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NEW YORK (Reuters Health) - Rotating shift work can wreak havoc with bodily functions such as sleep and bowel movements. Now study findings hint that rotating work schedules may also increase risk for irritable bowel syndrome.
Symptoms of irritable bowel syndrome (IBS) include constipation and diarrhea, abdominal pain, cramping, and bloating. It's unclear what causes the syndrome, which affects as many as one in five Americans, according to the National Institutes of Health.
Shift workers often report altered bowel habits similar to people with IBS, Dr. Willemijntje A. Hoogerwerf, at the University of Michigan in Ann Arbor, and colleagues note in the American Journal of Gastroenterology.
Their evaluation of bowel disorders among 399 nurses implies that rotating work schedules, which commonly disrupt the intestinal tract's rhythm, are "associated with a greater chance of having irritable bowel syndrome," Hoogerwerf said in an email to Reuters Health.
She and colleagues assessed self-reported bowel disorders and sleep quality among mostly female nurses with no other conditions potentially associated with bowel dysfunction.
A total of 214 worked straight days, 110 worked straight nights, and 75 rotated between day and night shifts. Generally those working night and rotating shifts were younger, while day shift nurses tended to have longer work experience - nearly 20 years versus 11 to 13 years.
Overall, 36 (48 percent) working rotating shifts reported symptoms of IBS, as did 44 (40 percent) of those working straight nights.
By comparison, 66 (about 31 percent) working straight days had IBS symptoms - still more than what might be expected in the general population (up to about 20 percent).
The investigators found reports of sleeping badly, having trouble falling asleep, and daytime sleepiness all more common among nurses with IBS, regardless of their work shift.
But working a rotating shift remained significantly associated with IBS even after taking into account sleep quality, age, gender, years of experience, and number of years working night or rotating shifts.
Nurses working night and rotating shifts were also more likely to report abdominal pain or discomfort than their day-working peers.
Based on these results, Hoogerwerf questions whether IBS results from "an underlying biological rhythm disorder of the intestine." She and her colleagues call for further studies to assess this.
Meanwhile, Hoogerwerf recommends shift workers with IBS-like symptoms consult their physician "to discuss the potential impact" their work schedule has on their symptoms.
SOURCE: American Journal of Gastroenterology, published online February 16, 2010.