Sudden nosebleed while sleeping at night can be considered as local factors, systemic factors and environmental factors. 1. Local factors: such as nasal diseases such as nasal polyps, nasal sinus inflammation (dry rhinitis), or nasal septum deviation, nasal vascular malformation and other diseases, due to the relative fragility of the nasal blood vessels are easy to rupture, it is more likely to appear the phenomenon of nosebleed. 2. Environmental factors: such as dry weather in the fall leads to dry nasal mucosa, which can easily lead to nasal mucosa cracking and bleeding. 3. Systemic factors: such as coagulation disorders, hypertension, etc., due to elevated blood pressure, nasal blood vessel rupture, and can not be quickly coagulated, there will be nosebleeds. The specific cause of this symptom needs to be determined after specialist consultation and examination. If the nosebleed is more than one, and the pressure and stuffing are ineffective in stopping the bleeding, it is recommended to go to the hospital for treatment in time, so as to avoid hemorrhagic shock caused by excessive blood loss.