If your child is sweating a lot, shaking his head a lot when he first falls asleep, and sleeping for a short time during the day is also unreal, consider the lack of vitamin D as a cause of poor calcium absorption. Generally, a full-term child should start taking at least 400 units of vitamin D per day 14 days after birth. By this time, 400 units is not enough for him, so he needs to take more vitamin D. It is usually recommended to take up to 800 units per day and give him some additional calcium supplements. Calcium supplements are generally recommended for half a month for observation, and if the symptoms are relieved, just stop taking them for another week. If the child is still in this situation after calcium supplementation with vitamin D, it is recommended to go to the hospital for an interview to determine the vitamin D level.