Melatonin and Heart Health: Understanding the AHA Abstract Without the Alarm

There is no proven casual link between melatonin and heart failure.

By Dr. Travis Smith, DO – Bio Precision Aging Medical Editorial Team

A recent analysis presented at the American Heart Association (AHA) Scientific Sessions 2025 sparked headlines suggesting that long-term melatonin use may increase the risk of heart failure. But before we draw conclusions, it’s critical to understand what the study actually showed—and what it did not prove.

Let’s unpack the findings, the limitations, and what this means for anyone using melatonin to support sleep.

What the Study Found

Researchers analyzed electronic health-record data from over 130,000 adults with chronic insomnia in the TriNetX Global Research Network. They compared people who had at least 12 months of documented melatonin use with those who had no recorded use.

Over a roughly five-year follow-up, the data showed:

• Heart failure: 4.6 % of melatonin users vs. 2.7 % of non-users

• Hospitalizations: 19 % vs. 6.6 %

• All-cause mortality: 7.8 % vs. 4.3 %

  
  

At first glance, those numbers look concerning—but the AHA and study authors clearly stated: association does not equal causation.

Why These Results Don’t Prove That Melatonin Causes Heart Failure

issing and misleading exposure data

In the U.S., melatonin is sold over the counter. Most users never tell their doctor or have it entered into their chart. That means many so-called “non-users” probably took melatonin, which can distort the results.

Confounding by insomnia severity

Chronic, severe insomnia itself raises heart risk through increased sympathetic activity, blood-pressure swings, and inflammation. People who rely on melatonin long-term may represent this higher-risk insomnia group—making the supplement appear guilty by association.

Reverse causation

Early heart-failure symptoms—shortness of breath when lying down, restless sleep, nighttime awakenings—often lead people to start sleep aids. The heart issue may precede melatonin use rather than result from it.

Inconsistent supplement quality

A 2017 study found that 71 % of melatonin products deviated by more than 10 % from their labeled dose, and over a quarter contained serotonin contamination. When “melatonin” can mean many different doses and purities, it’s impossible to make firm biological conclusions.

EHR data limitations

Real-world datasets like TriNetX can miss medications, misclassify diagnoses, and introduce “immortal-time bias”—meaning participants had to survive long enough to be counted as long-term users.

What Controlled Trials Actually Show

Randomized clinical trials examining melatonin’s effects on blood pressure, oxidative stress, and metabolic health generally show neutral or mildly beneficial outcomes, not harm. Melatonin has antioxidant, endothelial, and circadian-regulating roles—none of which support the idea that it damages the heart.

What Clinicians (and Patients) Should Do

Treat the root cause: Chronic insomnia needs targeted care such as Cognitive Behavioral Therapy for Insomnia (CBT-I)—the gold-standard, evidence-based approach.

Screen for comorbidities: Sleep apnea, anxiety, depression, and metabolic disorders can all drive both insomnia and cardiac risk.

If using melatonin: Stick to short-term, purpose-specific use, and choose third-party-tested brands that verify dose accuracy and purity.

Document details: Clinicians should record formulation, dose, and duration in the medical record to improve future data quality.

The Bottom Line

This AHA analysis raises a hypothesis, not a verdict. It reminds us that data correlations must be tested through rigorous, randomized, event-powered trials before making clinical judgments.

Until such studies exist, patients and clinicians should contextualize—not catastrophize—these findings. When used appropriately, melatonin remains a valuable short-term tool for circadian rhythm support and sleep regulation.

References

American Heart Association (AHA 2025 Abstract); Laugsand LE et al., Eur Heart J 2014; Grossman E et al., J Hypertens 2011; Erland LAE & Saxena PK, J Clin Sleep Med 2017; Nassar M et al., TriNetX Review 2025

The information provided in this post is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Please consult with your healthcare provider before starting any new supplement regimen, exercise program, or making significant changes to your health routine, especially if you have existing medical conditions or take medications.