Artificial Light at Night and Stroke Risk: A Prospective Cohort Study from the UK Biobank

Background

Artificial light at night (ALAN) is a widespread environmental exposure that disrupts circadian rhythms and is linked to cardiometabolic diseases. Stroke remains a leading cause of mortality globally, and a major public health burden in Europe, yet evidence on ALAN and stroke risk is limited. This study examines the association between long-term ALAN exposure and incident stroke.

Methods

We analyzed 484,556 UK Biobank participants free of stroke at baseline. Satellite-derived nighttime radiance data (2010–2021) were linked to residential coordinates to estimate ALAN exposure, categorized into low, intermediate, and high levels. Incident stroke was identified through linked hospital and mortality records. Cox proportional hazards models were applied with sequential adjustment for demographic, clinical, and socioeconomic factors. Restricted cubic spline models assessed non-linear relationships.

Results

During a median follow-up of 4,382 days, 10,527 incident stroke cases were recorded. High ALAN exposure was associated with increased stroke risk in crude (HR = 1.07; 95% CI: 1.02–1.12) and age-sex adjusted models (HR = 1.17; 95% CI: 1.12–1.22). The association remained significant after clinical adjustment (HR = 1.11; 95% CI: 1.07–1.16) but attenuated after adjustment for deprivation (HR = 1.03; 95% CI: 0.98–1.08). Non-linear analyses suggested peak risk at intermediate exposure levels, with attenuation after socioeconomic adjustment.

Conclusions

ALAN exposure was modestly associated with stroke risk, but this relationship was largely explained by socioeconomic factors. These findings highlight the need to address environmental exposures alongside social determinants of health. Reducing excessive nighttime lighting and integrating environmental considerations into urban planning may support stroke prevention.

Key messages

• Artificial light at night exposure is linked to increased stroke risk, but this association is largely driven by underlying socioeconomic inequalities.

• Addressing light pollution alongside social inequalities may improve stroke prevention and highlight environmental exposure as a modifiable public health target.