Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a condition causing persistent fatigue that lasts for at least 6 months (or longer) and isn't due to another medical condition (e.g., hypothyroidism). It was once thought to affect only highly educated young adults who are "high achievers" or career-oriented professionals. It is now known that ME/CFS affects people of all ages and from all walks of life.
ME/CFS is about 2 to 4 times more common in women than in men. It is associated with extreme and prolonged fatigue that isn't relieved by rest. People with ME/CFS experience persistent tiredness so severe that it may prevent them from working, exercising, and enjoying life. ME/CFS is a poorly understood condition and there is no clear consensus about its diagnosis and treatment.
ME/CFS is also known as myalgic encephalomyelitis (ME) or chronic fatigue immune dysfunction syndrome (CFIDS).