The reasons for sleeping at night with a dry mouth and old drinking water are physiological reasons, food too salty, weather, etc.; pathological reasons such as diabetes, uremia, etc.. 1. Physiological aspects: eating too salty food at dinner, there will be dry mouth and want to drink water, it is recommended to eat a light diet, should not eat too salty food; also related to the hot weather, water evaporation will lead to dry mouth. 2. Pathological aspects: including dry syndrome, diabetes mellitus, uremia, brain injury and other diseases; dry syndrome patients with abnormal secretion of the salivary glands, which can lead to dry mouth; diabetic patients due to elevated blood glucose, will produce a sense of thirst, but not only limited to the night, but also during the day; patients with uremia large loss of water, there will be a sense of thirst; in addition, after the brain injury will be a sense of thirst. It is recommended that patients with pathologic causes actively go to the hospital for treatment.