Dry mouth in the middle of the night is not necessarily the early stage of cancer, it may be caused by physiological or pathological factors, such as eating too salty food at dinner or hot weather, it may also be caused by diabetes mellitus, hyperthyroidism or dryness syndrome and other diseases, you should seek medical attention to let the doctor to make a clear diagnosis in a timely manner. Eating too salty food at dinner or drinking too much alcohol at night, or hot weather and other physiological factors can lead to dry mouth in the middle of the night, avoid eating too salty food at night, and keep the room ventilated when sleeping can be relieved. Diabetic patients due to increased osmotic pressure in the body, easy to appear in the middle of the night dry mouth; hyperthyroidism patients due to excessive secretion of thyroid hormones, resulting in accelerated metabolism, sleep at night easy to sweat and sweat too much, thus causing dry mouth in the middle of the night; patients with dry syndrome due to excessive loss of water in the mouth and lead to dry mouth. In addition, dry mouth in the middle of the night may also be the early stage of cancer, such as oral cancer and kidney cancer. Oral cancer patients have dry mouth in the middle of the night due to the abnormal function of salivary glands in the oral cavity, which leads to the decrease of saliva secretion; kidney cancer patients have dry mouth in the middle of the night due to the disease affecting the kidney’s filtration function of water, which causes too much water discharge. Therefore, if patients have dry mouth in the middle of the night and fail to get relief by excluding physiological factors, they should go to the hospital in time for consultation, clarification of the cause of the disease, and treatment for the cause.