What causes a newborns respiratory rate drop to 16 breaths per minute while sleeping?

It is normal for a newborn's respiratory rate to drop to 16 breaths per minute while sleeping. This is because their bodies are still developing and their breathing is regulated by the brainstem. The brainstem controls the basic functions of the body, such as breathing, heart rate, and blood pressure. As a newborn's body matures, their respiratory rate will increase and become more regular.