Feeling phlegm in the throat while sleeping in the middle of the night is mostly caused by inflammation of the respiratory tract, such as inflammation of the pharynx, bronchitis, and pneumonia, which can be caused, and is also easily accompanied by fever, cough, sore throat and other symptoms, and needs to be treated with medicines to relieve cough and resolve phlegm. If there is yellow sputum also need to consider is due to bacterial infection, need to use effective antibacterial drugs to treat, also need to use heat to remove fire drugs. If there is no cough, it may also be caused by sinusitis or rhinitis. During sleep, the nasal mucus may go down the nasopharynx into the throat, and you may feel phlegm in the throat, which may also cause headache and nasal congestion.