Many babies have a cough after they fall asleep. There are many reasons for this phenomenon, such as upper respiratory tract infection, influenza, whooping cough, throat spasms, rhinitis, sleep environment and sleep posture. Babies who sleep flat at night without a pillow are more likely to have nasopharyngeal secretions that irritate their throats while they are asleep, which in turn causes them to cough continuously while they sleep. So a small pillow can be appropriate when the baby is sleeping to help relieve the cough. If your baby has a cough and catches cold again at this time, it will cause the cough to become more serious. Therefore, it is also very important for your baby to sleep in an environment where the air in the room is not dry and odor-free, and to pay attention to keeping your baby properly warm and avoiding cold stimulation, which can also relieve the cough to some extent. If your baby has a serious cough after falling asleep, it is best to take him to the hospital for examination and treatment of the diseases that commonly cause nighttime coughs, such as allergic cough, cough variant asthma and upper airway syndrome. Your baby should drink more plain water and avoid spicy and stimulating foods.