An unjustified feeling of fatigue that lasts for more than six months and is accompanied by cold-like symptoms such as sore throat, enlarged lymph nodes, headaches, muscle/joint pain, impaired memory and concentration, excessive sleepiness, insomnia - may be the basis for the diagnosis of a condition called Chronic Fatigue Syndrome -CFS (Chronic Fatique Syndrome). CSF syndrome was defined as a disease entity in 1988 by the US Center for Disease Control.