Melatonin and Your Heart: New Warning and What Science Knows

In this episode, I’m unpacking a new warning that caught a lot of people off guard: a late-2025 conference abstract suggesting long-term melatonin use may be linked to higher rates of heart failure and worse outcomes. The headline is scary, but I’m going to walk you through what it actually means, what it doesn’t prove, and why this one study raises questions that a single abstract can’t answer.I’ll explain why melatonin isn’t just a “natural sleep gummy.” It’s a hormone and a timing signal, a darkness message that helps run your circadian clock. And because your circadian system also helps regulate blood pressure, heart rate, vessel tone, and stress hormones, melatonin has real cardiovascular effects. I break down what we know about those effects (including the ways melatonin can lower nighttime blood pressure and shift the body into a calmer “rest-and-digest” mode), and why dose and timing matter more than most people realize.Then I get into the messy part: the evidence is mixed. There are studies suggesting melatonin could be protective in certain situations, yet there are also case reports and mechanisms that hint it might cause problems in specific people, especially at high doses or with certain health conditions. So I lay out the most plausible explanations for the new association (confounding from insomnia and other risk factors, masking symptoms, interactions, supplement quality issues), and how clinicians are thinking about it right now.If you take melatonin nightly or you’ve ever assumed it’s harmless because it’s “natural”this episode is my practical, science-first guide to what to do next: how to interpret the risk, what questions to ask your doctor, and why “lowest effective dose for the shortest necessary time” is the safest default until we have better data.Dr. Marbas Substack: https://drlauriemarbas.substack.com/A Big Thank You To Our Sponsors:If you want the best supplement to help you on your plant-based journey, you have to try Complement: https://lovecomplement.com/?aff=62 Get full access to The Habit Healers at drlauriemarbas.substack.com/subscribe