Chronic fatigue is a lack of energy that a person feels not only while doing something, but also in a state of rest. It's a chronic lack of energy with which the day begins. In such a state, the immunity is lower, as can be seen through frequent infections of the respiratory and urinary tract. Chronic fatigue is, most often, a state without physical illness, in which an organism can not fulfill everyday tasks, which it previously did without difficulty. It is gradual and lasts for a long time.