Fatigue can be a side effect of many other diseases, but with Chronic Fatigue Syndrome (CFS), it is typically the primary symptom of this potentially debilitating condition that continues to baffle doctors and patients alike.

Like many diseases that tend to affect women in greater numbers than men, CFS, now more formally known as Myalgic Encephalomyelitis (ME) or systemic exertion intolerance disease (SEID), began its introduction into medicine with much skepticism. Its lack of an easily identifiable underlying cause has created a lot of controversy among the scientific community as to whether it is even a real disease.