The following are some of the reasons why babies tend to cry at night: 1, the baby’s mother’s milk is not enough, the baby is not full, easily woken up at night by hunger, so there will be the phenomenon of crying in the middle of the night. 2, tummy discomfort, pent-up food, flatulence or intestinal cramps and other diseases, so the baby is not comfortable, so it will cry in the middle of the night. Parents should carefully observe other symptoms when the baby cries, so that they can seek medical attention in time. 3, lack of vitamin D and calcium, resulting in the baby sleep at night, easy to wake up, cry, along with occipital baldness and night sweats and other symptoms. 4, immature neurological development of the brain, in the baby 4-5 months, with the development of the nervous system and active cerebral cortex, there will be poor sleep and wake up more often than when they were children.