The Truth About the Risks of Melatonin for College Students

Last updated September 3, 2026 · By Dave Knoepfle

If you searched for the risks of melatonin, here is the honest answer. Across 79 studies and 3,861 participants, researchers found no detectable increase in serious adverse events. The alarming headline you may have seen in November 2025 came from a preliminary abstract with real limitations. Melatonin is not the danger the coverage implied.

The actual problem is different, and almost nobody explains it. Melatonin is a timing signal, not a sedative, and it does very little for a college student’s sleep. Students take an average of 5mg, several times what the body makes on its own, and 98% take it within an hour of getting into bed. They are using a clock drug as a sleeping pill, at the wrong dose, at the wrong hour, for a problem it was never built to solve.

What the research actually says about melatonin risks

Start with what is documented, because it is less dramatic than the search results suggest.

A systematic review of 79 studies covering 3,861 participants found no detectable increase in serious adverse events for melatonin compared with placebo, and no meaningful difference in people withdrawing from trials because of side effects.

What the same review did find is a clear ranking of what people actually report.

Daytime sleepiness tops the list, at more than twice the rate of anything else. Which is worth sitting with, because daytime sleepiness is the problem most students are taking melatonin to solve. Mayo Clinic advises against driving or operating machinery for roughly five hours after a dose.

One finding in that review deserves more attention than it gets: 37% of the studies made no mention of adverse events at all. Not that there were none — that nobody reported. For a product sold in every pharmacy in the country, the safety literature is thinner than its reputation implies.

About that heart failure headline

On November 3, 2025, the American Heart Association published a news release on Abstract MP2306, presented at its Scientific Sessions 2025. It reported that among adults with insomnia, long-term melatonin users had roughly a 90% higher chance of a heart failure diagnosis over five years (4.6% versus 2.7%), were nearly 3.5 times as likely to be hospitalized for it, and were nearly twice as likely to die from any cause.

Those numbers are alarming, the coverage was extensive, and search interest in melatonin risks spiked to its highest point of the year that same week.

Here is what most of the coverage left out: the average participant was 55.7 years old and every one of the 130,828 people in the study had been diagnosed with chronic insomnia. Those in the melatonin group had been on it for at least a year, in many cases by prescription, since the database spans countries where melatonin requires one. This is not a study of nineteen-year-olds taking a gummy before an exam.

The AHA states plainly that the abstract was not peer reviewed and that the findings are preliminary until published as a full manuscript. The limitations it lists are substantial:

• Chronic insomnia is itself linked to cardiovascular problems. The people taking melatonin and the people at elevated cardiac risk were the same people, for reasons that may have nothing to do with the supplement.
• US over-the-counter users landed in the wrong group. Melatonin use was identified from medication records, so anyone buying it off a shelf in the US would have been counted as a non-user. The comparison group almost certainly contains melatonin users.
• No data on dose, on insomnia severity, or on psychiatric conditions.

The study’s own author was careful about it: “while the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship.” And more directly:

“The takeaway isn’t that melatonin is ‘bad’ or that everyone should stop taking it. It’s that we shouldn’t assume something is risk-free just because it’s natural or sold over the counter.”

Dr. Ekenedilichukwu Nnadi, study author, to The Washington Post

One more thing from that release is worth carrying forward, because it comes from an AHA expert rather than from us. Marie-Pierre St-Onge of Columbia, who chaired the AHA’s 2025 scientific statement on sleep health and was not involved in the study, noted that in the US melatonin “is not indicated for the treatment of insomnia” and that “people should be aware that it should not be taken chronically without a proper indication.”

The thing that actually matters: melatonin is a clock, not a sedative

Here is what most students believe melatonin does: makes you sleepy. Here is what it actually does: tells your body it is night.

It is the chemical signal your brain already produces as darkness falls. It does not sedate. It shifts sleep timing. That explains why it has such a small impact on sleep. Pooled across 19 randomized placebo-controlled trials and 1,683 subjects, melatonin reduced the time it takes to fall asleep by just 7.06 minutes (95% CI 4.37–9.75) and increased total sleep time by a measly 8.25 minutes.

