New York, Aug 18: Women who work under artificial light in night shifts at an increased risk of developing breast cancer as it blocks a hormone that plays a key role in suppressing growth of its tumours, claims a study.
The study showed that women who were premenopausal and were current or past smokers, and also who live in areas with high levels of outdoor light at night, were at risk of developing breast cancer.
“In our modern industrialised society, artificial lighting is nearly ubiquitous. Our results suggest that this widespread exposure to outdoor lights during night time hours could represent a novel risk factor for breast cancer,” said lead author Peter James, Assistant Professor at Harvard University.
Melatonin, a hormone produced in the human brain, appears to suppress the growth of breast cancer tumours but exposure to light may decrease its levels that govern sleepiness and lead to increased breast cancer risk.
For the new study, nearly 110,000 women and data from satellite images of Earth taken at night to residential addresses for each study.
The results showed that women exposed to the highest levels of outdoor light at night 14 per cent increased risk of breast cancer.