Working the Night Shift Could Raise Your Cancer Risk

From TIME - January 8, 2018

Working the night shift is linked to a number of health issues, from heart disease to obesity to sleep disordersand even cancer. Now, in a new report, researchers in China have found that women who work the night shift have a 19% increased risk of developing cancer compared to women do not work at night.

The research, published in Cancer Epidemiology, Biomarkers & Prevention (a journal of the American Association for Cancer Research), was an analysis of 61 studies that included nearly four million people from North America, Asia and Australia.

When the researchers looked more closely at the types of cancer the women were getting, they found that women who worked night shifts for longer periods of time had a 41% higher risk of skin cancer, 32% higher risk of breast cancer and an 18% greater risk of digestive system cancers compared to women who did not work night shifts. The risk was highest among nurses who worked at night; their risk of developing breast cancer if they worked night shifts long term was 58% higher than nurses who didnt have night shifts.

MORE: How Late Nights at the Office Can Harm Your Heart

Xuelei Ma, senior author of the paper and assistant professor at Sichuan University, says that the longer women worked night shifts, the higher their risk. For every five years of night shift work, the risk of breast cancer, for example, went up by 3.3%.

The increased risk, particularly among female nurses, does not necessarily mean that women who work night shifts are more vulnerable to developing cancer, Ma notes. In the case of nurses, for example, their higher rates may simply reflect the fact nurses are more likely to get screened and therefore receive a cancer diagnosis than the average woman. All of the studies included in the analysis may not have adequately accounted for other factors linked to cancer rates, such as diet, physical activity and sleep habits.


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