WORLD (Enmaeya News) - November 27, 2025

A new large‑scale study finds that exposure to light at night, even modest levels, is linked to a significantly higher risk of cardiovascular disease, including heart attacks, heart failure, arrhythmia, and stroke.

The research, presented at the American Heart Association (AHA) Scientific Sessions 2025, analysed data from about 88,900 adults over roughly 9.5 years.

Participants wore wrist‑mounted light sensors for a week to estimate their personal night‑time light exposure; those with the brightest nights had up to a 1.56‑times greater risk of heart failure, 1.47‑times greater risk of heart attack.

The biological mechanism appears linked to disruption of the body’s natural circadian rhythm: night‑time light seems to trigger stress responses in the brain that lead to inflammation of blood vessels, a precursor to heart disease.

Previous smaller‑scale studies also showed that even one night of moderate light exposure during sleep can raise heart rate, impair heart‑rate variability, and increase insulin resistance the next morning.

While the authors note that their findings are robust even after adjusting for traditional heart‑disease risk factors, they caution that light exposure at night is a potential environmental factor that could be addressed to reduce cardiovascular risk.

Public‑health experts say the study underscores the importance of the sleep environment: ideally, bedrooms should be as dark as possible.

Practical tips include using blackout curtains, minimizing indoor lighting after sundown, avoiding screen use close to bedtime, and covering sources of ambient light.

As urbanization increases and night‑time light pollution becomes more widespread, especially in dense cities, these findings may have important implications for populations globally, including in the MENA region, where many live in light‑polluted environments.