The best-known symptom of ME/CFS is fatigue. However, the fatigue of ME/CFS is nothing like the fatigue most people experience at the end of a long day or following a strenuous workout. The Centers for Disease Control (CDC) describes the fatigue of ME/CFS as “severe, incapacitating, and all-encompassing.” In fact, the fatigue people with ME/CFS experience is so severe that it significantly limits their ability to work, go to school, participate in social activities and take care of their own personal needs. The most severe cases can leave patients housebound or bedridden.
A key component of ME/CFS fatigue is post-exertional malaise. This is extreme, prolonged exhaustion and a worsening of symptoms following physical or mental exertion. The symptom exacerbation usually begins 12 to 48 hours after the exertion and requires an extended period of recovery. Other fatigue characteristics ME/CFS patients describe include feeling like they have the flu all the time, a feeling of heaviness in their limbs, and low energy levels accompanied by a feeling of over-stimulation.
Another defining factor of the fatigue of ME/CFS is that it is not relieved by sleep. Patients may awaken feeling just as fatigued as they did before they went to sleep. Because getting good, deep, refreshing sleep is essential for the body to replenish itself, healthcare professionals will often address sleep issues first. If sleep problems can be corrected, fatigue symptoms should begin to improve as well.