with cardiovascular conditions often develop sleep issues as well. Because of this, many people in these groups may look to melatonin to help them sleep.
While melatonin is a hormone the body naturally produces to regulate sleep-wake cycles, it’s also widely available in a range of doses as a supplement. This study is one of the first large-scale efforts to look specifically at its long-term use and the risk of heart failure, hospitalization and death.
How Was This Study Conducted?
The researchers used electronic health records from TriNetX, a large international database of hospital and clinic data. They included more than 130,000 adults who had been diagnosed with insomnia. From that group, they compared people who had documented melatonin use for at least a year with people who also had insomnia but no record of using melatonin.
To help with the comparison, the researchers matched the two groups based on factors like age, sex, race/ethnicity, heart and nervous system diseases, medications for those conditions, blood pressure and body mass index.
The study team then looked at up to five years of follow-up records to see who developed heart failure, was hospitalized for heart failure or died from any cause. Because melatonin is available over the counter in some countries, like the U.S., but not in others, the study could only include use that was documented in medical records.
What Did the Study Find?
The researchers found that people with insomnia who used melatonin for at least a year were more likely to develop heart failure, be hospitalized for heart failure or die from any cause compared to those who didn’t use melatonin.
About 4.6% of long-term melatonin users developed heart failure, compared to 2.7% of non-users. Hospitalizations for heart failure were also higher—19% in the melatonin group versus 6.6% in the comparison group. Death from any cause occurred in 7.8% of people using melatonin long term, compared to 4.3% of people who didn’t use it.
These differences remained even when the study team tightened the criteria and only included people who had at least two melatonin prescriptions spaced three months apart.
How Does This Apply to Real Life?
The overall risk for an individual remains relatively small. Over about five years, about five out of 100 people who used melatonin for at least a year developed heart failure, compared to about three out of 100 people who didn’t use it. Death from any cause occurred in roughly eight out of 100 long-term users versus about four out of 100 non-users. Hospitalizations for heart failure showed the biggest difference—about 19 out of 100 users compared to seven out of 100 non-users.
Most people who used melatonin long term did not experience these outcomes. Still, because melatonin is so widely used, even small increases in risk are worth paying attention to at a population level. This study is also a good reminder that it’s wise to check in with a healthcare provider before you start a new supplement. If you’re taking melatonin, consider asking a trusted healthcare professional about what dosage might make sense for you.
It’s also important to remember that this study shows a link, not proof that melatonin causes heart failure or death. It’s possible that people who use melatonin nightly for long periods may have more severe insomnia, untreated sleep apnea or other health conditions that affect both sleep and heart health. Those factors could help explain some of the differences seen in the study.
Our Expert Take
Because this study is still preliminary and not yet peer-reviewed, it shouldn’t be taken as proof that melatonin is harmful, but it does raise important questions. Key details like dosage and untreated sleep disorders weren’t fully accounted for, and those factors could help explain the results. More research is needed to understand whether the risk is related to melatonin itself or the health of the people who use it long-term.
In the meantime, melatonin may still be helpful for short-term or occasional sleep problems, but relying on it every night for months or years is something to discuss with a healthcare professional. Focusing on sleep hygiene and treating the underlying cause of insomnia is a safer long-term approach than depending on a supplement alone.
