Working the night shift has already been linked to higher risks of cancer and cardiovascular disease. Now researchers at Harvard—who've combed through 22 years of data tracking 75,000 nurses in the US—write in the American Journal of Preventive Medicine that rotating night shifts for five or more years results in higher mortality rates in women. Specifically, death from cardiovascular disease is as much as 23% higher and death from lung cancer is as much as 25% higher, reports Fox News.
"These results add to prior evidence of a potentially detrimental relation of rotating night shift work and health and longevity," the lead researcher says. Rotating shift work is defined as working at least three nights a month in addition to working day and evening shifts. And while the researchers acknowledge that more study is needed to learn how a person's individual traits might play a role, people who work rotating night shifts for more than five years do experience an 11% hike in risk of death from all causes, reports HealthDay News. (Researchers blame the disrupted balance of light and dark in the increased cancer rates.)