Waking up at night with white phlegm in the throat may be caused by acute upper respiratory tract infection, chronic pharyngitis, bronchitis and other reasons. 1. Acute upper respiratory tract infection: If the cold stimulates and triggers an acute upper respiratory tract infection while sleeping, it may cause waking up at night with white phlegm in the throat, which may be accompanied by coughing, runny nose, fever and other symptoms. 2. Chronic pharyngitis: due to the presence of inflammatory reactions in the throat area, stimulated by inflammatory products, can lead to increased secretions in the throat area, which may result in waking up with white phlegm in the throat at night, but also accompanied by itching in the throat, dryness, foreign body sensation and other symptoms. 3. Bronchitis: due to the presence of non-specific inflammation of the bronchial mucosa, under the stimulating effect of inflammation, can lead to white phlegm in the throat, especially at night in the lying position under the state of the symptom is more serious, which may result in waking up with white phlegm in the throat at night, but also accompanied by coughing, sniffling, nasal congestion and other symptoms. Waking up at night with white phlegm in the throat may also be caused by other reasons, if the symptoms continue to fail to improve, you should seek medical attention as soon as possible to confirm the diagnosis, and then give targeted treatment.