Four-month-old babies are always rolling over in their sleep, which may be a normal phenomenon, or it may be caused by the lack of vitamin D and calcium, indigestion and other reasons. 1. Normal phenomenon: If the four-month-old baby is in a sleep environment with too much light, noisy environment, etc., it may cause the baby always roll over in sleep, which is a normal physiological phenomenon. If the baby has no other discomfort, parents can create a quiet sleep environment for the baby. 2. lack of vitamin D and calcium: four months baby sleep is always turning over, if also accompanied by sweating, pillow baldness, easy to startle, and even the phenomenon of night crying, may be the lack of vitamin D caused by poor absorption of calcium caused. 3. indigestion: four months the baby’s digestive system is relatively fragile, improper diet will lead to gastrointestinal flora imbalance, caused by indigestion, thus appearing to sleep all the time turn over, and even accompanied by vomiting, stomach pain and other symptoms. Four month old babies always turn over in their sleep, there may be other reasons, it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.