Drooling in sleep is usually not a precursor of cancer, but is mostly due to improper sleeping posture and needs to be analyzed specifically. The phenomenon of frequent drooling after falling asleep is considered to be caused by the following reasons. First, incorrect sleeping posture, such as lying on the side for a long time; second, some patients are troubled by rhinitis and sinusitis, and when breathing, they often choose to use their mouths to assist breathing, resulting in habitual opening of the mouth during sleep; third, if there is one side of the face with limited movement, crooked mouth and eyes, and drooling at the corners of the mouth, it may be related to facial neuritis; fourth, some patients may suffer from oral diseases, such as mouth ulcers, or malignant tumors in the interior, which can also Fourth, some patients due to oral diseases such as oral ulcers, or internal malignant tumors, can also lead to salivation during sleep; Fifth, if salivation during sleep is accompanied by dizziness, headache, numbness of one side of the limbs, or restricted movement and other symptoms, it is usually associated with cerebrovascular disease, and it is recommended that head CT and other tests be performed to address the cause of the disease. It is recommended that patients go to the stomatology, gastroenterology or neurology department of the hospital in time to identify the cause of the disease and then carry out the relevant treatment.