Drinking water all the time in the middle of the night can be due to physiological and pathological reasons. Common pathologic causes include diabetes mellitus and uremia. 1. Physiological reasons: for example, eating too salty dinner, bedroom air humidity is too low, will lead to sleep at night always thirsty, and then always drink water. It is recommended to have a light diet in daily life and maintain proper humidity in the living room by using a humidifier. When the daytime work is too tired, too much exercise, and seldom drink water during the day, the amount of liquid supplementation is insufficient, can also lead to always drink water in the middle of the night. 2. Diabetes: Patients with diabetes have a tendency to drink more and urinate more. As the patient’s blood sugar increases, resulting in increased plasma osmotic pressure, which stimulates the thirst center, producing the symptoms of thirst, which in turn leads to always drink water in the middle of the night. 3. Uremia: mainly due to the lack of arginine or the body’s insensitivity to it, it can make the patient appear the manifestation of hypotonic polyuria. Because patients urinate a lot, so it will make the body lack of water, resulting in thirst, which in turn leads to always drink water in the middle of the night. The above are only some of the common causes. In short, always drink water in the middle of the night can be physiological reasons, may also be caused by disease, it is recommended to consult a doctor in a timely manner, a clear diagnosis and comply with the doctor’s instructions for standardized treatment.