Artificial Light at Night Significantly Raises Cardiovascular Disease Risk, Study Shows
New research links increased artificial light exposure at night to significantly higher risks of cardiovascular diseases by disrupting biological rhythms.
- • Exposure to bright artificial light at night raises risk of heart disease by 45-56%.
- • Risk increase remains even after controlling for lifestyle factors.
- • Disruption of circadian rhythms by light affects sleep and metabolism.
- • Global nighttime lighting has increased nearly 50% since 1992.
Key details
A recent large-scale study has revealed that excessive exposure to artificial light at night drastically increases the risk of cardiovascular diseases such as coronary heart disease, heart failure, atrial fibrillation, myocardial infarction, and stroke. Conducted by Daniel Windred and his team at Monash University in Melbourne, the research involved 88,905 adults aged over 40 who wore wrist sensors for a week, accumulating over 13 million hours of light exposure data. Findings showed a 45 to 56 percent increased risk of various heart issues for those exposed to high levels of artificial light during the night compared to those with minimal exposure. The risk of strokes and coronary heart diseases specifically rose by 28 to 30 percent among individuals exposed to bright bedroom light at night. Crucially, these associations remained significant even after adjusting for lifestyle factors including smoking, alcohol use, diet, and sleep duration.
The study emphasizes the role of the body's internal biological clock, governed by the brain's suprachiasmatic nucleus (SCN), which regulates vital functions such as sleep, metabolism, hormone production, and body temperature. The SCN receives light signals that promote wakefulness during the day, while darkness triggers the release of melatonin to induce sleep. Artificial light exposure at night disrupts this circadian rhythm, potentially causing elevated heart rates, high blood pressure, and impaired insulin sensitivity, effects similar to those seen in shift work.
Global nighttime lighting has surged by nearly 50% from 1992 to 2017, especially in urban areas where darkness is increasingly scarce, posing a growing public health challenge. Despite the study's robust findings, limitations include a primarily white, well-educated cohort, highlighting the need for further research, including investigating the effects of light color. To reduce cardiovascular risks, the researchers recommend minimizing nighttime light exposure through measures such as closing curtains, wearing sleep masks, and turning off electronic devices before bed.