Sleeping on the side does not usually lead to a large or small face.
In daily life, healthy adults sleeping on the side will generally not lead to large and small face, because normal people sleeping on the side, the body will be uncomfortable because of the same position for a long time, will often change the position, generally will not appear large and small face.
Most of the reasons for the emergence of large and small face is that one side of the teeth due to various reasons can not chew food, will be a long time with the same side of the chewing food, often chewing things on the side of the face will become larger. If one side of the face has nerve and muscle damage due to trauma or other reasons, it loses its normal function and the affected side of the face becomes smaller than the other side.
In order to avoid the appearance of large and small face, do not often use one side to chew food, if the teeth and face problems, timely to the regular hospital treatment.