The other reasons are water intake, air conditioning, heat dissipation in bed, body defense etc.Not knowing enough, it is difficult to give you any advice.Perhaps he see paediatrician.

• 你应该看医生，主要目的是看看医生有没有什麽原因或病在阻碍你的，如果没有，或找不到，可以做的著实不多，还是顺其自然吧。