In a recent study from Harvard University, researchers have found that women potentially have a greater risk of developing breast cancer if they live in neighborhoods that have high levels of outdoor night lighting. These findings are based on the Nurses’ Health Study, known for advancing understanding of risks to women’s health.
This study followed approximately 109,672 nurses in the NHS for occurrences of breast cancer from 1989 to 2013. The home of each nurse was geocoded and the average light level in the neighborhood was measured by satellite images taken by Defense Meteorological Satellite Program.
By 2013, a total of 3,549 new cases of breast cancer had been diagnosed. This number was what they expected among that sample size of women. The study found a direct correlation between the neighborhood nighttime light level before diagnosis and the later risk of developing breast cancer. Researchers said that these findings held up even after filtering out other risk factors, such as age, number of children, weight, use of hormone medications and others.
Too much electric light at night might explain a portion of the breast cancer pandemic that dates back to 1987.
The question is… How does nighttime light levels outside the home in a woman’s neighborhood affect the risk of breast cancer?
Studying the outside light levels, it is assumed that if communities shine so brightly to a satellite are composed of people who are in general bathed in light. They tend to have greater light exposure in the home, outside on the street, and for evening entertainment in the city. Satellite data are thought to be a surrogate, or a proxy, for this actual LAN exposure to each woman, particularly in the evening before sleep. The body’s normal transition to nighttime physiology should begin at dusk. The hormone, Melatonin, rises in the blood substantially at night.
Melatonin has been shown to have cancer fighting effects in lab rats.
Artificial night lighting, which has a short wavelength compared with natural light, leans toward the blue spectrum relative to other colors. This has a greater impact on lowering melatonin, delaying the transition to nighttime physiology.
The higher the nighttime light level, the higher the risk.