The Canadian criteria for ME/CFS will be met if patients exhibit fatigue, post-exertional malaise and/or fatigue, sleep dysfunction, and pain; have two or more neurological/cognitive manifestations and one or more symptoms from two of the categories of autonomic, neuroendocrine and immune manifestations (including confusion, disorientation, short-term memory impairment, ataxia), and the illness must persist for at least 6 months.