Context

Increasing evidence suggests a relatively strong association between insomnia and risk of future cardiovascular events. However, the exact nature of this association is poorly understood and causality remains uncertain due to methodological limitations in prior literature. An important methodological shortcoming was the inadequate consideration of comorbidities in several previous studies. Insomnia symptoms clearly overlap with those of depression, and could be caused by other sleep disorders, most importantly by obstructive sleep apnoea and by several somatic diseases which could increase the risk for cardiovascular diseases.

Hsu and colleagues took advantage of a large nationwide health database and investigated the long-term association between insomnia and myocardial infarction and stroke, …