Definition

Chronic fatigue syndrome (CFS) is a condition that causes extreme tiredness. People with CFS are so tired that they are unable to carry on normal activities for a period of at least six months. They also have other symptoms, such as pain in the joints and muscles, headaches, and sore throat. There is no single known cause for CFS; it appears to result from a number of factors.

Description

Chronic fatigue syndrome is known by many different names. These names include chronic fatigue and immune disorder (CFIDS), myalgic encephalomyelitis (pronounced my-AL-jik en-SEF-uh-lo-MY-uh-LY-tiss), low natural killer cell disease, post-viral syndrome, Epstein-Barr disease, and Yuppie flu. Such names suggest a number of possible causes for CFS. Researchers have not been able to find out which of these causes, or which combination of factors, is responsible for the disease.

Reports of a CFS-like disease date back...