Fibromyalgia is a common condition characterized by long-term, body-wide pain and tender points in joints, muscles, tendons, and other soft tissues. Fibromyalgia has also been linked to fatigue, morning stiffness, sleep problems, headaches, numbness in hands and feet, depression, and anxiety.

Fibromyalgia can develop on its own or along with other musculoskeletal conditions such as rheumatoid arthritis or lupus.

The cause of this disorder is unknown. Physical or emotional trauma may play a role in development of the syndrome. Some evidence suggests that fibromyalgia patients have abnormal pain transmission responses.

It has been suggested that sleep disturbances, which are common in fibromyalgia patients, may actually cause the condition. Another theory suggests that the disorder may be associated with changes in skeletal muscle metabolism, possibly caused by decreased blood flow, which could cause chronic fatigue and weakness.

Others have suggested that an infectious microbe, such as a virus, triggers the illness. At this point, no such virus or microbe has been identified.

Pilot studies have shown a possible inherited tendency toward the disease, though evidence is very preliminary.

Men and women of all ages get fibromyalgia, but the disorder is most common among women aged 20 to 50.