A study published in the Occupational and Environmental Medicine that sampled over 1,000 women—389 of whom were in the primary stages of the most common form of ovarian cancer—and 1,832 cancer-free women has determined that working night shifts increases the risk of ovarian cancer. The women interviewed are from 35 to 74 years old, and work in fields including health care, food service and office administration.
The International Agency for Research on Cancer had previously classified this type of shift work as a cancer trigger because it disrupts the body's internal clock. Despite this, studies between shift work and breast cancer have always been inconclusive.
In the present study, one in four women with invasive ovarian cancer had worked night shifts compared to one in three women that had borderline disease. About one in five women in the control group (those without the cancer) had worked night shifts. [...] Data analysis showed that night shifts alone increased the risk of invasive ovarian cancer by 24 percent and borderline disease risk by 49 percent.
24% is pretty damn significant, and the rate increases even more for women over 50. Researchers suspect this has something to do with the night shift workers' adjusted melatonin production, which is produced at night but suppressed by light. Melatonin helps to regulate hormones, particularly estrogen.
Additionally, of the night shift workers sampled, 27% classified themselves as "night owls" and 20% as "morning larks" (Put a bird on it?) Researchers discovered that the risk of advanced ovarian cancer was higher among the larks than the owls. Not that anyone really has to make a case for sleeping in, but maybe not being a morning person isn't as bad a habit as we thought.
'Night Shift Linked to Raised Risk of Ovarian Cancer' [US News & World Report]
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