Melatonin's Murky Role in Sleep and Cognition

Neurologist examines the potential benefits and risks of the popular sleep supplement

Apr. 6, 2026 at 1:56pm

Got story updates? Submit your updates here. ›

Neurologist Heidi Moawad reviews the latest research on using melatonin to improve sleep and potentially benefit cognitive health, but notes that the evidence is mixed - while animal studies suggest melatonin may have neuroprotective effects, human studies have shown only modest improvements in sleep and cognition, and some data even indicates potential cardiac risks with long-term use. Moawad advises physicians to carefully consider patients' melatonin use and to focus more on promoting healthy sleep hygiene practices.

Why it matters

Sleep deprivation is linked to a variety of chronic diseases, and sleep disorders can even precede the onset of conditions like Alzheimer's. As a popular over-the-counter sleep aid, melatonin use is widespread, but its long-term health implications are still not fully understood.

The details

Research suggests melatonin may have potential benefits for preventing heart disease and dementia, but the evidence is primarily from animal studies using much higher doses than typical OTC products. In humans, studies have shown modest improvements in sleep quality and cognition for those with existing sleep or cognitive issues, but no clear health advantages independent of melatonin's effects on sleep. Concerningly, one large study found an association between long-term melatonin use and increased risk of heart failure and mortality in adults with insomnia.

  • In 2024, a review examined melatonin's potential neuroprotective effects in animal studies.
  • A 2026 meta-analysis found melatonin use was associated with improved lipid profiles, reduced oxidative stress, and better sleep in patients with chronic kidney disease.
  • A 2021 review noted reduced circulating melatonin levels in various diseases, but it's unclear if supplements can reverse this.
  • A September 2025 report found higher rates of heart failure and mortality in insomnia patients prescribed melatonin long-term.

The players

Heidi Moawad, MD

A neurologist and medical editor who is on the teaching faculty at Case Western Reserve University.

Got photos? Submit your photos here. ›

What they’re saying

“Research suggests that melatonin has potential benefits for preventing heart disease and dementia, even in the absence of sleep disorders or sleep disturbances.”

— Heidi Moawad, MD, Neurologist

“The correlation between low circulating melatonin levels and poor health has been documented in humans. According to a 2021 review, 'circulating melatonin levels are consistently reduced in the metabolic syndrome, ischemic and non-ischemic cardiovascular diseases and neurodegenerative disorders like the Alzheimer's and Parkinson's diseases.'”

— Heidi Moawad, MD, Neurologist

What’s next

More long-term, large-scale studies are needed to fully understand the potential benefits and risks of melatonin supplementation, especially in relation to cardiovascular and cognitive health outcomes.

The takeaway

While melatonin remains a popular over-the-counter sleep aid, the evidence for its broader health benefits is mixed. Physicians should carefully consider patients' melatonin use and focus more on promoting healthy sleep hygiene practices rather than relying on supplements.