The causes of newborn crying at night may be physiologic, such as hunger, environmental discomfort, etc., or disease state, such as abdominal discomfort, vitamin D deficiency, fever, etc. 1. Physiological causes: (1) Hunger: lack of proper feeding at night will cause the newborn to be underfed and cry, while overfeeding will also lead to abdominal distension and nighttime crying. (2) Environmental discomfort: room temperature is too low or too high, or too much clothing, too bright, uncomfortable bed, too much noise, etc., will cause the child to sleep uneasily and cry at night. 2. Disease state: (1) Abdominal discomfort: when the child’s abdomen is cold, when he or she eats milk powder that is too cold, or when he or she is allergic to milk proteins, it may lead to colic, diarrhea, and crying at night. (2) Vitamin D deficiency: Vitamin D deficiency can lead to increased neural excitability in babies, resulting in nighttime crying, excessive sweating, and easy to startle. (3) Fever: when the baby is in the state of fever and other diseases, there will also be night crying. Newborns crying at night may also have 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.