ABSTRACT
The term mental fatigue is used with different meanings. Mental fatigue is considered as a decrease in physical and cognitive performance. It is considered also as a condition affecting the mental processes, including feelings of fatigue. Ergonomists lay stress on consequences of fatigue. It is work decrement. Very often mental fatigue is viewed in a context of activation theory. According to this workers perform best at some optimum level of activation. If a worker is overloaded, he/she suffers from an exhaustive form of fatigue. In the case of insufficient demands the (load) worker suffers from a type of fatigue known as boredom or monotony.
