Fibromyalgia (FM or FMS) is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. It is an example of a diagnosis of exclusion. 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 comorbid 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 24% of the population with a female to male incidence ratio of approximately 9:1. The term “fibromyalgia derives from new Latin, fibro-, meaning “fibrous tissues”, Greek myo-, “muscle”, and Greek algos-, “pain”; thus the term literally means “muscle and connective tissue pain”) The brains of fibromyalgia patients show structural and behavioral differences from those of healthy individuals, but it is unclear whether the brain anomalies cause fibromyalgia symptoms or are the product of an unknown underlying common cause. Some research suggests that these brain anomalies may be the result of childhood stress, or prolonged or severe stress. Historically, fibromyalgia has been considered either a musculoskeletal disease or neuropsychiatric condition. Although there is as yet no cure for fibromyalgia, some treatments have been shown by controlled clinical trials to effectively reduce 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. Fibromyalgia has been recognized as a diagnosable disorder by the US National Institutes of Health and the American College of Rheumatology. Fibromyalgia, a central nervous system disorder, is described as a ‘central sensitization syndrome’ caused by neurobiological abnormalities which act to produce physiological pain and cognitive impairments as well as neuro-psychological symptomatology. Despite this, some medics do not consider fibromyalgia a disease because of a lack of abnormalities on physical examination and the absence of objective diagnostic tests.