Nosebleed on the left side every morning may be caused by dry environment, deviated septum and high blood pressure. 1. Dry environment: If the environment in which you sleep at night is dry, it is easy to increase the fragility of the skin and blood vessels. Nasal mucosa is very dry, and in the morning when the difference between the nasal cavity and the ambient temperature is large causing vasoconstriction, it may lead to vascular brittleness, and the phenomenon of nosebleed on the left side of the nose every morning. 2. Nasal septum deviation: Nasal septum deviation site will appear vascular deformity, and the mucous membrane is also very thin, at the same time the nasal blood supply is very rich. When the mucous membrane of the protruding part is cracked, there may be nosebleeds on the left side of the nose every morning. 3. Hypertension: In hypertension, due to high arterial pressure, the walls of blood vessels become thin and less elastic. When the blood pressure fluctuates greatly in the morning, the blood vessels are easy to rupture, which is manifested as nosebleed, thus the phenomenon of nosebleed in the left side every morning. In addition, obstructive anemia, nasal tumors and so on may lead to nosebleed in the morning. Patients should go to regular hospitals in time to find out the cause of the disease and choose targeted treatment.