A new study from Harvard has found greater risk of breast cancer in women who live in neighborhoods that have higher levels of outdoor light during the night.
The findings are based on the Nurses’ Health Study (NHS), which has for decades been advancing our understanding of risks to women’s health.
For this study, epidemiologist Peter James and colleagues followed nurses in the NHS for breast cancer occurrence from 1989 to 2013.
The home of each of 109,672 nurses was geocoded, and the average light level in the immediate neighborhood at night was estimated from satellite images taken by the Defense Meteorological Satellite Program.
These estimates were…