Babies do not sleep soundly at night, you can hang up the pediatrician. The cause of baby’s sleeplessness is generally considered to be related to gastrointestinal function or lack of vitamin D. Most babies who have normal stools, normal feeding and no bloating can be ruled out. Most of the babies, if the stool is normal, eat milk normally, the stomach is not bloated, consider can rule out the digestive system disease, consider the lack of vitamin D, caused by the greater possibility. Full-term babies, generally 2 weeks after birth, should start supplementing vitamin D. Premature babies supplementation is even earlier, to be 1 week after birth to start supplementation, until the baby is about 2 years old. If the lack of vitamin D, the child will not sleep soundly, easy to startle, resulting in poor sleep quality, affecting growth and development.