The Center for Disease Control, or CDC, has established criteria for a diagnosis of chronic fatigue syndrome. First of all, the individual must have a recent history of fatigue. The fatigue must be severe and last, whether constant or not, for at least six months. This fatigue is not relieved by rest. It forces people to reduce their level of activity. Many people describe a sudden onset of fatigue triggered by a physical stress, such as an illness or injury.
At the same time, the person must have at least four of the following eight symptoms for CFS to be diagnosed: