Nosebleeds at night can be caused by dry air, allergic rhinitis and blood clotting disorders. 1. Dry air: children’s nasal mucosa is relatively fragile, if the indoor air is too dry when sleeping, it may lead to dry nasal mucosa rupture bleeding, thus causing children to sleep at night nosebleeds. 2. Allergic rhinitis: this disease is common with nasal itching, runny nose, sneezing and other symptoms, night children feel itchy nose, may use the fingers to pick the nose, which may lead to nasal mucous membrane damage, appearing at night when you sleep, the symptoms of nosebleed. 3. Coagulation dysfunction: if the children’s body lacks coagulation factors, it may lead to coagulation dysfunction, which may lead to symptoms of nosebleeds at night. If a child has a nosebleed at night, the amount of blood is relatively large, you should go to the hospital in time, to clarify the cause of the disease, under the guidance of a professional doctor to carry out targeted treatment.