The startle reaction occurs in infancy, often manifested as the baby can not sleep soundly, clenched fists twitching, accompanied by facial muscle twitching and so on. Infants sleep startle reaction, mainly because the baby’s young cerebral cortex is not fully developed, nerve excitability is not easy to be inhibited, so there will be the phenomenon of startle reaction, seizures usually clenched fists, mouth gently grunt, the whole body multiple muscle twitching, fall asleep after struggling and often wake up crying. Babies sleep jump reaction, should be appropriate to its soothing, try to keep the room quiet, and at the same time to observe the development of the baby, if necessary, early diagnosis and treatment, to avoid the emergence of serious diseases or sequelae.