This paper hypothesises that CFS happens after low dose radiation. http://www.ncf-net.org/radiation/LoganovskyLowDoseIonizingRadiationBrain.pdf (A quote from near the end) "A hypothesis about the development of Chronic Fatigue Syndrome (CFS) under the impact of low and very low doses combined with psychological stress has been suggested. CFS can be considered to be an environmentally induced predisposition and vestige of forthcoming neurodegeneration, cognitive impairment, and neuropsychiatric disorders (Loganovsky 2000, 2003; Volovik, Loganovsky, & Bazyka, 2005; Volovik, Loganovsky, Bazyka, Bebeshko, Cohen, Chao, et al., 2006). Moreover, CFS and metabolic syndrome X are considered to be both radiation-associated syndromes and stages of other neuropsychiatric and physical pathology developments, and CFS can be transformed into metabolic syndrome X. Radiation-induced damage of mitochondrial DNA in post-mitotic tissues with low proliferation activity may be a basis for the effects of low doses in an increase of non-cancer morbidity and mortality in the Chernobyl accident survivors (Kovalenko & Loganovsky, 2001). Currently, post-radiation syndrome is proposed to be CFS or a chronic fatigue syndromelike illness, initiated by exposure to ionizing radiation. The symptoms and signs of post-radiation syndrome and its chronicity are similar or identical to those of CFS and can be explained as being a consequence of nitric oxide/peroxynitrite cycle etiology (Pall, 2008)."