Fatigue is usually associated with physical or mental weakness. Mental fatigue can display itself as somnolence, or as a decrease of attention and reduced level of consciousness, not necessarily including sleepiness.
Fatigue is different from nap, where a person feels that sleep is required. People suffering from mental fatigue feel tired and exhausted all day long. Affecting both body and mind fatigue can make even the simplest of life’s responsibilities difficult to manage with.
Mental fatigue is a normal response to continual mental effort, stress, depression, and deficit of sleep but can be a sign of a physical disorder as well. Also there are may be other causes, such as vitamin deficiencies.
Mental fatigue is a state where the brain cells become exhausted due to brain over-activity just as our bodies do when we've been over trained.
At the end of the working day some people get tired, they lower concentration and make mistakes that mean signs of mental fatigue. Also, mental fatigue can result from such factors as being overworked, constantly worried or stressed out. Late nights spent working or studying can lead to mental fatigue, making difficult to concentrate and resulting in mistakes and lapses.
Generally, every mental process going into overload can cause of mental fatigue. An essential contributor to mental fatigue can be disrupted sleep, so diagnostics evaluates the quality of sleep, the emotional state of the individual and stress level.