Light pollution, once an unfamiliar term, has become an urgent global concern as its impact on human health becomes increasingly evident.
Approximately 80 per cent of the world’s population is now exposed to significant levels of artificial light at night, from streetlights to indoor screens, according to experts.
Scientists are warning that this excessive exposure can lead to serious health problems, ranging from sleep disorders to more severe conditions like breast cancer, stroke, and heart disease.The full extent of light pollution’s health effects remains under investigation, but experts agree that the disruption of circadian rhythms, similar to the impact on wildlife, plays a critical role.
“Human evolution was characterized by bright days, dim evenings, and dark nights. We’ve changed this drastically, and while some people adapt, others face significant health risks,” said George Brainard, director of the Light Research Program at Thomas Jefferson University in Philadelphia.Over the past few decades, artificial lighting in urban areas has grown by more than 2% annually.
A significant contributor to the problem is the widespread use of light-emitting diode (LED) bulbs. Originally introduced for their energy efficiency, LEDs emit shorter-wavelength blue light, which has been found to suppress melatonin—a hormone vital for sleep and cancer prevention—at ten times the rate of longer-wavelength, amber light. Indoor lighting, particularly from screens and devices, compounds the problem.
“Blue light exposure from these sources significantly impacts sleep quality and increases the risk for various illnesses,” said Mario Motta, a retired cardiologist who served on the American Medical Association’s Council on Science and Public Health.Minority communities, often subjected to excessive outdoor lighting due to misguided crime prevention strategies, are disproportionately affected, according to Travis Longcore, an urban ecologist at UCLA.
He labels light pollution an “environmental justice issue,” as these communities face higher health risks related to poor lighting conditions.Evidence supporting the link between light pollution and cancer is growing. Studies have found elevated rates of breast, colon, and prostate cancers in areas with the highest levels of artificial light. Recent research even suggests a connection between bright outdoor lighting and childhood leukemia.Efforts to reduce light pollution have been slow.
The Illuminating Engineering Society only began advocating for healthier outdoor lighting in 2020, urging communities to minimize blue light, use lower-intensity bulbs, and install shielding to direct light more effectively. However, many municipalities have yet to adopt these changes.In the meantime, individuals can take steps to protect their health by dimming lights at night, using blackout curtains, and adjusting device settings to warmer tones in the evening. “Reducing exposure to circadian-disrupting light during wind-down hours is essential for maintaining healthy sleep and overall well-being,” said Brainard.
As researchers continue to investigate the broad-reaching consequences of light pollution, the need for increased awareness and action becomes ever more pressing.
