Excess fat can also cause puffiness that casts shadows, making the area look dark.

Usually though, “dark circles are caused by the unique optical properties of the very thin eyelid skin,” Zeiva. “Just under the skin is a thin red muscle called the orbicularis oculi muscle. The light that penetrates the skin is absorbed by this muscle and makes the area look darker.”

At only half a millimeter thick, eyelid skin can also reveal the underlying blood vessels.

There’s often a combination of reasons for dark under-eye circles. Because of this, Zeiva may recommend more than one treatment.

“No one answer will improve the condition completely,” says Zeiva. “A combination of a quality skin regimen and addressing the underlying anatomic factors with laser tightening treatment or fillers will give you an optimal result.”

What are the most effective treatments for dark under-eye circles?

There are a number of nonsurgical ways to diminish under-eye circles that always make you look tired. From fillers, lasers and microneedling. Keep in mind, however, that “even with multiple treatment methods, dark circles can only be reduced, not completely eliminated.”