Babies always wake up frequently in the second half of the night, first of all, we should clarify whether there is gastrointestinal discomfort, cold and other conditions, if these conditions are ruled out, frequent night waking in the second half of the night, sleeping with excessive sweating, night terrors and easy pillow baldness may be caused by vitamin D deficiency. Babies grow fast and have a high demand for vitamin D. Since the amount of their own synthesis is not enough, they need additional supplementation. Full-term newborns start daily physiological vitamin D supplementation two weeks after birth, and premature babies, low birth weight and twins should start supplementation one week after birth. All of the above should be supplemented until the child is about two weeks old, and attention should also be paid to giving the child more sun exposure to facilitate calcium absorption.