Breasts are very soft a lie down flat is a normal phenomenon, breasts are mainly composed of about 70% breast tissue and 30% fat tissue, there is no muscle or bone to support the breast bulge, the breast touch soft, comfortable. In the standing breast projection is mainly local skin pulling force, once lying down the skin tissue on the breast and did not form a pull, the breast fat tissue due to the role of gravity will be scattered around, the chest a lie down on the phenomenon of flat. Chest is very soft a lie down on the flat is a normal physiological phenomenon, no need to overstress, in daily life can moderately do chest expansion exercise, enhance the elasticity of the pectoralis major muscle and skin, keep the breast upright state. Should wear loose, breathable, cotton underwear, to avoid excessive pressure on the breast.