Young babies usually have problems with crying at night. The reasons that cause babies to cry suddenly come from many sources, which may be caused by fresh weaning, unaccustomed diet, or frightened. It is generally related to discomfort caused by poor sleeping conditions, unsound brain and nerve development or physical illness. 1.Baby’s brain nerve development is not yet sound, and during the night sleep, due to the sudden excitement of nerve function, that can show sudden crying. 2.Sometimes infants over-eat or under-intake, infants will also express through crying. 3, poor sleep in young children can also be related to excessive excitement or tension before bedtime, or too much sleep during the day can also affect sleep at night. 4. Infants may also cry suddenly when they feel uncomfortable. If the diaper is not changed in time, or the clothes are too tight or the blanket is too thick, the baby will also tell the parents by crying. 5. Itchy skin caused by mosquito bites or eczema is also one of the reasons for babies to cry, especially at night when it is quiet. 6. Separation anxiety, babies do not want to be separated from their parents, are afraid of meeting new people, have a strong sense of self-protection in an unfamiliar environment, and are alert to the outside world (manifested in waking up more at night and sleeping lightly).