Blood in sputum after sleeping may be rhinitis, which may also be related to oral diseases, other respiratory diseases and heart diseases. 1. Rhinitis: It can lead to symptoms of nasal mucosa discharge and bleeding, and the nasal discharge can flow backward into the oropharynx, which in turn leads to the phenomenon of blood in sputum. 2. Oral diseases: such as gingivitis, oral ulcers and other diseases, can lead to pus and blood secretions in the affected area, which in turn leads to blood in sputum. 3. Other respiratory diseases, such as tuberculosis, lung cancer and bronchitis, are also important causes of blood in sputum. 4. Heart diseases: such as heart failure, rheumatic heart disease, some patients may also have symptoms of blood in sputum. The causes of bloody sputum are complex and varied, so it is recommended that patients consult a doctor as soon as possible to confirm the diagnosis and follow the doctor’s instructions to carry out the corresponding treatment in a timely manner.