Sudden awakening and crying may be caused by physiological factors such as environmental overheating and hunger, as well as vitamin D deficiency rickets, nocturnal terrors, and other causes such as indigestion. 1. Physiological factors: If the baby sleeps in a high temperature environment, the baby may be woken up by heat while sleeping, and then the baby will suddenly wake up crying. In addition, if the infant has eaten too little before going to bed, the infant will feel hungry while sleeping, and then the infant will also show sudden awakening and crying. These are normal physiological phenomena and can be left untreated. 2. Vitamin D deficiency rickets: Vitamin D deficiency rickets is considered to be caused by insufficient supplementation of vitamin D in food, rapid growth of infants, chronic diarrhea and other reasons. Patients will have night terrors, excessive sweating, night crying, irritability and other manifestations. If the infant has vitamin D deficiency rickets, there will be sudden awakening and crying. 3. Night terrors: Night terrors may be caused by heredity, poor sleep environment, bad mood and other reasons. The patient will have waking up in sleep, anxiety, fear, shortness of breath, sweating and other manifestations. Therefore, infants with night terrors will show sudden awakening and crying. 4. Other: Infants with sudden awakening crying are also considered to be caused by indigestion, intussusception, intestinal obstruction, upper respiratory tract infection and so on. Suddenly waking up crying, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.