Working night shifts can be inconvenient and challenging, but most people eventually adapt to working when it’s dark outside and sleeping during the day. But all may not be rosy for women working night shifts. According to research, night shiftwork could increase a woman’s risk of breast.
Shift Work and Cancer: Is There an Association?
Two studies published in the Journal of the National Cancer Institute in 2001 that looked at night shiftwork and the risk of breast cancer came to some disturbing conclusions. In one case-control study where researchers interviewed over 800 women with and without breast cancer, they found the risk of getting breast cancer was 14% higher in women who worked night shifts. Another prospective study involving almost 80,000 women came to a similar conclusion – working night shifts raises breast cancer risk.
On a more positive note, researchers believe the risk may not apply to all women who work when they should be sleeping. The women in the second study worked night shifts for thirty or more years, which isn’t typical of the general population. It’s also not clear how night shiftwork affects men or whether it increases the risk of other types of cancer.
How Does Night Shift Work Increase the Risk of Breast Cancer?
At night when the human eye is deprived of light, it stimulates a tiny gland in the brain called the pineal gland to produce melatonin. Melatonin is a hormone with strong antioxidant benefits, and it plays a role in estrogen metabolism. When melatonin levels are suppressed by a lack of darkness, it may raise estrogen levels – which could stimulate growth of an estrogen-dependent breast cancer. Interestingly, studies show that women with breast cancer often have low levels of melatonin, which adds more support to this theory.
Shift Work and Cancer: The Bottom Line?
Working night shifts over many years could increase the risk of breast cancer by altering melatonin levels. Should shift workers take a melatonin supplement to reduce their risk? Although melatonin supplements can be found at most health food stores, no one knows if they’re safe to take longer term. Plus, there’s always concern about the quality and purity of such supplements. People who work night shifts and sleep during the day may benefit from wearing a sleep mask that completely blocks out all light. Even better? Find a job where you don’t have to work night shifts.
Journal of the National Cancer Institute (2001;93:1557-1568).
Medical News Today. “Shift Work And Cancer”