Colon has its own biological clock

ANN ARBOR, Mich., March 22 (UPI) -- Shift workers may be more at risk than others for irritable bowel syndrome, U.S. researchers warn.

Researchers at the University of Michigan Medical School in Ann Arbor found abdominal pain more common among nurses working rotating shifts.

The study, published in the American Journal of Gastroenterology, suggests nurses participating in shift work -- particularly those who participate in rotating shift work -- have a higher prevalence of irritable bowel syndrome and abdominal pain. This association was independent of sleep quality.

"We know the colon has its own biological clock and that's what increases the likelihood of having a bowel movement in the first six hours of the day," study lead author Dr. Sandra Hoogerwerf says in a statement. "The question now for further research is if irritable bowel syndrome and abdominal pain is an underlying manifestation of a circadian rhythm disorder."

Hoogerwerf and colleagues evaluated nurses, 85 percent of them women, classified into three groups -- 214 working permanent day shifts, 110 working permanent night shifts and 75 working rotating shifts between day and night. The evaluations were based on self-reported abdominal symptoms and sleep quality.