Working the night shift for an extremely long period of time can lead to an increased risk for breast cancer, according to researchers in Canada.
The research, which was published last week in the journal Occupational and Environmental Medicine, indicates that women who work nights for 30 years are twice as likely to develop breast cancer than women who work normal hours.
However, the researchers have not yet determined why this happens.
"We would like to know what it is about shift work that's causing this increased risk," Dr. Anne Grundy, who authored the study from the Ontario Cancer Clinic, told Medscape. "If we did, we might be able to design shift schedules that are better for health."