For many people, especially as they get older, sleep can become frustratingly unpredictable.
You may fall asleep easily but wake at 2 a.m. You may lie awake thinking about tomorrow. Or you may find yourself reaching for the same bottle of melatonin night after night because it feels like the simplest answer.
Melatonin has an appealing reputation. It is a hormone naturally produced by the body and is widely sold as a sleep supplement in many countries.
But a large study presented at the American Heart Association Scientific Sessions in 2025 suddenly put long-term melatonin use under a brighter spotlight.
Researchers examined electronic health records from 130,828 adults diagnosed with insomnia. Those whose records indicated melatonin use for at least a year had higher rates of heart failure, heart-failure hospitalization and death during five years of follow-up.
At first glance, those numbers sound alarming.
But there is a crucial catch: the study does not prove that melatonin caused those outcomes.
And newer evidence makes the picture even more complicated.
What Did the Big Study Actually Find?
The researchers used data from the TriNetX Global Research Network and compared 65,414 people with documented long-term melatonin use with a matched group who did not have melatonin recorded in their medical records.
The groups were matched across numerous characteristics, including age, sex, health conditions, medications, blood pressure and body mass index.
Over five years, heart failure was diagnosed in about 4.6% of the melatonin group compared with 2.7% of the comparison group. That corresponded to a hazard ratio of about 1.89.
Heart-failure hospitalization and death from any cause were also more common among people in the melatonin group.
Those are important findings.
But there is another important sentence in the study’s own description: the research cannot establish cause and effect.
The AHA specifically described the findings as preliminary because they were presented as a conference abstract and had not undergone full peer review at the time.
That distinction is easy to lose when a large number of patients and dramatic percentages appear in a headline.
Could Something Else Explain the Difference?
Possibly.
People taking melatonin for a year or longer are not necessarily comparable to people who sleep normally without it.
They may have more persistent insomnia. They may have depression or anxiety. They may have other health problems affecting sleep. They may use healthcare services more frequently.
The researchers themselves acknowledged that their database lacked important information about the severity of insomnia and some psychiatric conditions.
This is known as confounding.
Imagine two people taking the same supplement. One sleeps reasonably well and occasionally uses a sleep aid. The other has struggled with severe sleep problems for years.
If the second person develops heart disease more often, the supplement might be responsible—but the underlying health differences could also help explain the result.
That is why observational studies are valuable for identifying signals but usually cannot settle questions of causation by themselves.
A 2026 Study Added Another Piece to the Puzzle
The melatonin story did not end with the AHA findings.
In May 2026, researchers published an analysis using nationally representative NHANES data covering U.S. adults from 1999 through 2018.
They found that melatonin users differed from non-users in several important ways, particularly in sleep disturbance and depression.
After statistical adjustment, recent melatonin use was not significantly associated with prevalent cardiovascular disease or heart failure.
The authors described their findings as a contextual counterpoint to the earlier warning rather than proof that melatonin is either safe or dangerous.
So where does that leave us?
Some observational evidence raises a cardiovascular safety signal.
Other observational evidence does not confirm it.
Neither proves that long-term melatonin is harmful—or that it is completely harmless.
Why Older Adults Deserve Extra Attention
Sleep problems become particularly important later in life.
The National Institute on Aging notes that insomnia is the most common sleep problem among adults aged 60 and older. Medical conditions, medications, changes in routine and other sleep disorders can all contribute.
That means repeatedly treating the symptom without asking why sleep has changed may miss something important.
For example, persistent nighttime waking can have many possible causes. Sleep apnea, restless legs syndrome, pain, medication effects, mood disorders and other medical problems can interfere with sleep.
Sometimes the most useful question isn’t, “Which sleep supplement should I take?”
It is:
“Why am I sleeping badly in the first place?”
Melatonin Isn’t Simply a Harmless “Natural” Product
Melatonin is naturally produced by the brain’s pineal gland and helps regulate the sleep-wake cycle.
But the fact that a substance exists naturally in the body does not automatically make every supplemental dose appropriate for every person.
The amount, formulation, timing and individual circumstances matter.
And for older adults who take several prescription medications, adding any supplement deserves attention because of the possibility of interactions or unwanted effects.
The current evidence does not justify telling everyone to stop melatonin. But it also does not justify assuming that taking it every night for years is risk-free.
What About Chronic Insomnia?
This may actually be the most important part of the story.
If sleep problems continue for months, repeatedly adding a supplement may distract from the underlying condition.
The American Academy of Sleep Medicine recommends cognitive behavioral therapy for insomnia, or CBT-I, as an effective treatment for chronic insomnia. Behavioral approaches can address the patterns and thoughts that keep insomnia going rather than simply attempting to induce sleep.
The National Institute on Aging likewise notes that cognitive behavioral therapy can help older adults with insomnia and cautions that sleep medicines can carry risks when used long term.
That makes a proper sleep evaluation particularly worthwhile when insomnia becomes persistent.
Don’t Panic—But Don’t Ignore Persistent Sleep Problems
If you currently use melatonin, the latest research is not a reason to panic.
It is also not evidence that melatonin should be considered a long-term heart-health treatment.
Instead, the findings are a reminder that chronic sleep problems deserve proper attention.
For older adults, that can mean discussing persistent insomnia, nighttime waking, snoring, daytime sleepiness, medication changes or other sleep symptoms with a healthcare professional.
And if you have been taking melatonin regularly for a long time, mention it during medication reviews—even if you bought it without a prescription.
Your doctor or pharmacist can consider it alongside your other medicines and health conditions.
The Bigger Lesson
The most interesting finding from the 130,000-person study may ultimately be the question it raises rather than the answer it provides.
Melatonin has spent years occupying a comfortable space in the public imagination: natural, familiar and gentle.
But science is rarely that simple.
The 2025 study raised a cardiovascular warning. The 2026 NHANES analysis offered a different perspective. Together, they show why researchers need better long-term studies before declaring melatonin either dangerous or completely safe.
For now, perhaps the most sensible approach is neither fear nor blind reassurance.
If your nights have become a struggle, don’t simply ask what you can take to make yourself sleep.
Ask what your body might be trying to tell you.
Sometimes the real sleep solution begins not with another pill—but with finding the reason sleep disappeared in the first place.
Photo by Anna Shvets: https://www.pexels.com/photo/white-medicine-capsule-in-close-up-photography-3683091/