Blue light—a range of the visible light spectrum emitted by most white LEDs and most tablet and phone screens—could be hazardous to our health, a new study shows. Researchers from the Barcelona Institute for Global Health analyzed the blue light exposure and medical histories of 4,000 people throughout Spain, also utilizing nighttime images taken by astronauts in the International Space Station to assess exposure of residents of Barcelona and Madrid.

They found that those exposed to more blue light at night had between 1.5 to two times the risk of prostate and breast cancer. “Given the ubiquity of artificial light at night, determining whether it increases or not the risk of cancer is a public health issue,” says lead author Ariadna García.

This article appears in the December 2018 issue of Natural Awakenings.