Under-eye bags are puffiness or bulging that occurs beneath the eyes, often caused by fat pads shifting forward as skin loses elasticity with age. The delicate under-eye area is prone to these changes because the skin there is thin and the supporting structures weaken over time. Bags can persist regardless of sleep quality and may be influenced by genetics, lifestyle factors, or fluid retention. They typically become more noticeable with age but can appear at various stages of life depending on individual anatomy and circumstances.