Dangers lurk behind night-shift work
By Ignacio Lobos, Fred Hutch External Communications Editor
Several years ago, my father, René, took a job with one of the most heinous schedules that could be imposed on a human being: a regular morning start for a week, followed by a swing-shift week, and finally, a week of work deep into the night, when everyone else was sleeping.
The three-week cycle went on and on, very quickly turning my father into a zombie. It didn’t take long for the brutal schedule to start affecting his health. Of course, it sure seemed to put a damper on his social life as well. And talk about making him grumpy!
Today, we know a lot more about the detrimental effects of working through the night. And with continued research, the case against working instead of sleeping only gets stronger.
A recent study, for example, found a strong connection between lost sleep and weight gain. Just losing a few hours of sleep over a few nights in a row was enough to trigger weight gains.
At Fred Hutch, researchers have been looking at the connection between late-night work and cancer, specifically among women. A study released in 2005 suggested a link between late-night shifts and an increased risk of breast cancer.
At the time, Fred Hutch researchers believed night-shift work could alter hormonal levels in women, exposing them to a greater cancer risk.
Another Fred Hutch study, published in the April issue of the journal Occupational and Environmental Medicine, reports that night-shift work may be linked to increased ovarian cancer risk.
The Fred Hutch team, led by Dr. Parveen Bhatti, of the Center’s Public Health Sciences Division, found that night shifts were associated with a 24 percent increased risk of invasive epithelial ovarian cancer and a 48 percent increased risk of borderline disease compared with those who only worked daytime hours. They also found that women ages 50 and above were significantly more likely to develop ovarian cancer if they had worked at night.
No wonder the International Agency for Research on Cancer classifies shift work that disrupts circadian rhythms (the body’s normal time clock) as a cancer-causing agent.
What is causing this increased risk? Bhatti and his co-authors, Drs. Mary Anne Rossing and Kristine Wicklund, speculate the increased risk could be linked to melatonin, a powerful hormone that is normally produced at night. Melatonin regulates reproductive hormones, including estrogen, and it scavenges harmful free radicals and boosts production of other antioxidants in the body. However, melatonin production is suppressed by ambient light.
Expect to hear more in the near future about melatonin, late-night shifts and increased risk of cancer. For now, getting a good night’s sleep can’t hurt at all. If anything, it might just keep those grumpy feelings from bubbling to the surface—and that potential extra weight at bay.