Dry mouth when sleeping, the reasons are as follows: I. Physiological reasons: 1. dietary factors, eating salty food will feel dry mouth, 2. dry air, sleeping with the air conditioner on in the room, no humidification equipment leading to dry air, will feel dry mouth. After these life factors are removed, the feeling of dry mouth will usually disappear; 2, pathological reasons: 1, obesity, patients sleep at night snoring, open mouth breathing, will lead to more water evaporation from the oral mucosa, will feel dry mouth when waking up, these patients snoring is more obvious, 2, diabetes, patients will drink water all day and night, dry mouth is more obvious, someone to the night may be particularly obvious, and will be accompanied by increased urine volume, 3, urolithiasis, patients with dry mouth feeling will be more obvious, drinking water may be 10-20 pounds per day. In short, if there is always a dry mouth at night, and exclude environmental and dietary factors, it is recommended to go to the hospital for further examination.