The 2025 warning was an association
An American Heart Association meeting report described 130,828 adults with insomnia, comparing recorded melatonin use for at least a year with matched non-users. Reported five-year incident heart failure was 4.6% versus 2.7%. This is not a finding that 90% of users developed heart failure. The report was preliminary, and unrecorded over-the-counter use, insomnia severity and other differences could affect the association. [1]
The newer analysis did not answer the same question
A 2026 NHANES analysis included 50,929 adults, only 267 of whom reported recent melatonin use. After adjustment, use in the previous 30 days was not significantly associated with existing cardiovascular disease or heart failure. This cross-sectional result cannot establish what happens after years of use or directly refute a study of new diagnoses in people with insomnia. [2]
Treatment research is not proof of prevention
A 2026 review of 14 randomized cardiovascular trials found some favorable measures, particularly in cardiac-surgery settings, but inconsistent results across outcomes. Small samples, differing conditions and low-certainty evidence limit conclusions. Hospital adjunct trials do not show that a retail sleep supplement prevents heart failure in otherwise healthy users. [3]
Review the reason for continued use
Imagine someone takes melatonin nightly and is worried by a headline. Discuss the sleep diagnosis, duration, formulation and other medicines with a clinician, especially with cardiovascular disease or multiple prescriptions. Do not stop prescribed cardiac treatment or increase melatonin for a proposed antioxidant benefit. [2][4]
| Evidence | Main limitation |
|---|---|
| 2025 insomnia cohort | Confounding and incomplete exposure records |
| 2026 recent-use survey | Cannot establish long-term effects |
| Cardiovascular treatment trials | Specialized heterogeneous settings |
| Personal treatment decision | Needs individual review |
Sources for this article
- Long-term use of melatonin supplements to support sleep may have negative health effects | American Heart Association
Source consulted: 2026-09-21. This is a reference resource, not a claim that we conducted the studies or tested a product. - Melatonin and cardiovascular risk: an NHANES reality check after recent heart failure concerns - PMC
Source consulted: 2026-09-21. This is a reference resource, not a claim that we conducted the studies or tested a product. - Melatonin Supplementation and Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Randomized Trials - PMC
Source consulted: 2026-09-21. This is a reference resource, not a claim that we conducted the studies or tested a product. - Taking melatonin with other medicines and herbal supplements - NHS
Source consulted: 2026-09-21. This is a reference resource, not a claim that we conducted the studies or tested a product.