Coughing when the baby falls asleep may be caused by environmental factors, respiratory diseases, allergies and other factors. 1. Environmental factors: such as low indoor temperature, dry air, etc., at night when sleeping stimulates the respiratory tract, resulting in symptoms of coughing while sleeping. 2. Respiratory diseases: caused by upper respiratory tract infections, inflammatory secretions stimulate the airways during sleep, leading to coughing. 3. Allergy: if you are allergic to bedding, air or dust, you will cough at night after being stimulated by allergens. It is recommended to give the child appropriate warm water to ease the symptoms of coughing, timely consultation to find the cause of the disease, timely improvement and treatment. If your baby is allergic, avoid contact with allergens in your daily life.