Common factors for frequent night waking of 4-month-old babies are vitamin D deficiency, gastrointestinal discomfort and insufficient food intake. Different reasons for different treatment methods, such as supplemental vitamin D, take probiotics or increase the amount of milk and so on. 1. Lack of vitamin D: If a four-month-old baby lacks vitamin D, it can lead to calcium and phosphorus metabolism disorders and increased nerve excitability, which may lead to frequent night waking. Vitamin D can be supplemented under the guidance of a physician, and if necessary, calcium supplementation therapy. 2. Gastrointestinal discomfort: gastrointestinal discomfort is mostly related to improper feeding, such as overfeeding. Children will have symptoms such as bloating, nausea and vomiting. Because of the stomach discomfort, which in turn will affect the sleep and frequent night waking. This condition can be treated with oral probiotics and compound pepsin granules under the guidance of a physician. 3. Insufficient food intake: If the baby’s breast milk intake is insufficient, the baby will wake up frequently because of hunger. In this case, the mother needs to pay attention to the baby’s breastfeeding amount, if the milk is not enough, you can also add some formula. The baby may also have other reasons for waking up frequently at night, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.