Chronic fatigue syndrome is the common name for a group of significantly debilitating medical conditions characterized by persistent fatigue and other specific symptoms that lasts for a minimum of six months in adults . The fatigue is not due to exertion, not significantly relieved by rest, and is not caused by other medical conditions. CFS may also be referred to as myalgic encephalomyelitis , post-viral fatigue syndrome , chronic fatigue immune dysfunction syndrome , or by several other terms. Biological, genetic, infectious and psychological mechanisms have been proposed, but the etiology of CFS is not understood and it may have multiple causes.