Newborns sleep suddenly frightened trembling, may be the development of the nervous system is imperfect, sleep environmental factors, nutritional element deficiency, etc. caused by. 1. Imperfect development of the nervous system: newborns are still relatively small, the development of the nervous system is not yet perfect, easy to generalize the phenomenon, in the sleep will suddenly appear this phenomenon, with the gradual development of the nervous system, the symptoms will be relieved. 2. Sleep environment factors: may be the baby sleep, sleep environment is too noisy or indoor temperature is too high, the baby sleep is not stable, prone to sudden shock trembling phenomenon. 3. Nutritional element deficiency: most of them are caused by the serious lack of calcium in the mother’s body in the late stages of pregnancy, when the newborn baby calcium deficiency phenomenon, it is easy to lead to sleep fright and trembling. Newborns sleep suddenly frightened and trembling, 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.