The reasons why babies sleep and cough wake up without coughing include environmental factors, allergic cough, bronchitis and so on. 1. Environmental factors: after sleeping at night with doors and windows closed, the air does not circulate or the indoor air is not fresh, the baby will use his mouth to breathe, which for a long time will cause the mucous membranes of the mouth and throat to dry out, resulting in the baby sleeping and coughing awake without sleeping. 2. Allergic cough: when the baby is allergic to certain substances, such as dust mites, animal fur, etc., stimulate increased respiratory secretions, manifested as paroxysmal irritating dry cough, usually in the early morning and at night when the coughing symptoms are the most intense, and seldom cough during the day. 3. bronchitis: baby respiratory system is not yet well developed, when infected by external germs, can be manifested as cough and phlegm symptoms, sleep at night after lying down respiratory secretions flow to the direction of the trachea, during the day when the baby is in a standing position, secretions will not flow into the oral cavity or the pharynx, so lead to the baby sleep cough woke up without coughing. Cause the baby sleep cough woke up without coughing there are other reasons, such as rhinitis, pneumonia, etc., it is recommended to the hospital in a timely manner to carry out relevant examinations, clear cause of the disease after active symptomatic treatment.