Fibromyalgia pain, meaning muscle and connective tissue pain, is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. Fibromyalgia symptoms are not restricted to pain, leading to the use of the alternative term fibromyalgia syndrome for the condition. Other symptoms include debilitating fatigue, sleep disturbance, and joint stiffness. Some patients may also report difficulty with swallowing, bowel and bladder abnormalities, numbness and tingling, and cognitive dysfunction. Fibromyalgia is frequently combid with psychiatric conditions such as depression and anxiety and stress-related disorders such as posttraumatic stress disorder. Not all people with fibromyalgia experience all associated symptoms. Fibromyalgia is estimated to affect 2–4% of the population, with a female to male incidence ratio of approximately 9:1. Evidence from research conducted in the last three decades has revealed abnormalities within the central nervous system affecting brain regions that may be linked both to clinical symptoms and research phenomena. These studies show a correlation, but not causation. Some research suggests that alterations in the central nervous system might be the result of childhood stress, or prolonged or severe stress. Historically, fibromyalgia has been considered either a musculoskeletal disease or neuropsychiatric condition. Although fibromyalgia has no cure yet, some treatments demonstrated by controlled clinical trials have been effective in reducing symptoms, including medications, behavioral interventions, patient education, and exercise. The most recent approach of a diagnosis of fibromyalgia involves pain index and a measure of key symptoms and severity.