有不少老年人睡到半夜后，往往会感到口干舌燥，严重的会出现嘴唇干裂或有咽喉燥热感，难以继续入眠，十分苦恼。口干大致分以下几种：生理性起口干症状。白天因说话、进食等口腔运动，唾液尚能不断分泌，因而感觉不到口干。晚上睡眠中，唾液分泌明显减少，就会出现口干现象。 Many elderly people sleep until midnight, often feel dry mouth, severe dry lips or throat may have a sense of heat, it is difficult to continue to sleep, very distressed. Dry mouth roughly divided into the following categories: Physiological dry mouth symptoms. During the day because of speech, eating and other oral exercises, saliva is still able to continue to secrete, and therefore do not feel dry mouth. During sleep at night, saliva secretion decreased significantly, there will be dry mouth phenomenon.