The child always says tired, the following common situations: 1, psychological factors, because parents often talk about tired, and the baby can not express correctly, when the mood is low or physical discomfort is also easy to imitate adults say tired, when given rest or distraction, will immediately disappear. 2, low muscle strength of both lower limbs, when there is low muscle strength, walking for a period of time, the lower limbs weight-bearing strain, easy to talk about tired, need to go to the children’s 3. Viral myositis or progressive myasthenia gravis, children with a history of acute upper respiratory tract infection before the onset of the disease, will show progressive aggravation or even regression with the passage of time, and need to go to the hospital in a timely manner.