38 CFR § 4.88a - Chronic fatigue syndrome.
(a) For VA purposes, the diagnosis of chronic fatigue syndrome requires:
(1) new onset of debilitating fatigue severe enough to reduce daily activity to less than 50 percent of the usual level for at least six months; and
(2) the exclusion, by history, physical examination, and laboratory tests, of all other clinical conditions that may produce similar symptoms; and
(3) six or more of the following:
(i) acute onset of the condition,
(ii) low grade fever,
(iii) nonexudative pharyngitis,
(iv) palpable or tender cervical or axillary lymph nodes,
(v) generalized muscle aches or weakness,
(vi) fatigue lasting 24 hours or longer after exercise,
(vii) headaches (of a type, severity, or pattern that is different from headaches in the pre-morbid state),
(viii) migratory joint pains,
(ix) neuropsychologic symptoms,
(x) sleep disturbance.