Sleeping at night without coughing but coughing during the day, mainly common in the respiratory system has an inflammatory response, airway congestion, edema and a large number of inflammatory secretions exudate. Because at night when you sleep, the human body is in a relatively quiet state, heart rate and respiration are relatively slower than during the day, the whole body belongs to the state of relaxation, this time the bronchial smooth muscle of the airway is a state of relaxation, and the airway channel is relatively smooth. Cough during the day is due to the human body in the daytime is relatively awake, excited state, the inflammatory response of the respiratory tract is active, will continue to secrete a large amount of inflammatory secretions, airway congestion, edema state is relatively more obvious than at night, so it will stimulate the airway cough, the more common is bronchitis, pneumonia, lung abscess and so on.