Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that goes away after you rest. Instead, it lasts a long time and limits your ability to do ordinary daily activities.

Symptoms of CFS include fatigue for 6 months or more and experiencing other problems such as muscle pain, memory problems, headaches, pain in multiple joints, sleep problems, sore throat and tender lymph nodes. Since other illnesses can cause similar symptoms, CFS is hard to diagnose.

No one knows what causes CFS. It is most common in women in their 40s and 50s, but anyone can have it. It can last for years. There is no cure for CFS, so the goal of treatment is to improve symptoms. Medicines may treat pain, sleep disorders and other problems.*

Source: U.S. National Library of Medicine