At night the tongue is astringent may be due to environmental factors, digestive disorders or diabetes, etc., need to be specifically analyzed. 1. Environmental factors: If the patient has been in a cold and dry environment for a long time, the temperature at night may be lower than during the day, and the prolonged low temperature and insufficiently moist air can easily lead to throat dryness and irritation of the respiratory system, resulting in the emergence of the tongue at night on the astringent situation. 2. Digestive disorders: If the patient adopts an unhealthy diet for a long time, such as often overeating or like to eat spicy and stimulating food, such as chili peppers, it will lead to digestive disorders, coupled with the saliva at night itself will physiologically become thick, it is easy to appear in the evening the tongue is dry. 3. Diabetes: patients at night on the tongue is astringent may also be due to patients with diabetes, coupled with parasympathetic excitation at night leads to a decrease in saliva, which leads to the emergence of the tongue at night astringent situation. The patient may also have excessive drinking, excessive eating, excessive urination, weight loss. There are many other reasons for tongue astringency at night, and it is recommended that patients seek medical attention as soon as they notice similar conditions, and take targeted measures under the guidance of a doctor.