There are many reasons for coughing while lying down at night, such as cardiac insufficiency, gastroesophageal reflux disease and cough variant asthma. 1. Cardiac insufficiency: cardiac insufficiency can cause patients to cough when lying down because of the sudden increase in the volume of return blood, the heart load increases, aggravating the lungs, and coughing, often accompanied by chest tightness, and even dyspnea. 2. Gastroesophageal Reflux Disease (GERD): When lying down, acidic reflux may reflux into the throat, irritating the throat and trachea, causing nighttime coughing, pharyngeal discomfort and other symptoms. 3. Cough variant asthma: a special type of asthma, mainly manifested as irritating dry cough, mostly at night and early morning episodes, without obvious wheezing, shortness of breath and other symptoms. There are many reasons for coughing at night while lying down, and it is recommended that patients go to the hospital in a timely manner to clarify the cause of the disease and under the guidance of the doctor for treatment.