Probably the most noticeable effect of dark circles under the eyes, or eye hollows, is that people believe you are not getting enough sleep, depressed, stressed out, or showing your age.
And they’ll guess that you are 6 or 8 years older than you are. None of the above are actually causes of dark circles under the eyes. But they are probably the reason that dark circles under the eyes is the second most common dermatological complaint after acne.
The cause of dark circles under the eyes is the bursting of tiny blood vessels. These capillaries are so small that blood cells can only pass through in single file. Just as in normal bruising, when the capillaries burst, the blood cells break down and turn dark blue or black. And, just as in normal bruising, there is usually no serious medical concern.
So, what causes the capillaries to burst? Weaker capillaries, a genetic problem, have a greater tendency to burst. Rubbing the eyes will also cause them to break. And exposure to the sun, which activates melanin production, can also cause damage.
Allergies can bring on the dark circle effect because allergies often affect the eyes making them itchy. The allergy sufferer then rubs his/her eyes causing hundreds of capillaries to burst. Smoking, fumes, air pollution, bright lights—anything that irritates the eyes and compels rubbing could lead to dark circles.
Aging makes dark circles under the eyes more noticeable because our skin becomes thinner with age and therefore the blood vessels underneath become more visible. The layer of fatty tissue under the eye becomes thinner creating a hollow that emphasizes the dark-circle effect.