人体过度的体力和脑力劳动，会产生疲劳，机体感觉迟 钝，动作缓慢，工作效率下降。这是一种生理现象，经过适当的休息，疲劳会消除。但是，过度的疲劳，指超负荷的劳动和长时期的疲劳得不到充分的休息，将有害于身体的健康发展，降低的机能将不可能恢复。例如听觉器官长期处于 Excessive human physical and mental work, will produce fatigue, the body feel insensitive, slow movements, work efficiency decline. This is a physiological phenomenon, after proper rest, fatigue will be eliminated. However, excessive fatigue means that overloaded work and long-term fatigue do not get enough rest, which will be detrimental to the healthy development of the body and the reduced function will not be restored. For example, hearing organs are long-term