At night the tongue is astringent may be due to environmental factors, dietary habits or get dry syndrome, etc., need to be specifically analyzed. 1. Environmental factors: if the patient is in a dry environment such as dry cold winter, the night temperature is lower than the daytime, long-term air conditioning warm air is easy to stimulate the respiratory system, easy to appear at night on the tongue astringent situation. 2. Dietary factors: if the patient likes to eat spicy and stimulating food for a long time, such as chili peppers, etc., it will lead to the body’s sympathetic nerve excitation, reduce the secretion of the glands, at this time due to the increase in respiratory frequency leads to dry mouth, which can lead to tongue dryness in severe cases. 3. Dry Syndrome: The patient’s tongue is astringent at night, which may also be due to dry syndrome. Dry syndrome is a chronic inflammatory autoimmune disease mainly characterized by a decrease in the secretion of lacrimal and salivary glands, so if you suffer from this disease, the patient in addition to the tongue at night, there may also be symptoms of dry eyes. There are many other causes of tongue astringency at night, and it is recommended that patients seek medical attention as soon as they notice a similar condition, and take targeted measures under the guidance of a doctor.