A student expecting sedation and better sleep from a timing signal is expecting something melatonin does not do.

The four problems students have when taking melatonin

Researchers surveyed 331 US undergraduates and asked ongoing melatonin users exactly how they take it. The answers are consistent, and consistently off.

1. They take it expecting it to work. This is the first problem and it makes the other three possible. Across 19 randomized placebo-controlled trials, melatonin reduced time to fall asleep by seven minutes. A student swallowing a capsule and waiting to feel sleepy is waiting for something that is not coming, and most have no idea that is the whole documented return.

2. The dose is far too high. Students averaged 5.1mg. The amount the body produces naturally is a small fraction of that. Since melatonin is a signal rather than a sedative, a larger dose does not produce more sleep — it mainly produces more side effects, which is exactly what the dose-response data shows.

3. The timing shows what they think it is. Asked when they take it:

98% take it within an hour of bed. That is how you take a sedative — swallow it, lie down, wait to feel drowsy. It is not how anyone would take a signal meant to shift a biological clock. The timing is not a technique problem. It is evidence of what students believe they are taking.

4. They take it every night, which even the industry advises against. This is the part that should be better known. The Council for Responsible Nutrition — the trade body representing supplement manufacturers — states plainly that “melatonin supplements are not intended to treat chronic insomnia or other sleep disorders,” and its 2024 voluntary labeling guidelines recommend the advisory “for occasional and/or intermittent use only.”

Meanwhile, roughly 16% of college students report taking melatonin as part of a regular nightly routine.

And you may not know what you took. Researchers analyzed 31 commercial melatonin supplements across 16 brands by liquid chromatography. Actual content ranged from 83% below to 478% above what the label claimed, and more than 71% of products fell outside a 10% margin of their own label.

That is a 34-fold spread between the least and the most a single labelled dose could contain. Dose-dependent side effects are hard to avoid when the dose is unknown — and a student who feels nothing one week and wrecked the next may simply have opened a different bottle.

The grogginess may be coming from the pill

Put those pieces together and something uncomfortable follows.

A student is tired in the mornings. They take melatonin to fix it. They take several times the physiological dose, an hour before bed, from a bottle whose real content is uncertain. Next-day drowsiness is the best-documented side effect and it gets worse with dose.

The thing they are taking to fix tired mornings may be contributing to tired mornings. And because the pill is framed as the solution, it is the last thing they suspect.

Why students reach for it, and what to do instead

None of this is a criticism of the students taking it. College is built against sleeping well. The dorm runs warm on heat nobody in the building controls. The roommate is on a different schedule. The dining hall closed at eight, so dinner is at eleven. Classes start at a different time every day, so there is no fixed wake time to anchor to. A student did not choose any of that.

And nobody taught them what to do about it. In the largest study to ask, roughly three in four students said their school had never given them any information about sleep at all. So when a student cannot sleep, they do the only thing available: they buy the product they have seen advertised, sitting on a shelf at Target, promising exactly what they want. That is a completely reasonable response to a problem nobody prepared them for.

The problem is that melatonin solves a different problem than the one students have.

Melatonin treats a student’s sleep problem as a chemistry problem. Mostly it is not. Here is what is actually costing them sleep, and none of it is fixed by a capsule:

• Caffeine from a five o’clock drink, still circulating at midnight.
• Alcohol, which takes apart the second half of the night.
• The room itself — set to a temperature chosen for daytime occupancy, and in many buildings the student cannot adjust it at all.
• The weekend — a wake time that swings three hours on Saturday and costs them Monday.
• The body clock — which does respond to something, just not to a supplement. Light is the dominant signal setting circadian timing and it is far more powerful than a pill. Sleep Hack 16 covers what melatonin actually does and what to use instead; Sleep Hack 14 covers the input that does the work.

Every one of those has an answer. None of the answers is a capsule, and none of them costs anything to act on once you know it. That is why we created our College Sleep Hacks™, a new online sleep program that helps students learn how to overcome the challenges of sleep at school — dorms, roommates, late meals, irregular schedules, caffeine and much, much more. $99 buys the entire program that the student keeps for life.

