(NEW YORK) -- If you're a woman who works nights, new research from Canada says your hours may be increasing your risk of breast cancer. The latest study to find a connection between breast cancer, the second-most common form of the disease in U.S. women, and working nights appears online in Occupational and Environmental Medicine.
Researchers at the Queen's Cancer Research Institute at Queen's University in Kingston, Ontario, compared over 1,100 breast cancer patients with a like number of women who had no history of breast cancer.
They found that about a third of the women worked at jobs where they spent at least half their time on evening or night shifts. The breast cancer risk was more than twice as high for women with 30 years or more of night-shift work. For women who worked in health professions, the risk was higher still.
But what's the explanation?
Scientists suspect it involves melatonin, which regulates our daily body rhythms. Increased light exposure on night shifts may depress melatonin production and increase cancer risk.
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