Review of clinical and psychobiological dimensions of the chronic fatigue syndrome: differentiation from depression and contribution of sleep dysfunctions.

Chronic fatigue syndrome (CFS) is a disabling condition characterized by subjective fatigue, mental and physical fatigability, a whole range of somatic symptoms and a poor quality of sleep. Its physiopathology is largely unknown. Several clinical and biological differences were observed between CFS and major depression. A classical conceptualization of masked (or somatized expression of) depression is therefore no longer tenable. Sleep anomalies were reported in all studies published to date. However, these sleep anomalies do not seem to explain a major part of the symptomatology of CFS. The contribution of sleep abnormalities to the development and chronicity of CFS should be further studied. CFS can be considered as a somatoform condition. CFS is like most functional disorders a clinically and biologically heterogeneous condition. The best available treatment to date is cognitive-behavioural therapy.