Although chronic fatigue in UK adult primary care patients is relatively common,1 there have been no comparative studies in children. Estimates of the prevalence of chronic fatigue syndrome (CFS) or CFS-like illness in children vary widely according to case definition and methodology and range from 2.7/100 0002 to 570/ 100 000,3 although they all suggest that the prevalence is lower than among adults.1
You can read the rest of this article here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1720362/pdf/v090p00367.pdf
Source: Haines LC, Saidi G, Cooke RW. Prevalence of severe fatigue in primary care. Arch Dis Child. 2005 Apr;90(4):367-8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1720362/pdf/v090p00367.pdf (Full article)