Myalgic encephalomyelitis (ME) is characterised by prolonged fatigue associated with a wide range of accompanying symptoms. ME has also been called postviral fatigue syndrome, myalgic encephalomyelitis or chronic fatigue. There's no evidence to support the view that ME is a contagious disease and there's no identified cause, although viral infection, stress and toxins have all been suggested as possible triggers.
It can affect people of any age. However, it's most common between the ages of 25 and 45. It's estimated that around 150,000 people in the UK have ME, with women affected more often than men. To be diagnosed with ME someone must have severe chronic fatigue for at least six months with no other medical condition identified as the cause. They must also have four or more of the following symptoms: