Nighttime Light Exposure Linked to Higher Cardiovascular Risk

Higher nighttime light exposure was associated with adverse changes in cardiac structure and function and increased risks of cardiovascular disease (CVD) events and death. In this UK Biobank population-based study, 11,071 participants with 7-day wrist-worn light measurements and subsequent cardiac MRI were evaluated, with high nighttime light exposure (>3 lux) associated with 2.4% greater left ventricular (LV) mass, 1.5% greater mean wall thickness, and 1.9% lower myocardial contraction fraction, along with impaired LV circumferential, radial, and longitudinal strain. Adverse changes were also observed in the right ventricle and left atrium, suggesting remodeling and subtle functional impairment across multiple cardiac chambers. These associations showed linear dose-response relationships and were partly mediated by shorter sleep duration. In a larger cohort of 73,286 participants followed for 8–10 years, high nighttime light exposure was associated with 29% higher risk of heart failure, 15% higher risk of atrial fibrillation, 24% higher risk of myocardial infarction, 33% higher risk of stroke, and 26% higher risk of CVD mortality. These findings suggest that reducing nighttime light exposure and maintaining sufficiently dark nights and adequate sleep may be important for cardiovascular health, although the observational design does not establish causality. Source: https://academic.oup.com/eurheartj/