Nipple pain should be caused by incorrect feeding posture. The baby should hold most of the areola. Some babies will suck a little nipple and it will break. Don't let your baby get into the habit of sleeping with his nipples. You are not allowed to eat milk when you sleep. If the baby has just given birth and there is no nipple pain, it is because there is too little milk and the breast hurts. The baby won't hurt after eating for a while. This is temporary, and so on.