The reason why children spit out white bubbles in their sleep may be physiological factors, oral diseases, pediatric pneumonia and so on. 1. Physiological reasons: some children’s oral secretion of saliva is more, but its swallowing ability is not perfect, which will lead to the emergence of the situation of spitting white bubbles while sleeping, which is normal. 2. Oral disease: If there are herpes, ulcers, gums red and swollen, etc., it will also lead to more saliva secretion in the mouth, which will lead to the child spitting white bubbles while sleeping. 3. Pediatric Pneumonia: If a child suffers from pneumonia, then there may be phlegm in the respiratory tract, which can lead to spitting white bubbles while sleeping. It mostly occurs in small babies. Children sleep spitting white bubbles, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.