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.

Researchers say it’s unclear exactly why there’s a link between poor sleep and fibromyalgia. “Previous experimental studies have shown that sleep deprivation is associated with lowered pain-pressure threshold at multiple body sites –symptoms similar to fibromyalgia,” says Mork. Sleep deprivation has also been associated with elevated blood levels of inflammatory markers and a diminished ability for the body to reduce pain, he adds. “It is therefore plausible that long-lasting sleep problems increase the risk of developing widespread chronic pain. It is also possible that sleep problems and pain occur together, inducing a vicious circle where poor sleep causes pain, and pain causes a worsening of sleep quality.”

It remains to be seen if fixing sleep problems will improve fibromyalgia symptoms. “I am not aware of any study that has investigated whether successful treatment of sleep problems in patients with fibromyalgia is associated with improvement of other symptoms such as pain,” Mork says. “I think the key message is that sleep problems should be taken seriously at an early stage to reduce the risk of future development of fibromyalgia.”

Other experts also hope the findings can be used to help patients. “We have known for years that many people with fibromyalgia report sleep problems, but we’ve not had much information with regard to the relationship between the two,” says James K. Walsh, PhD, executive director and senior scientist at the Sleep Medicine and Research Center at St. Luke's Hospital in Chesterfield, Mo. “I think it’s a very solid, well conducted study. It’s interesting. It’s in an area that most of us have been at a loss to figure out why people with fibromyalgia have sleep problems. What is that link? This gives us some insight into possible future research that might ultimately have a clinical benefit.”

However, Walsh adds, “It would be incorrect to conclude from this paper that sleep problems cause fibromyalgia. Sleep problems precede fibromyalgia, but the two things may possibly both be connected to a third thing, another behavioral or environmental problem.”

Walsh says this new data offers a reason to pursue further studies in this area to see whether or not treatment of sleep problems can reduce the risk of developing fibromyalgia. “I think it gives us a pathway to some more precise research that may ultimately [reduce] the risk of fibromyalgia,” Walsh says.