http://www.cdc.gov/cfs/cfsbasicfacts.htm
Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
Chronic fatigue syndrome, or CFS, is a debilitating and complex disorder characterized by profound fatigue that is not improved by bed rest and that may be worsened by physical or mental activity. This fact sheet provides basic facts on CFS, including prevalence, risk factors, diagnosis, treatment, possible causes, and more.