The common causes of nosebleeds in the middle of the night are: environmental factors, allergic rhinitis, deviated septum and so on. 1. Environmental factors: If the air in the bedroom where the child sleeps is dry, too hot, low air pressure, room temperature is too high, at this time, the mucous membrane of the nasal cavity will be very easy to dry, become fragile, and may appear in the middle of the night nosebleed. 2. Allergic rhinitis: If the child is allergic to mites and there are mite allergens in the bed, it will cause allergic rhinitis attacks, leading to symptoms of nasal itching, resulting in an increase in the frequency of rubbing the nose, which in turn will cause the child to have a nosebleed in the middle of the night. 3. Nasal septum deviation: it can lead to vascular deformity of the nasal mucosa here, and the mucosa of the deviated part is relatively thin and sensitive, which is more susceptible to the influence of external factors, resulting in the performance of breakage and bleeding, and so it will also lead to the patient’s nosebleed in the middle of the night. In conclusion, nosebleeds in the middle of the night in children can be caused by physiological or pathological reasons, if there are uncomfortable symptoms, it is recommended to consult a doctor in time.