Hi Reader,

Your inbox is probably full of alarming headlines about melatonin this week. Let's cut through the noise.

If you've seen the news about melatonin potentially increasing heart failure risk by 90%, you're likely wondering: Should I toss that bottle in my medicine cabinet? Was my doctor wrong to suggest it? And why does everyone online seem to have a different opinion?

Let's dig into what we actually know—and what you can do with that information.

The Study + Why I'm Taking It Seriously (Even If It's Not Definitive)

What they found: A preliminary 2025 study tracked 130,000+ adults with chronic insomnia over 5 years. Those using melatonin for ≥1 year had:

• 90% higher risk of heart failure diagnosis
• 72% higher hospitalization risk
• 35% higher all-cause mortality

Yes, it's observational (not proof of causation) and not yet peer-reviewed. Critics rightfully point out potential confounding—maybe sicker people with worse insomnia are more likely to take melatonin long-term.

But here's why I'm not dismissing it: The signal is plausible (melatonin affects cardiovascular function), the magnitude is significant, and it aligns with a pattern I see clinically that concerns me.

The tolerance trajectory I keep seeing:

• Month 1: Start with 1-3 mg, it helps a bit
• Month 3: Effect diminishes, increase to 5 mg
• Month 6: Now taking 10 mg, "not working like it used to"
• Year 2: Trying 15-20 mg

People end up taking higher doses for longer periods than the original research ever supported—and we have almost no long-term safety data for that use pattern.

Meanwhile, what melatonin actually does for sleep is modest:

• Reduces sleep onset by 7-10 minutes
• Increases total sleep by 8-15 minutes
• Works best for jet lag and circadian rhythm issues—not chronic insomnia

If you've been taking it nightly for 6+ months and still have sleep problems, the melatonin isn't solving your issue. You need to dig deeper into sleep hygiene, underlying disorders (sleep apnea?), or try CBT-I, which consistently outperforms melatonin.

Why Context Changes Everything

Here's where it gets nuanced: I'm skeptical of chronic melatonin for sleep, but I understand the appeal for serious disease.

The high-dose advocates aren't totally wrong about the science. At 10+ mg, melatonin shifts from circadian signaling to receptor-independent effects: direct antioxidant activity, mitochondrial protection, anti-inflammatory cascades. And there's genuinely interesting data for:

• Parkinson's: Motor improvements with 10-30 mg in meta-analyses
• Cancer: 20-40 mg alongside chemo reduces side effects, may improve survival
• ALS: Meaningful delays in animal models, ongoing human trials at 50-100 mg

The critical difference in risk-benefit calculation:

If you're facing progressive neurodegeneration or fighting cancer, a potential 90% increased heart failure risk in 30 years looks very different than if you're 35 and taking it for sleep. You're already managing complex treatments with significant risks. Quality of life improvements may be worth it.

But even then: This should be a conversation with your specialist (get multiple opinions), not based on internet forums. And we still don't have long-term safety data in any population.

What You Should Actually Do

If you're taking it for chronic insomnia:

❌ Probably time to reconsider, especially if:

• You've been on it 6+ months
• Your dose keeps creeping up
• You're over 65 or have cardiac risk factors

✅ Where it still makes sense:

• Short-term use (2-4 weeks) to reset sleep patterns
• Intermittent use for jet lag or shift work
• Specific circadian disorders

✅ Better alternatives to try for chronic insomnia:

• CBT-I (gold standard, more effective than melatonin)
• Sleep hygiene basics (consistent schedule, cool dark room, no screens 2 hours before bed)
• Rule out sleep apnea or other underlying disorders

If you're considering it for "anti-aging":

You're essentially self-experimenting based on rodent studies while we're seeing potential cardiovascular signals. Exercise and Mediterranean diet have exponentially more robust longevity data. If you proceed anyway, start low, track biomarkers closely, and have proper monitoring.

If you have Parkinson's, cancer, or ALS:

The calculation changes. Discuss with your specialist—this might be a reasonable risk-benefit trade-off for your situation. But get second opinions and monitor closely.

If you're over 65 with heart disease:

Be especially conservative. You're highest-risk for the 2025 preliminary findings. If you use it, keep it low-dose (≤3 mg), short-term, and discuss with your cardiologist.

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The Bottom Line (about melatonin):

Melatonin isn't universally dangerous, but it's also not the harmless supplement we've been treating it as.

Know your goal, assess your personal risk, try evidence-based alternatives first, and make an informed decision for your specific situation.

​

Hillary Lin, MD

Co-Founder & CEO

​Care Core​

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