Once lying down on the nasal congestion, mainly and its own anatomical structure, cause the corresponding symptoms of the causes mainly include chronic simple rhinitis, soft palate fall, adenoid hypertrophy, posterior nostril polyp, nasopharyngeal fibroangioma, and so on. 1. Chronic simple rhinitis: the hypertrophy of the nasal turbinate, good blood circulation during normal activities, will not cause obvious nasal congestion, once lying down, the blood circulation in the nose will be abnormal, which will further lead to congestion of the nasal turbinate, increase in size and aggravation, thus blocking the airway and causing related symptoms. 2. Soft palate falling back: some people have small pharyngeal cavity development or soft palate hypertrophy, when lying down, the soft palate will fall down and block to the posterior nasal passage, causing related symptoms. 3. Adenoid hypertrophy: Adenoid hypertrophy, after lying down, will easily cause the airway to become narrower and aggravated, which will further lead to the performance of nasal congestion. 4. Posterior nostril polyp: after lying down, the posterior nostril polyp, because of the polyp sagging, further causing nasal passage blockage, causing symptoms of nasal congestion. 5. Nasopharyngeal fibrous hemangioma: the corresponding lesion is rich in blood supply, after lying down, with the change of circulatory status will cause congestion, will also cause airway obstruction, causing nasal congestion symptoms. If there is obvious nasal congestion accompanied by bloody snot and other symptoms, it is necessary to consult a doctor in time for observation, and carry out standardized treatment under the guidance of clinicians after diagnosis of the disease, so as to avoid the delay of the disease.