Chronic fatigue syndrom is diagnosed based on a person's symptoms.
Do you have chronic fatigue syndrome? What are the symptoms? Sometimes I feel like I might have it.
No I don't have it, but different agencies and scientific bodies produced different definitions
So what kind of things are they saying defines chronic fatigue syndrome?
There is a variety of conditions rather than a single disease 
Such as? I am sleepy all the time despite sleeping more than 8 hours a day. SOmetimes I feel like too much sleep makes me tired too.
Scientist say that the fatigue is not due to strenuous ongoing exertion, is not much relieved by rest, and is not due to a previous medical condition. 
How can you treat it? Coffe??
The condition is primarily managed rather than cured. I think cognitive behavioral therapy is one of the methods.