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Can Melatonin Cause Heart Problems? What the 2025 Research Reveals

A new wave of headlines claims that melatonin — the “natural” sleep aid millions rely on nightly — could raise your risk of heart failure by nearly 90%. That sounds alarming. But is it true?

This study kicked off a massive conversation about melatonin and heart health, and whether long-term use is as harmless as most people assume.

Let’s unpack what this research actually found, where the science stands, and what safer, smarter alternatives exist for better sleep and heart health.

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What the 2025 Study Found

Researchers analyzed electronic health records from more than 130,000 U.S. adults diagnosed with insomnia who used melatonin regularly for at least one year.
Over a five-year period, melatonin users were found to have a 90% higher risk of developing heart failure — or being hospitalized or dying from it — compared to non-users.

The findings were presented at the American Heart Association (AHA) Scientific Sessions 2025.
That alone is enough to generate massive attention, and understandably so. Melatonin is one of the most popular supplements in America, with usage up over 400% since 2010.

But headlines love shock value — and this one leaves out some critical context.

Correlation Is Not Causation

The first and biggest caveat:
This was an observational study. That means researchers tracked outcomes based on existing data — not through a controlled experiment.

So while the numbers show a correlation between melatonin use and heart failure risk, they don’t prove melatonin caused the problem.

Here’s why that matters:

  • Many melatonin users already struggle with insomnia, anxiety, obesity, or metabolic issues — all of which can independently raise cardiovascular risk.
  • The data came primarily from prescription records, but in the U.S., melatonin is almost always purchased over the counter. That means many self-medicating users weren’t even included or were misclassified.
  • Researchers had no information about dosage, brand quality, purity, or duration of use — all critical details that can dramatically alter effects.

In short, the data are concerning, but incomplete.

Melatonin’s Mixed Record in Heart Research

Melatonin isn’t new to cardiovascular science.
It’s a hormone produced naturally by the pineal gland that helps regulate circadian rhythm — your body’s internal clock.
Beyond sleep, it influences blood pressure, oxidative stress, and even cardiac rhythm.

That’s why the research is so confusing.

  • Some studies suggest melatonin may protect the heart by reducing nighttime blood pressure and scavenging free radicals.
  • Others indicate that long-term, high-dose melatonin can disrupt normal cortisol cycles, interfere with the body’s natural hormonal balance, and alter autonomic control of heart rate.

A 2022 review in Frontiers in Physiology found that melatonin’s cardiovascular effects are dose-dependent and timing-dependent — meaning the difference between “helpful” and “harmful” may come down to how much, how often, and when you take it.

The new AHA data adds another layer to the debate: maybe melatonin isn’t as harmless as it seems when taken long term.

Why Melatonin Use Keeps Rising

The U.S. market for melatonin has exploded over the past decade, reaching an estimated $1.7 billion annually.
People turn to it for many reasons: jet lag, night-shift work, post-pandemic insomnia, or simply the desire for a “natural” fix that doesn’t require a prescription.

But “natural” isn’t the same as “risk-free.”
Melatonin supplements in the U.S. are poorly regulated, and independent lab tests have found actual melatonin content can vary by 80% or more from what’s listed on the label. Some even contain serotonin contamination, which can dangerously affect heart rhythm.

That means two people both taking “5 mg melatonin” could be consuming entirely different doses — and potentially getting very different biological effects.

How Melatonin Could Affect the Heart

So how might melatonin raise heart failure risk, if it truly does? Scientists are still investigating, but several mechanisms have been proposed:

  • Disruption of circadian blood pressure regulation — Melatonin influences nocturnal drops in blood pressure. Too much may blunt this healthy pattern.
  • Autonomic imbalance — Excess melatonin can interfere with sympathetic/parasympathetic signaling, potentially leading to arrhythmias in vulnerable people.
  • Hormonal interference — Long-term supplementation can desensitize melatonin receptors or alter cortisol rhythms, impacting heart workload.
  • Pro-oxidative paradox — At physiological levels, melatonin acts as an antioxidant. In excess, it may paradoxically promote oxidative stress in cardiac tissue.

None of these theories are proven — but they illustrate why more is not always better when it comes to hormonal supplements.

