The latest meta-analysis of the effects of the clock changes on acute myocardial infarction reported a 4% increase after the spring clock change, but substantial heterogeneity was present in study results and designs.4 We found initial evidence of a 2% increased risk of acute cardiovascular disease in the week after the spring clock change, which was not supported by sensitivity analyses examining the effect of individuals having multiple events. Here, CLOCK is linked to myocardial infarction.