For the majority of persons with CFS, work, school, and family activities are significantly reduced for extended periods of time. The severity of symptoms and disability is the same regardless of gender, and many experience strongly disabling chronic pain. Persons report critical reductions in levels of physical activity. Also, a reduction in the complexity of activity has been observed. Reported impairment is comparable to other fatiguing medical conditions including late-stage AIDS, lupus, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), and end-stage kidney disease. CFS affects a persons functional status and well-being more than major medical conditions such as multiple sclerosis, congestive heart failure, or type II diabetes mellitus.Often, courses of remission and relapse of symptoms occur, which make the illness difficult to manage. Persons who feel better for a period may overextend their activities, and the result can be a worsening of their symptoms with a relapse of the illness.About 25% of people with CFS are house-bound or bed-ridden for long periods during their illness, often for decades. : 32  An estimated 75% are unable to work because of their illness. More than half were on disability benefits or temporary sick leave, and less than a fifth worked full-time. Children who become ill with CFS are a major cause of school absence.
: 183 People with CFS have decreased scores on the SF-36 quality-of-life questionnaire, especially in the sub scales on vitality, physical functioning, general health, physical role, and social functioning; however, the sub scales for "role emotional" and mental health in CFS patients were consistent with or not substantially lower than healthy controls. Cognitive functioning
Cognitive dysfunction is one of the more disabling aspects of CFS due to its negative impact on occupational and social functioning. Fifty to eighty percent of persons with CFS are estimated to have serious problems with cognition. Cognitive symptoms are mainly due to deficits in attention, memory, and reaction time. Measured cognitive abilities are found to be below projected normal values and likely to affect day-to-day activities; for example, increases in common mistakes, forgetting scheduled tasks, or having difficulty responding when spoken to are observed.Simple and complex information-processing speed and functions entailing working memory over long time periods are moderately to extensively impaired. These deficits are generally consistent with the patients perceptions. Perceptual abilities, motor speed, language, reasoning, and intelligence do not appear to be significantly altered. When poorer health status was reported, a persons perception of their cognitive problems was frequently greater. Better physical functioning in people with CFS is associated with less visuoperceptual difficulty and fewer language-processing complaints.Inconsistencies of subjective and observed values of cognitive dysfunction reported across multiple studies are likely caused by a number of factors.