The reasons for coughing at night when you have a cold are as follows: 1, when you sleep at night, your body is in a lying position, and your abdominal organs will cause your diaphragm to move upward, which will result in limited diastolic function of the lungs, and your cough at night will be more serious than during the day. 2, when you have a cold, your lungs need to detoxify more, and coughing is a way to effectively clean up your head, trachea, and bronchi from foreign substances, and around 3:00 am is the best time to detoxify your lungs. 3, when you sleep at night, the environment is drier. The best time for the lungs to detoxify is around 3:00 a.m., when coughing from 1:00 a.m. to 3:00 a.m. can cause severe coughing.3. The environment is drier at night when you sleep, such as the environment is too dry and the air is too turbid, the oxygen content is less will stimulate the lungs to produce a coughing reflex, so the patients with colds need to circulate the air before going to bed and humidify the environment.