Insomnia and the Risk of Atrial Fibrillation: A Nationwide, Real‐World Cohort Study

Background Insomnia is one of the most prevalent diseases observed in clinical practice, contributing to increased death and a range of chronic diseases. While numerous studies have explored the relationship between insomnia and cardiovascular disease, research on its association with atrial fibrillation (AF) remains limited. This study aimed to investigate the association between insomnia and incident AF in the general population by comprehensive, nationwide, real‐world data in Japan. Methods A total of 1 780 764 individuals without prior cardiovascular disease including AF from the DeSC database were included between April 2014 and August 2023. Insomnia was defined by International Classification of Diseases , Tenth Revision ( ICD‐10 ) codes (F510, G470) before the baseline health checkup. The primary outcome was incident AF (I480–I482 and I489). Cox proportional hazards models were used to estimate hazard ratios of AF according to present insomnia (versus absent). Results Insomnia was observed in 216 919 individuals (12.2%), showing a significant association with incident AF after adjusting for potential confounding factors (adjusted hazard ratio, 1.14 [95% CI, 1.10–1.18]). Among subgroups, a similar pattern in the association between insomnia and incident AF was seen, while the association was stronger in younger individuals aged