Article publication date
October 2025
ARPANSA review date
December 2025
Summary
This prospective cohort study assessed the association between light exposure (day and night) and incidence of cardiovascular diseases in human populations. A total of 88,905 individuals (mean age, 62 years) were included in the study. The data on light exposure from the participants (nearly 13 million hours) were collected from using wrist-worn light sensors. The information on the incidence of cardiovascular diseases (e.g., coronary artery disease, myocardial infarction, heart failure, etc. after light tracking) were gathered from UK National Health Service records. The strength of the association was reported in hazard ratios (HRs) with a 95% confidence interval (CI) adjusting for potential confounders (e.g., sociodemographic and lifestyle, sleep, physical activity, diet and genetic susceptibility). The results [HR (95% CI)] showed that exposure to brighter light at night was associated with higher risks of coronary artery disease [1.3 (1.2-1.5)], myocardial infarction [1.5 (1.3-1.7)], heart failure [1.6 (1.3-1.8], atrial fibrillation [1.3 (1.2-1.5)], and stroke [1.3 (1.1-1.5)]. The study indicated that light at night exposure is a risk factor for cardiovascular disease in adults over 40 years old.
Published in
JAMA Network Open
Link to study
Light Exposure at Night and Cardiovascular Disease Incidence
ARPANSA commentary
The study reports that brighter night light is related to up to nearly 60% higher risk of cardiovascular disease among the people aged 40 years and older. These risk estimates are comparable to those reported in previous smaller studies (e.g., Obayashi et al., 2015; Kim et al., 2023). The strength of the current the study lies in rigorous adjustment for confounding variables and the inclusion of personal light exposure data. Notably, this was the first study on light exposure to account for key cardiovascular risk factors (BMI, sleep, diet, hypertension, cholesterol, and diabetes) thereby disentangling the effects of these factors from those of light exposure.
One of the key limitations of the study is that it predominantly included white (97%) populations and people with higher education levels, higher income, women (57%), and healthier individuals. This eventually flags the study findings while generalising them for other human populations. However, the findings suggest that limiting overexposure of night light is another factor that could help reduce cardiovascular disease risk associated with it. There are some publications which provide useful recommendations for visible light exposure, such as from light emitting diodes, and potential health effects (e.g. ANSES, 2019; Brown et al., 2022). Similarly, the International Commission on Non-ionizing Radiation Protection (ICNIRP) has published a statement on short wavelength light (SWL) exposure from indoor artificial sources and human health acknowledging no scientific consensus on whether night light per se causes health effects. ARPANSA currently does not have specific health advice regarding night light exposure and health. However, it will continue to scrutinize emerging evidence on health risk associated with night light exposure.
