Reasons for not coughing during the day but coughing at night: I. When you sleep at night, because your body is lying flat, the abdominal organs and diaphragm are elevated, which can lead to restricted lung diastole, so the coughing symptoms are more severe at night than during the day. Second, the lungs have to be detoxified at night, and coughing clears the throat and bronchial foreign bodies, which is also a way for the body to detoxify itself. And 3-5 a.m. is the best time to detoxify the lungs, so when there are symptoms of coughing, the most intense cough for many people will be at this point in time. Third, blood qi runs at night. 1-3 p.m. is when the body’s blood qi runs right up to the lung meridian, when the lungs begin to self-regulate and repair, and a slight cough at this time is normal. However, if there is smoking, the cough will be more powerful at night. If there is inflammation, it is recommended to take oral anti-inflammatory drugs or cough suppressants. If there is phlegm, it is important to take medication to reduce phlegm.