Previously attributed to genetics, infections, and emotional or physical trauma, scientists now believe fibromyalgia is caused by disruptions in the sleep cycle, U.S. News and World Report reported.

Fibromyalgia is a chronic musculoskeletal condition that affects approximately 5 million adults, 90 percent of which are women. It is characterized by an achy pain, especially when pressure is applied to tender spots on the body.

A new study, conducted by researchers at the Norwegian University of Science and Technology, found that 2.6 percent of women who previously had no musculoskeletal pain or movement disorders - but experienced significant sleep difficulties - developed fibromyalgia within a 10-year span.

The study also said that there is an increased risk for older women. The relative risk increased 2.4 percent for participants over the age of 45.

"Our findings indicate a strong association between sleep disturbance and fibromyalgia risk in adult women," said Dr. Paul Mork, from the Norwegian University of Science and Technology. "We found a dose-response relation, where women who often reported sleep problems had a greater risk of fibromyalgia than those who never experienced sleep problems."

The study was published online in the journal Arthritis and Rheumatism.

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