Working the Night Shift May Increase Your Risk of Getting Breast Cancer

New research shows whether you like working at night or you simply don’t have a choice doesn’t matter—you’re still at risk for breast cancer. According to a study published in the journal Occupational and Environmental Medicine, people who work the night shift are more likely to get breast cancer than those who have regular day jobs. Apparently, once your internal body clock is disrupted, you risk altering some of your body’s hormones, which in turn are associated with the disease. 

Researchers studied 18,500 women who were part of the Danish Army between the years 1964 to 1999 to find out whether working at night really does increase the risk of getting breast cancer. They then followed up with 141 of the women who were diagnosed with breast cancer by 2005 to 2006, analyzing the results alongside the medical history of the 551 who didn’t have the disease. The participants were also asked to answer a 28-page questionnaire, which asked, among other things, whether they were night or morning people. 

Even after accounting for factors like hormone replacement therapy and the number of children the participants had,  the results revealed that working the night shift is still associated with a 40-percent increase in breast cancer risk. In addition, women who worked the night shift three times a week for six years also had twice the risk of getting cancer than those who worked the late shift once or twice a week.  Morning people who were assigned to work the night shift were even more at risk. 

Is there an explanation for all of this? According to researchers, working the night shift changes your circadian rhythm which, in turn, modifies your melatonin levels. For those who have regular day jobs, their melatonin levels are able to rise at night when the lights are switched off. Unfortunately, night shift workers are constantly exposed to artificial light, which only serves to limit melatonin creation. Breast cancer patients are also more likely to have lower levels of melatonin.

Despite the seemingly alarming news, the study also reports that working the night shift once or twice a week probably won’t do lasting damage. Just to be on the safe side, however, make sure you take care of your health. Don’t push yourself too hard, and get enough rest. 

(Photo by Jerry Bunkers via Flickr Creative Commons)