What causes newborns to be easily frightened?

Neonatal easily frightened common reasons are: a, neonatal nervous system development is not perfect, nerve cell system gradually increased, nerve myelination immature. Second, if the baby is too excited during the day, then a little stimulation at night will show more than scared. Third, if the baby has some special central nervous system diseases or gastrointestinal dysfunction, indigestion, etc., will show scared performance. Some babies due to calcium deficiency are also easily frightened.