There are mainly the following clinical reasons for nasal congestion when lying down: First, when the patient is standing, the congestion of the inferior turbinate is mainly at the lower end of the inferior turbinate due to the effect of gravity, which generally does not block the posterior nostril and nasopharynx, resulting in the patient’s ventilation may still be possible. When the patient lies down, due to the effect of gravity, the congestion at the back end of the inferior turbinate will increase significantly, blocking the posterior nostril and nasopharynx, resulting in poor ventilation and nasal congestion. Secondly, when the patient lies down, the anterior and posterior diameters of the nasopharynx are obviously narrowed due to the collapse of the soft palate. In conclusion, if the patient is always in this situation, it is recommended that the patient go to the ENT clinic to have an electronic nasopharyngoscopy to examine the nasal cavity and the nasopharynx.