If a newborn baby has very rapid breathing while sleeping, it is mainly considered to be caused by the following two reasons. The first is due to various fevers. If a newborn has an acute upper respiratory tract infection, acute gastroenteritis, or even an acute central nervous system infection, most of them will cause fever in newborns. After the fever, the newborn will often have shortness of breath, and often accompanied by an accelerated heart rate, which is caused by the increase in metabolism of the newborn caused by the fever, and after the fever subsides, the symptoms of shortness of breath will disappear. The second is caused by neonatal pneumonia, if the newborn suffers from pneumonia, it will cause alveolar lesions, and after the alveolar lesions, it will lead to the symptoms of hypoxia, and the newborn’s hypoxia will lead to a compensatory increase in breathing, and the newborn will also have the symptoms of shortness of breath when sleeping.