Babies always cough when sleeping, often related to improper lying position, environmental factors, allergies, the presence of foreign bodies, respiratory infections and other reasons. Parents should carefully observe the baby and analyze the cause in the specific case.1. Inappropriate lying position: If the baby is lying down, the pillow is too low plus the cardia sphincter is not fully developed, which leads to gastroesophageal reflux and stimulates the pharyngeal mucosa causing a cough at night.2. Environmental factors: When the baby is sleeping, the air is dry and the amount of water is low, which may stimulate the pharynx, resulting in a cough reflex. Generally, if the temperature, humidity and cleanliness of the environment are properly improved, the baby’s coughing symptoms will improve; 3. Allergies: Especially babies with allergic cough or asthma, which are often relatively severe at night and may be less obvious during the day, must be given high priority. For chronic recurrent nocturnal cough, be sure to go to the hospital for allergy-related examinations, such as finding allergens and, if necessary, lung function tests to clarify the diagnosis; 4. Presence of foreign bodies: If foreign bodies are inhaled during the daytime, the cough will be more pronounced when lying down at night, and if necessary, go to the hospital for relevant examinations to remove the foreign bodies; 5. Respiratory tract infections: such as rhinitis, pharyngitis, laryngitis, etc., the upper respiratory tract stimulated by inflammation, nasal secretions reflux, etc. The cough may be relatively more symptomatic at night; 6. Other: if the baby has whooping cough, the cough will also be recurrent, with a predominantly nocturnal cough, accompanied by a special cockle-like high-pitched coughing sound, which needs to be clearly diagnosed and treated symptomatically. In addition, coughing symptoms can also occur if the baby has increased neural excitability or a weakened central inhibitory reflex during sleep.