There are many reasons why newborns are easily startled in their sleep, as follows: 1, newborns sleep with a sleep cycle, the sleep cycle is shorter than adults, the adult sleep cycle is an hour and a half, the newborn is an hour. May be affected by the external environment during light sleep to react; 2, a few children may have stomach discomfort, intestinal cramps, colic during sleep, the child may be in the process of colic or intestinal cramps, suddenly awakened and then startled; 3, children and adults the same, the sleep process may also be in the dreaming time can also have body movements, belongs to normal; 4, a few children sleep process has muscle tone change and have consciousness change, which may be caused by neurological diseases. The child may have convulsions during the waking process, and some children may also show convulsions during sleep. If there are frequent symptoms, it is still recommended to go to the hospital.