These issues have led to significant controversy over the definition and the diagnostic criteria of fibromyalgia. They can be encountered in other disorders that may overlap with fibromyalgia, often without having clear boundaries, while their nature makes them difficult to be objectively defined and quantified. These symptoms are relatively common and non-specific.
Fibromyalgia is a clinical entity characterized by the combination of chronic widespread pain and other non-pain related symptoms, including fatigue, poor sleep and cognitive disturbances, which can exhibit significant variation not only between different patients, but also in the same patient during the course of the disease.
