If they experience sleep disorders, many people turn to preparations that contain melatonin. However, this poses a considerable risk; a new study warns against long-term use of “natural” sleep hormones for heart health purposes.
It is considered a gentle aid for restless nights and an aid to falling asleep: melatonin, a “natural” sleep hormone that can be purchased at drug stores and pharmacies without a prescription. Millions of people regularly do this – in the good faith that they are doing something good for their bodies.
But a new study, presented in early November at the American Heart Association (AHA) annual meeting in New Orleans, now calls this certainty into question. Long-term use of melatonin harms the body and is associated with a higher risk of heart failure and death.
For the long-term study, researchers at SUNY Downstate Medical Center in New York analyzed the health data of more than 130,000 US patients over five years. All the participants suffered from insomnia, that is, chronic difficulty sleeping – although according to their medical records, only half had taken melatonin for at least a year.
The results of this study are worrying. It was found that people who took melatonin long-term had a 90 percent higher risk of heart failure than those who never used the hormone. The difference was even more pronounced when it came to hospitalization: 19 percent of melatonin users had to be treated for heart failure, compared with only six percent in the comparison group. And the death rate was almost twice as high, the researchers stressed.
Melatonin bad for the heart?
“Melatonin supplements may not be as harmful as is commonly believed,” said study leader Ekenedilichukwu Nnadi. “If our research is confirmed, this could impact how doctors advise their patients about sleep medications.” “It was surprising how clearly our data showed an association with serious heart problems,” continued Nnadi. While science is still cautious on this – a direct cause-and-effect relationship has yet to be proven – this research raises important questions about the safety of melatonin, especially with regard to unregulated products with concentrations sometimes ten times higher.
Unlike prescription medications, melatonin is not subject to a strict regulatory framework, so product quality and safety vary widely. Marie-Pierre St-Onge, a sleep doctor at Columbia University, expressed concern: “I am amazed that doctors even recommend melatonin for more than a year. In the United States, melatonin is not approved to treat insomnia – and should not be taken long term.”
It has long been known that lack of sleep causes disease. Cardiovascular disease, depression, obesity – many things are linked to lack of sleep. Modern people tend to self-medicate. Instead of rituals – no screen lights before bed, a regular daily rhythm, exercise in the fresh air – tablets are swallowed, drops are drunk and sprays are sprayed. Anyone who remembers the time when sleep was still considered a natural part of life, not an interfering factor in the daily grind, will feel: somewhere we went down the wrong path.
In the past, people looked for the cause, but now they are quick to take pills. Melatonin in particular offers a convenient solution for stressed people as a sleep aid: It’s a hormone that the body itself produces in the pineal gland, especially in the dark. This signals the organism: It is time to sleep. But what can be helpful in moderation, will be too much of a burden.
Melatonin side effects
This study also shows how difficult it is to obtain reliable data under such conditions. Because many people who take melatonin without a prescription don’t show up in any medical records. This means that the actual risk can still be underestimated.
There is also a warning from Germany: The Federal Institute for Risk Assessment (BfR) announced in 2024 that low doses of melatonin (from one milligram) can cause undesirable side effects in healthy adults such as drowsiness, headaches, reduced attention, unsteady gait and morning dizziness.
According to research, melatonin also affects blood sugar levels, which may influence the risk of type 2 diabetes, according to the BfR. There are also indications of possible interactions with certain drugs such as antihypertensive drugs and anticoagulants. Further investigation is needed, according to the agency.
US researchers also plan to conduct further research. The results are still preliminary – the AHA study has not yet been published in a specialist journal. However, heart failure affects more than 6.7 million adults in America alone and the number continues to rise. If over-the-counter sleeping pills only slightly increase this risk, this is a matter of social concern.
