Coughing while lying down is usually caused by gastroesophageal reflux (GERD), cardiac insufficiency or lung disease, and requires prompt medical treatment. 1. Gastroesophageal Reflux Disease (GERD): When the patient lies down, it is easier to cause gastric reflux, which in turn leads to increased coughing. 2. Cardiac insufficiency: the amount of blood returning to the heart will increase when the patient lies down, which will cause the situation of cardiac insufficiency to be more serious, and ultimately cause pulmonary stasis to cause coughing to be more obvious. 3. Lung disease: bronchial inflammation, cough variant asthma, pleural effusion or foreign body and other lung disease patients, different positions may cause bronchial irritation aggravation, causing cough more severe. When lying down coughing significantly, it is recommended that timely medical care, improve the examination, clear cause after targeted treatment.