Mental fatigue can affect people for both short and long periods of time. The result of brain cells become exhausted — much like our bodies do when we’ve been physically over-active.
Mental fatigue can be caused by continual mental effort and attention on particular task, as well as high levels of stress or emotion. Basically, any mental process that goes into overload can result in this disorder. A lot of people start to show signs of mental fatigue later in the working day… tasks seem much more complicated, concentration is low, and mistakes are made. Likewise, late nights spent working or studying can cause mental fatigue, making information difficult to recollect and resulting in mistakes and clumsiness.