Milk protein allergy can cause severe sleep disorders in infants and children. Milk allergy is often clinically difficult to distinguish from colic because it begins at the same age and is accompanied by less sleep, irritability, and intermittent nighttime crying. Typical manifestations are nighttime awakenings (5-6 per night) and a shortened total sleep time. Crying is also frequent during the day. Physical examination is unremarkable, and some babies may have anemia or blood in the stool. The diagnostic section is based on clinical signs and allergy tests. Allergy tests often show an increased level of immunoglobulin lgE and a positive milk protein radioallergic absorption test, or RAST. Babies with a history of milk allergy, once diagnosed, can be fed amino acid formula or deeply hydrolyzed protein formula for a few weeks to resolve sleep disturbances. Prevention of cow’s milk allergy in babies should start with the first milk after birth. If the first milk is formula it can easily lead to cow’s milk protein allergy, even if the baby is exclusively breastfed later, if the mother feeds cow’s milk or eats any food containing cow’s milk it can cause an allergic reaction in the baby. Reminder: A 3-month-old baby suddenly does not like to eat milk, but can drink some water, why? First, problems such as fever, diarrhea, vomiting or poor spirit should be ruled out. If the baby does not have these problems, the possible reason is too much milk. Babies less than 3 months old cannot fully absorb the protein in milk, even when they eat too much milk, it will not cause too much protein absorption and will not increase the burden on liver and kidneys. However, after 3 months of age, babies have an increased ability to absorb protein from milk, which increases the workload of the liver and kidneys, causing “fatigue” over time, which is reflected in a decreased appetite and a lack of interest in eating milk. For this kind of babies, you can dilute the milk or feed them when they seem to be sleeping. As long as the baby is drinking enough water, there will be no problem. After 10 days, when the liver and kidneys get enough rest and recover their functions, the baby will like to eat milk again.