A research team from Harvard Medical School in Boston has presented the results of a large-scale analysis focused on how nighttime exposure to artificial light impacts adult health. The specialists used advanced brain and vascular imaging techniques to assess how artificial light after dark affects internal bodily processes.
The study involved 450 participants without chronic heart disease or active cancer. Each underwent a comprehensive evaluation, including positron emission tomography and computed tomography. This approach allowed researchers to simultaneously assess stress levels in the brain and the degree of inflammation in the arteries.
The findings revealed that the higher the level of artificial lighting at night, the stronger the stress reactions in the central nervous system and the more pronounced the inflammatory processes in blood vessels. These changes are directly linked to an increased risk of cardiovascular disease.
Heart risks: how light affects blood vessels and the brain
An analysis of participants’ medical data revealed a clear pattern: every standard deviation increase in nighttime light exposure was associated with a 35% higher risk of heart disease over five years and a 22% increase over a ten-year period. This relationship persisted even after accounting for other factors such as noise levels, socio-economic status, and residents’ habits.
People living in areas with high external stress—such as near busy roads or in low-income neighborhoods—were found to be particularly vulnerable. Over ten years, 17% of participants developed serious heart conditions, underscoring the significance of the issue for urban populations.
Researchers note that even a moderate increase in nighttime lighting can trigger negative changes in brain and vascular function. Moreover, the relationship between light exposure and disease risk proved to be almost linear: the brighter the light at night, the greater the likelihood of heart problems.
Practical tips: how to reduce the harmful effects of nighttime lighting
The authors of the study emphasize that the negative impact of artificial light can be reduced both at the urban planning level and at home. Suggested measures include reducing unnecessary outdoor lighting, installing light-sensitive street lamps, and shielding street lights. At home, experts advise keeping bedrooms as dark as possible, avoiding nightlights, and refraining from watching TV or smartphone screens before bed.
According to experts, such simple steps can help ease the strain on the cardiovascular system and lower the risk of dangerous diseases. In today’s urban environments, where artificial lighting levels are steadily rising, these recommendations are especially relevant for maintaining good health.
The study highlights the importance of a comprehensive approach to lighting in cities and residential areas. Monitoring nighttime light levels could become one of the key factors in preventing cardiovascular diseases in the future.
