The American Heart Association released a study today that will be summarized tomorrow as "melatonin linked to heart failure," and the summary will be both accurate and misleading. Researchers used a large database of electronic health records to find about 130,000 adults with chronic insomnia, matched some 65,000 who had taken melatonin for a year or more against similar people who had not, and followed them for five years. Melatonin users were diagnosed with heart failure at a rate of 4.6% versus 2.7%, were hospitalized for it at 19% versus 6.6%, and died at 7.8% versus 4.3%. The work is an abstract to be presented at the association's scientific sessions in New Orleans, which begin later this week. It has not been peer-reviewed or published.
The number the headline won't give you. It is the word "association." People who take melatonin every night for a year are people whose insomnia did not resolve, and chronic insomnia is itself associated with heart disease. A database can match for age, sex and diagnoses on the record; it cannot match for how badly you sleep, and it cannot see the millions of Americans who buy melatonin over the counter without a prescription and never appear in the data at all. The authors say this themselves. What the study can fairly say is that long-term melatonin use marks a group of people who do worse — and that is reason enough to ask why they are still taking it. Melatonin is sold in the US as a dietary supplement, which means its contents are not held to drug standards and no one has had to show it works for chronic insomnia; in much of Europe it is a prescription drug.
Loree’s takeThe first-line treatment for chronic insomnia is not a pill of any kind. It is cognitive behavioral therapy for insomnia, which has the strongest evidence of anything in the field and which almost none of my patients have been offered before they arrived at a gummy. Melatonin has a real but small role in shifting the body clock — jet lag, shift work — and that role is measured in days. A year of nightly use is a sign that the actual problem was never addressed. That is what today's study is really describing.
Ben’s takeMelatonin is a few dollars a bottle, and the headline will push people to a hundred-dollar sleep device instead. Neither is the answer. The thing that treats chronic insomnia is a short course of structured behavioral therapy that no supplement company and few device companies have an incentive to sell you, because you only buy it once. The study is a reason to stop treating a chronic condition with a nightly purchase. It is not a reason to make a bigger one.
Why it matters to a recovering optimizer. Tomorrow's version of this study will frighten people off melatonin without telling them what to do instead, which is the failure mode of nearly all health news. The evidence-based answer existed before the abstract and does not depend on it: for insomnia that has lasted months, ask for CBT-I. For the gummy, ask what it is still for.
If you have taken a sleep aid nightly for a year, the question isn't which aid. It's why the insomnia was never treated.
This post reports on evidence and expert disagreement. It is not medical advice; decisions about treatment belong with you and your clinician.