Reacción a "Continued use of melatonin for insomnia is associated with an increased risk of heart failure"

Melatonin is a product that, although not without adverse effects, is usually very well tolerated, with a risk-benefit ratio in favour of its use, even in children.

Therefore, the abstract of this study is surprising, as it shows results not previously described and which raise doubts:

• It is an observational study (with its limitations).
• It only mentions an association, with no apparent evidence of a causal relationship between melatonin use and subsequent heart failure.
• It is unclear whether the control group were melatonin users without medical supervision, given the easy access to this product in some countries.
• This is a study presented at a scientific meeting, whose evaluation (by a scientific committee) is not as strict as the peer review (by two independent reviewers) carried out by scientific publications.
• It contrasts with the conclusions of recent meta-analyses regarding the use of melatonin, even in ICUs (Kelleher et al-PLoS One, Tang et al 2025, Darily et al 2025, the latter even describing an improvement in cardiac function).

However, these discrepancies are beneficial to science and raise a very positive debate, with the need for prospective studies with a “well-controlled” control group to ensure the safety profile of melatonin.