Outdoor Night Lights : A new risk factor for breast cancer?

map of the USA showing lights in major cities during the night

Researchers at the Harvard T.H. Chan School of Public Health recently published a study that identified an unexpected risk factor for breast cancer: outdoor nighttime lights.

Through a study conducted over a span of 22 years and with 110,000 female participants, researchers observed that women who lived in areas with higher exposure to outdoor artificial lighting were more likely to develop breast cancer during their lifetime compared to their counterparts who were less exposed to nighttime lights. Overall, compared to the group with the lowest exposure, the group of women that was exposed to the most nighttime light was at a 14% increased risk to develop breast cancer. This risk was especially visible in young women and smokers (both current and former).1

Even though the exact way that light could impact cancer is not known, there might be health benefits from shielding oneself from night lights. But...how does one escape from the city lights?!

  • 1 Peter James, Kimberly A. Bertrand, Jaime E. Hart, Eva Schernhammer, Rulla M. Tamimi, and Francine Laden. 'Outdoor Light at Night and Breast Cancer Incidence in the Nurses' Health Study II' (2017) Environ Health Perspect. 125(8):087010 doi: 10.1289/EHP935 [Article Link]
Image Credit
By NASA Earth Observatory [Public domain], via Wikimedia Commons