Dark medical scene with a heart model next to melatonin bottle under harsh spotlight

The Safer Sleep Alternatives — Backed by Science

If melatonin isn’t ideal for long-term use, what actually helps you sleep and supports cardiovascular health?

Here are five research-backed nutrients that can safely replace melatonin in most situations — and come with additional heart benefits.

1. Magnesium (especially glycinate or malate)

Magnesium supports over 300 enzymatic reactions in the body, including muscle relaxation and nerve balance.
Low magnesium levels are strongly associated with poor sleep quality and hypertension.

In studies, magnesium glycinate helps reduce nighttime awakenings and improve deep sleep — without hormonal interference.

For example, Life Extension Magnesium Caps and Vitalitown Magnesium Complex both use highly absorbable forms ideal for daily use.

2. Taurine

Taurine is an amino acid that supports heart rhythm stability, stress resilience, and sleep onset.
It increases GABA activity — the brain’s primary calming neurotransmitter — while lowering adrenaline levels.

Taurine has also been shown to reduce blood pressure and protect against oxidative stress in cardiac cells.
It’s a natural fit for anyone who wants both heart and sleep benefits in one capsule.

Brands such as NOW Foods Taurine 1000 mg are widely trusted and clinically tested for purity and consistency.

3. L-Theanine

Extracted from green tea, L-theanine promotes a calm, focused state without sedation.
Clinical trials show it reduces sleep latency (the time it takes to fall asleep) and enhances REM quality.
It’s especially effective when paired with magnesium or glycine.

Look for reputable options like Doctor’s Best L-Theanine or Life Extension L-Theanine that feature standardized dosages.

4. Glycine

This small amino acid lowers core body temperature and promotes restorative deep sleep.
In several studies, taking 3 grams before bed improved next-day alertness and reduced fatigue.
It also supports liver detox and collagen synthesis — two underrated factors in metabolic health.

NOW Foods Glycine 1000 mg capsules provide an easy, precise way to reach the studied dose.

5. CoQ10 (Ubiquinone or Ubiquinol)

While not a sleep aid per se, CoQ10 is a critical antioxidant for heart function, especially in older adults or anyone on statins.
Poor sleep and oxidative stress both deplete CoQ10, which can worsen fatigue and cardiovascular strain.

Supplementing helps restore mitochondrial energy production, potentially improving endurance and recovery.

Qunol Ultra CoQ10 100 mg is one of the most bioavailable forms on the market, used in numerous clinical trials.

Lifestyle Fixes That Make the Difference

Supplements can help, but they’re not magic on their own.
You can amplify results by combining them with small, strategic habit shifts:

  • Keep a consistent bedtime — your body thrives on rhythm.
  • Limit blue light two hours before bed.
  • Avoid alcohol and heavy meals close to bedtime.
  • Try a magnesium-taurine combo about an hour before sleep.
  • Use natural light exposure in the morning to reset your circadian rhythm.

Over time, these habits build a foundation for both deep sleep and a strong heart — without hormonal manipulation.

When to Be Cautious With Melatonin

If you still prefer melatonin for occasional use — for jet lag or night-shift recovery — keep these best practices in mind:

  • Use low doses (0.3–1 mg) rather than the common 5–10 mg tablets.
  • Avoid nightly use for more than 2–3 weeks at a time.
  • Buy from verified, third-party-tested brands to ensure purity.
  • Consult your doctor if you have heart disease, arrhythmias, or take medications affecting blood pressure or serotonin.

For most people, melatonin should be a temporary tool, not a long-term sleep strategy.

The Bottom Line

The new 2025 study linking melatonin to higher heart failure risk deserves attention — but not panic.
It doesn’t prove causation, and it certainly doesn’t mean melatonin is instantly dangerous.
It does, however, serve as a clear reminder: supplements that alter hormones should be used thoughtfully and sparingly.

If you’re using melatonin every night, consider phasing toward nutrient-based alternatives like magnesium, taurine, or L-theanine.
They work with your body’s natural systems — not against them — and support both rest and resilience in the long run.

This content is for informational purposes only and is not intended as medical advice. Always consult with your healthcare provider before starting any new supplement or treatment.

For further reading: 7 Proven Sleep Supplements That Actually Work (Without Addiction)

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