It is estimated that at least one million Americans have chronic fatigue syndrome, though only about 20 percent of cases are diagnosed. The condition is more than simply being tired all the time. Rather, the tiredness is pervasive, not mere sleepiness but a thoroughly worn-out, drained feeling that goes beyond a mere need for sleep. In fact, one diagnostic criterion for chronic fatigue is that sleep doesn’t help, and that the tiredness halves the patients ability to participate in ordinary activities. Other symptoms are loss of concentration, a sore throat, unexplained muscle pain, exhaustion that lasts more than 24 hours, joint pain without swelling that moves around, swollen lymph nodes, and new and unfamiliar headaches.
Despite this formidable list of symptoms, several of which are generally required for a diagnosis, many people—even many doctors—doubt that chronic fatigue syndrome is a real condition. Indeed, some advocates for patients feel that the very name "chronic fatigue syndrome" trivializes the condition and contributes to the the idea that it is a psychosomatic illness; many of these advocates prefer the term myalgic encephalomyelitis or myalgic encephalopathy. Other experts contend that the fact that an illness is psychosomatic doesn’t mean that it’s not real. Even if there is no physical cause of a condition, it can cause real symptoms.
Moreover, some researchers have found evidence for physical causes. At least some cases of chronic fatigue are due to the Epstein-Barr virus, a virus carried by a substantial majority as many as 95 percent of adults but to which most people develop immunity. Epstein-Barr is also the virus behind many cases of mononucleosis. Another virus called HHV-6 shows a similar pattern—infects 95 percent of the population, normally harmless, linked to chronic fatigue.
In addition, acceptance of chronic fatigue syndrome as a genuine illness has been hampered by a inability to see the effects of the condition in the body. Now brain scans using PET technology have found actual differences in the brains of chronic fatigue patients. Compared to healthy people, people with chronic fatigue showed noticeably higher levels of inflammation in the brain. This may help give health care providers an objective, measurable diagnostic criterion, allowing them to better serve their patients.