The skin of the lower eyelid is covered by so-called connective tissue. Beneath it is a layer of fat that supports it and keeps the skin distended. When this fatty layer decreases in size, the skin becomes slightly wrinkled, which can make it look darker. “To get an idea of how this happens, just look at the skin that covers the joint on the inside that joins the arm to the forearm. When they are stretched, and consequently the skin too, the color is lighter. As the arm is bent, the skin wrinkles and becomes darker”, explains dermatologist Luiz Carlos Cucê, from the Hospital das Clínicas in São Paulo. According to him, several biological factors can cause a decrease in the adipose layer, causing dark circles: heredity, few hours of sleep, physical constitution (thin people tend to have more dark circles), physical or mental fatigue and emotional tension, among others.
If the adipose tissue that supports the lower eyelid is reduced in size, the skin wrinkles and darkens, forming dark circles.