Recent headlines have shrieked that melatonin is linked to a higher incidence of heart failure, hospitalizations, and death. What does the study actually say?

    The data were presented at a medical meeting in early November, but have not been published yet. The researchers used computerized medical records to compare the incidence of heart failure, hospitalizations for heart failure, and death in two groups of people with insomnia. One group consisted of patients whose medical records stated they took melatonin. For the other group, melatonin use was not mentioned. The study had the findings as below.

    Observational studies such as this are always debatable because the data can be extremely inaccurate. For example, some of the patients who are listed as not taking melatonin may in fact have been taking it and simply forgot when they filled out a questionnaire. This is especially likely because melatonin does not require a prescription.

    It is good that both the control group and the melatonin group had insomnia, because there are other causes for insomnia, such as sleep apnea, that can cause heart failure. However, patients who choose to spend their own money on melatonin may have had more severe insomnia. Those patients could be more likely to have other factors causing both their insomnia and their heart problems. While details of the research may not be available until official publication, in news articles I saw no mention of dosages of melatonin, or of the severity of the insomnia.

    What are the practical implications of this study? Bigger, better studies are indicated. However, I doubt that melatonin makers are going to finance such a study.

    While we wait for more information, if you take melatonin for insomnia, I would suggest you take as little as possible or consider discontinuing it. I have a collection of tips about insomnia on my website, and perhaps some of those would be helpful for you.

    A study such as this cannot truly prove that melatonin causes heart problems. The inflammatory headlines are annoying, but unfortunately common whenever a nutritional supplement is involved.