A three-month-old baby wakes up at four o’clock in the morning every day, which may be related to the environment, hunger, gastrointestinal discomfort and so on. 1. Environment: If the baby sleeps in a bad indoor environment, the temperature is too high or too low, the baby wears too many clothes, sleeps in a place where the light is too bright, the environment is noisy, etc., all may affect the baby’s sleep. 2. Hunger: the baby did not eat enough before going to bed, when hungry will also cause early waking up, may also be accompanied by symptoms of crying. 3. gastrointestinal discomfort: baby gastrointestinal dysfunction, such as drinking too much milk, can cause bloating, abdominal pain, indigestion and other discomfort symptoms, will also affect the baby sleep. Three months of the baby woke up at four o’clock in the morning every day, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.