Frequently asked questions

What are the risks of melatonin?
For healthy adults taking it occasionally at low doses, the documented risks are modest. A systematic review of 79 studies and 3,861 participants found no detectable increase in serious adverse events. What is well documented is dose-dependent next-day impairment: doses of 10mg or more significantly increased drowsiness, headache and dizziness compared with placebo. Mayo Clinic advises against driving or operating machinery for roughly five hours after a dose. Worth knowing: 37% of the studies in that review did not report on adverse events at all, so the safety literature is thinner than the category's reputation suggests.

Is melatonin bad for your heart?
On November 3, 2025 the American Heart Association reported on a preliminary study finding that among adults with insomnia, long-term melatonin users had a roughly 90% higher chance of heart failure diagnosis over five years. The finding got wide coverage. What most coverage left out: the average participant was 55.7 years old, every one had chronic insomnia — itself linked to cardiovascular problems — the abstract was not peer reviewed, and US over-the-counter users would have been counted in the non-melatonin comparison group. As the study’s author said, the takeaway is not that melatonin is bad, but that we should not assume something is risk-free because it is sold over the counter.

Why do I feel groggy the morning after taking melatonin?
Usually dose or timing. Melatonin's side effects are dose-dependent, and next-day drowsiness becomes significantly more common at higher doses. College students average about 5mg per dose, which is several times what the body produces on its own. If a student is taking melatonin to fix tired mornings and waking up groggy, some of that grogginess may be coming from the supplement.

How much melatonin should a college student take?
That is a question for a doctor, not a blog. What the research shows is that more is not better: melatonin is a timing signal rather than a sedative, and a larger dose does not produce more sleep. The supplement industry's own 2024 labeling guidelines recommend upper dose limits and advise 'for occasional and/or intermittent use only.'

Is it safe to take melatonin every night?
The trade body representing supplement manufacturers advises against it. The Council for Responsible Nutrition states that melatonin supplements are not intended to treat chronic insomnia or other sleep disorders, and its voluntary labeling guidelines recommend the advisory 'for occasional and/or intermittent use only.' Roughly 16% of college students report taking melatonin as part of a regular nightly routine.

Does melatonin actually work?
It reduced time to fall asleep by about seven minutes across 19 randomized placebo-controlled trials and 1,683 subjects, and increased total sleep time by about eight minutes. The authors noted those effects are smaller than prescription sleep medications produce. Melatonin is a timing signal rather than a sedative, so students expecting it to make them sleepy are expecting something it does not do.

Related reading:

• Do Sleep Supplements Work for College Students? — melatonin, magnesium and the rest of the shelf
• Online College Sleep Programs vs. Sleep Supplements — the effect sizes side by side

Sources:

• Ferracioli-Oda, E., Qawasmi, A. & Bloch, M.H. (2013). “Meta-analysis: melatonin for the treatment of primary sleep disorders.” PLOS One, 8(5), e63773. (19 studies, 1,683 subjects)
• Peltz, J.S. & Rogge, R.D. (2023). “Unintended consequences: college students’ melatonin usage, sleep disturbance, and depressive symptoms.” Sleep and Biological Rhythms. (n=331 US undergraduates)
• Erland, L.A.E. & Saxena, P.K. (2017). “Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content.” Journal of Clinical Sleep Medicine, 13(2), 275–281.
• Besag, F.M.C., et al. (2019). “Adverse events associated with melatonin for the treatment of primary or secondary sleep disorders: a systematic review.” CNS Drugs, 33(12), 1167–1186. (79 studies, 3,861 participants)
• American Heart Association. “Long-term use of melatonin supplements to support sleep may have negative health effects.” Scientific Sessions 2025, Abstract MP2306, published November 3, 2025 (n=130,828; not peer reviewed); Council for Responsible Nutrition statement, November 3, 2025; reporting in The Washington Post, November 3, 2025.
• Council for Responsible Nutrition, Recommended Guidelines for the Labeling, Formulation and Packaging of Melatonin-Containing Dietary Supplements (2024).
• Bacaro, V., et al. (2024). “A comprehensive assessment of bedtime routines and strategies to aid sleep onset in college students.” Clocks & Sleep, 6(3).