Causing snot to flow into the throat while sleeping is a postnasal drip syndrome, which often occurs with conditions such as rhinitis-sinusitis. Many diseases can cause postnasal drip, including seasonal allergic rhinitis, perennial allergic rhinitis, perennial non-allergic rhinitis, vasomotor rhinitis, post-infectious rhinitis, and chronic sinusitis. Due to the inflammatory reaction of the nasal mucosa, congestion and edema phenomenon, mucus gland secretion increases, and a large amount of nasal snot in the nasal cavity flows to the throat area during sleep due to the change of body position, and the phenomenon of backflow of nasal snot occurs. The most common manifestations of postnasal drip syndrome are the sensation of a foreign body dripping into the throat, the need to clear the throat, an itchy throat, nasal congestion and runny nose. There are other reasons for the symptoms of sleeping with snot flowing into the throat, and it is recommended to seek medical attention in time to identify the cause and give targeted treatment, so as not to miss the condition.