In this case, the study looked at data from nearly 110,000 women who enrolled in the Nurses’ Health Study II from 1989–2013, one of the largest studies of risk factors for serious chronic diseases in women.
James and his team linked data from satellite images of Earth taken at night to the residential address of each study participant. He and his team also considered the influence of night shift work, and factored in detailed information on a variety of health and socioeconomic factors among the participants.
The researchers identified 3,549 incidents of breast cancer among the women in the study. An association between exposure to light at night and breast cancer was seen, not only in premenopausal women and current and past smokers, but also among those women who worked night shifts.
RELATED: Tanning Compound Produces Protective Melanin in Skin Without the Sun
Night nurses and others who work in the evenings and early morning hours have no choice but to be exposed to ample artificial light. Even those of us who do not work the graveyard shift might often look at our televisions, cell phones, laptops, and other artificially lit devices in the evenings.
Street lamps, neon business signs, and other artificial outdoor lighting surround many of our homes. All of this begs the question: Can even short-term, yet regular, exposure to artificial light at night also lead to health problems?
“Although our study did not examine this question, previous studies have shown that exposure to light from electronic devices may suppress melatonin and shift the circadian clock,” James said. “I do not think we know enough to say exactly how frequent or chronic exposure to this type of light would have to be to influence health outcomes.”
Women aren’t the only ones at potential risk, either.
James said that other prior research has suggested that night shift work and exposure to light at night could be linked to several types of cancer, including prostate cancer.
Increased incidences of diabetes, heart disease and obesity related to the same factors have also been reported.
“So, the risks of exposure to light at night may not be confined to women,” James said, “but again, this area requires a great deal more research before we can make definitive recommendations.”
WATCH: Light Pollution Is More Dangerous Than You Think