12/27/11 The exact causes of fibromyalgia remain a mystery, but a new study offers a possible contributing factor: Norwegian researchers found women who have persistent sleep problems are as much as five times more likely to develop fibromyalgia than women without sleep issues.

“Fibromyalgia has been associated with sleep problems in cross-sectional studies. However, no previous studies have investigated whether sleep problems among healthy women increase the risk of future development of fibromyalgia. Our findings are important because they indicate that sleep problems can be an important factor in the development of fibromyalgia,” according to Paul J. Mork, PhD, the study’s principle investigator. “Sleep problems should therefore be taken seriously. Early detection and proper treatment may decrease the risk of fibromyalgia as well as other chronic diseases,” adds Mork, associate professor in the department of Human Movement Science at the Norwegian University of Science and Technology in Trondheim, Norway.

Fibromyalgia, a chronic condition that causes muscle pain and fatigue, among other symptoms, affects about 5 million people – 80 to 90 percent of them women – in the United States, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Insomnia and middle-of-the-night awakenings are common complaints among those with the condition. Still, the link was stronger than researchers expected.

“We were somewhat surprised that the association between sleep problems and risk of fibromyalgia was that strong – more than five-fold increase in risk among middle-aged and older women, even after adjusting our risk estimates for several potential confounding factors that may interfere with sleep like age, exercise, body mass index, psychological well-being and smoking,” Mork says.

For this study, which was recently published online in Arthritis & Rheumatism, researchers identified 12,350 women older than 20 who had no musculoskeletal pain or movement disorders and followed them for 10 years with self-reported questionnaires and physical exams.

After 10 years, 2.6 percent of the study group – 327 women – had developed fibromyalgia. Women older than 45 at the start of the study who said they “always” or “often” had difficulty sleeping were five times more likely within the 10 years to develop fibromyalgia than women in the same age group without sleep problems. Among women aged 20 to 44, those with sleep problems had an almost three-fold risk of developing fibromyalgia compared with those without. Overall, across both age groups, sleep problems more than tripled the risk of developing fibromyalgia.