These days, it's just good to have a job. But remaining gainfully employed can take a toll on health, especially if your work has you up at odd hours and sleeping irregularly. Shift work, say two studies out this week, poses particular problems for women, who appear to be at greater risk of Type 2
if they maintain work schedules that mess with their internal clocks.
Researchers have uncovered a
between humans' respect for their circadian rhythms and their health prospects. Those who toil while their neighbors rest, or who have chronic sleep deficits, are more likely to suffer a wide range of health problems, besides just being tired: They're more likely to be
, and to have
published this week in the journal PLoS Medicine, researchers tracked the extent to which more than 175,000 participants in the Nurse's Health Study and its follow-up study, the NHS II, worked "rotating night shifts" over the 18 to 20 years of their participation in the study. (Nurses, of course, attend their patients around the clock, so it is a profession notorious for rotating shifts.)
Those who had spent more than 20 years rotating their work schedules so they sometimes worked nights were almost 60% more likely than women who had never worked rotating shifts to develop Type 2 diabetes. Women who had racked up less time doing shift work also were at higher risk for developing the metabolic disorder, but less so than long-timers (about 20% for women who had donethree to nine years of shift work and 40% for those who had rotated work schedules bewteeen night and day for 10 to 19 years).
The researchers noted that
appeared to be a potent contributor to the trend, and that obese shift-working women appeared at greatest risk of diabetes.
Also out this week, a comprehensive
and environmental factors cited "growing evidence" that shift work is "probably associated with increase risk for breast cancer," and called for more research to define that link and explore what measures--aside from quitting your night job--might mitigate the effect.
The panel, which prepared the
at the request of the
foundation, speculated about why shift work might boost breast cancer risk, including evidence that irregular sleep patterns disturb the proper function of hormones, and that "clock
," knocked off-kilter by irregular sleep patterns, may set off cancerous cell growth in breast tissue.