Melatonin supplements, widely marketed in the United States and other nations as an effortless solution for sleepless nights, are increasingly viewed with caution by health experts. Though often sold in pharmacies and supermarkets — including child-friendly gummy versions — specialists warn that this seemingly “natural” remedy may conceal risks.
Recent headlines followed research presented at a major American cardiology conference, where investigators suggested a possible association between prolonged melatonin use and higher rates of heart failure and overall mortality. While the findings do not confirm causation, the authors described their data as a potential warning sign.
Heart Failure Signal Sparks Debate
The study, undertaken by researchers in New York and shared at a scientific meeting of the American Heart Association, observed more than 130,000 adults diagnosed with chronic insomnia over a five-year span. Participants who had consumed melatonin for at least one year appeared to face:
An estimated 90% higher likelihood of being diagnosed with heart failure
A roughly 3.5-fold increase in hospitalisation due to heart failure
Nearly double the overall mortality rate compared with those who did not use the hormone
However, experts stress that conference presentations are not yet subject to formal peer review. Consequently, the results are considered preliminary until vetted and published in a scientific journal.
Critics also note that since melatonin can be bought freely in many countries, some individuals classified as non-users may have taken the hormone without their intake being recorded — a factor that complicates comparisons.
What Melatonin Really Does
Despite its popularity as a “sleep hormone”, melatonin is technically a signal of darkness, not a sedative. Produced in the brain’s pineal gland, its levels rise as night approaches, helping to regulate the body’s internal clock.
Exposure to daylight — or artificial blue light from smartphone screens — suppresses this hormone, which explains why many people with irregular schedules or screen-heavy habits turn to manufactured melatonin. Its synthetic version is chemically identical to the naturally produced hormone and has been shown in controlled studies to assist with short-term sleep disruption, such as jet lag.
What alarms clinicians is not the occasional dose but its routine, long-term use, particularly at concentrations that far exceed physiological levels.
Experts Question Safety and Oversight
In the US, melatonin has become one of the most frequently purchased supplements, often in doses dramatically higher than what the human body produces. Unlike prescribed medicines, supplements are not tightly regulated there, and ingredient consistency between products can vary.
The study’s lead author, Dr Ekenedilichukwu Nnadi from SUNY Downstate Medical Center, stated that while melatonin is widely perceived as benign, their findings raise “serious safety concerns”.
Reported side-effects include headaches, fatigue, sudden sleep episodes, mood changes and irritability. Sleep researcher Marie-Pierre St-Onge of Columbia University expressed surprise at how readily the hormone is recommended, noting that in the US it is not officially approved for treating insomnia, despite its widespread use.
Rising Alarm Over Use in Children
Clinicians are most troubled by its increasing consumption among children. Social media trends praising melatonin-based sweets have contributed to soaring sales of child-targeted gummies in the US — some of which contain up to 3 milligrams per serving, significantly above natural physiological levels.
American health authorities have reported steep rises in accidental melatonin poisoning among youngsters. Paediatricians in Germany report parallel concerns, including cases of dizziness and overdose.
Another risk relates to dependency: long-term supplementation may suppress the body’s own hormone production, potentially worsening natural sleep regulation.
Simple Sleep Habits May Be Better Than Pills
Researchers emphasise that the body’s sleep cycle is a finely balanced system. Frequent disruption — whether through artificial light or hormone manipulation — may carry consequences beyond one restless night.
Until long-term impacts are scientifically clarified, specialists argue that melatonin should be approached as a hormonal intervention, not merely a harmless sleep aid. Particularly for children, routine bedtime rituals — such as darkness, reduced screen exposure and calming routines — are recommended over chemical alternatives.
As clinicians in Europe and the US continue to question melatonin’s expanding use, the emerging research has prompted a re-evaluation: sleep, they suggest, is a biological process best supported naturally whenever possible.