The term chronic fatigue is generally used when a patient experiences unexplained, persistent fatigue for more than six months.

There are many symptoms including disabling exhaustion, headaches, short-term memory loss, severe inability to concentrate, depression, lack of restful sleep, muscle weakness and lymph node pain.

There seems to be no primary cause of chronic fatigue syndrome, but many experts suspect that there are multiple factors that play a role, such as a hyper-reactive immune system and a viral or other infectious agent.

As it is fairly hard to diagnose chronic fatigue, normally physicians will first rule out as many other possible causes of any exhaustion which has lasted more than six months.

It is very important to recognise that, as well as being difficult to diagnose, chronic fatigue can be difficult to treat with wide variations occuring between patients. Some may experience no discernable difference in their well-being, while others may improve.