Sleeping in the middle of the night dry mouth may be physiological factors (diet, environment), pathological factors (cold and fever, dry syndrome, hyperthyroidism, adenoid hypertrophy, etc.). 1. Physiological factors: (1) Dietary factors: the food eaten at dinner is more salty, or a large amount of alcohol intake of less water, so sleep in the middle of the night dry mouth. (2) Environmental factors: indoor stuffy, not open the windows to ventilate, sweat more, sleep in the middle of the night dry mouth. 2. Pathological factors: (1) Cold and fever: catching a cold and having a fever can cause dry mouth, nasal congestion, runny nose and other symptoms. (2) Dry syndrome: salivary gland function is abnormal, saliva secretion is relatively small, so dry mouth when sleeping. (3) Hyperthyroidism: the level of thyroxine secretion in the body is too high, and the body’s metabolism is too fast leading to dry mouth and sweating during sleep. (4) Adenoid hypertrophy: Due to adenoid hypertrophy caused by poor breathing, open mouth breathing, so feel dry mouth in the middle of the night. Sleeping in the middle of the night, dry mouth, involving more reasons, it is recommended to consult a doctor in a timely manner to identify the cause of the disease and follow the doctor’s instructions for treatment.