At night, the cough will become severe and frequent, the throat will be itchy, and the cough will not stop, even affecting the sleep of myself and my family. Why does the cough become more serious at night? Physiological research shows that coughing is a reflex defense behavior for self-protection of the respiratory tract. A complete coughing action goes through the following steps: first, inhalation, then closing the glottis, and contracting through the intercostal muscles and diaphragm, producing about 40Kpa. The pressure in the lungs increases, and then the diaphragm contracts rapidly and the glottis suddenly opens. The gas in the lungs rushes out of the respiratory tract, and the secretions or foreign matter adhered to the respiratory mucosa are ejected, eventually forming a coughing action. These complex and coordinated movements are caused by stimulating nerve ending receptors to generate impulses. The afferent nerves excite the respiratory center in the medulla oblongata, and then the respiratory center sends out impulses. The efferent nerves act on the intercostal muscles, diaphragm, glottis, etc. to erupt. In coughing and expectoration, the input of receptor impulses to the cough center and the output of cough center excitement are mainly through the vagus nerve. During the day, the excitability of the vagus nerve is relatively not very high, so we will feel that coughs during the day are often not very serious. However, after sleeping at night, the excitability of the vagus nerve will increase, causing the bronchial smooth muscles to contract, causing the bronchial tubes to swell. The cavity deforms and shrinks, the sensitivity of the respiratory tract increases, and coupled with the stimulation of respiratory secretions, coughing will become more severe and frequent. This is the reason for severe coughing at night. If you have a severe cough at night, you must first keep the air in the bedroom moist and not dry. When you have a severe cough at night, you can drink a large sip of cold boiled water to reduce the cough. The other thing is to find the cause of the cough and treat it symptomatically.