In most cases, nosebleeds are caused by environmental factors, trauma, and other blood diseases. 1. Environmental factors: If the air in which a child sleeps at night is too dry, it causes discomfort in the child’s nasal cavity, which leads to rupture and bleeding of the blood vessels of the mucous membrane of the nasal cavity when touched, thus leading to the symptom of children’s nosebleed at night. 2. Trauma: When children play during the day, the nasal cavity is subjected to collision, impact or the presence of foreign objects, so that the nasal cavity becomes fragile, if the child sleeps at night rubbing the nose, which leads to symptoms of nosebleed. 3. Other blood disorders: If a child suffers from blood disorders, such as thrombocytopenia or abnormal coagulation function, the child’s body is more fragile and sensitive when sleeping at night, which can lead to the symptom of nosebleed at night. Nosebleed at night may also be related to other causes, when the symptoms appear, it is recommended to go to the hospital in time for examination, identify the cause of the disease and then treat the symptoms.