Fibromyalgia is a poorly understood condition that causes multiple tender points, called trigger points, in the muscles and soft tissues of the body.

What is going on in the body?

People who have fibromyalgia have chronic, widespread pain and stiffness in the muscles. Fatigue is a key factor in fibromyalgia. Some healthcare professionals believe that fatigue may occur because the person doesn't get enough deep, restful sleep. Others believe that the sleep disturbance may actually be a cause of the fibromyalgia.

Recent research has shown that people who have fibromyalgia have a decrease in blood flow to the parts of the brain involved with pain perception. They also have two times the normal level of a brain chemical known as substance P. This substance is involved in the transmission of pain messages from nerve cells to the brain.

Fibromyalgia may occur alone, or together with other disorders such as Lyme disease or rheumatoid arthritis.

What are the causes and risks of the condition?

No one knows for sure what causes fibromyalgia, but there are several theories. Some possible causes of fibromyalgia include the following:

New research findings suggest that autoimmune disorders may be triggered by a transfer of cells between the fetus and the mother during pregnancy. The study involved women with scleroderma, an autoimmune disorder involving the skin. These women have more fetal cells in their blood decades after a pregnancy than women who don't have scleroderma. While further research is needed to substantiate these findings, the study does offer an explanation for the much higher incidence of autoimmune disorders in women than in men.

Women account for 75% of those who have the disease. It is most common in women of childbearing age.