http://www.slate.com/articles/health_and_science/medical_examiner/2015/11/chronic_fatigue_pace_trial_is_flawed_should_be_reanalyzed.html

Last month, a team of researchers released their latest study on chronic fatigue syndrome. Psychotherapy and a gradual increase in exercise, the researchers claimed, were lasting, effective treatments that could lead to recovery. The study was an update of the largest treatment trial in CFS history, now with longer-term data.

http://www.cdc.gov/cfs/

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. Symptoms affect several body systems and may include weakness, muscle pain, impaired memory and/or mental concentration, and insomnia, which can result in reduced participation in daily activities.

https://en.wikipedia.org/wiki/Chronic_fatigue_syndrome

Chronic fatigue syndrome (CFS) is a medical condition characterized by long-term fatigue and other symptoms that limit a persons ability to carry out ordinary daily activities.[2][3][3] Quality of life of persons with CFS can be compromised.