What is the cause of coughing at night lying down, most commonly related to gastroesophageal reflux, heart. Under normal circumstances there is a lot of stomach acid in the stomach, in the upright position due to the influence of gravity, not easy to run retrograde from the stomach up to the pharynx, the role of gravity disappears when lying down, patients with gastroesophageal reflux disease, lying down when the stomach acid is easy to retrograde from the stomach to the esophagus, and the pharynx to stimulate the throat. When the left heart insufficiency, due to the patient lying down the sudden increase in the amount of return blood, resulting in cardiac insufficiency symptoms aggravated, mainly manifested as cough, chest tightness, breath-holding and other conditions, and even cause cyanosis, dyspnea and other manifestations, to pay attention to the identification.