Waking up in the morning with blackened teeth and tongue may be related to food, medicine or disease. 1. Food: If you eat darker food before going to bed, such as: mulberry, black sesame paste, food containing dark pigment, it is likely to lead to deepening of the color in the mouth the next day, brushing your teeth before going to bed can try to reduce this performance. 2. Drugs: taking some drugs the day before: such as oral iron, licorice tablets and other drugs, it is likely to appear in the mouth blackened, because iron can react with the digestive enzymes in the mouth oxidized black, these are the normal manifestations of the drug, do not have to worry too much. 3. Disease: If the patient suffers from heart disease, it is very likely that the poor circulation caused by bruising, making the color deepen in the mouth. Kidney failure patients can also appear teeth and tongue blackening. Once you wake up in the morning teeth and tongue blackened, you should immediately consult a doctor and under the guidance of the doctor to determine the cause of treatment.