Although lack of sleep is the most common cause of dark circles under your eyes, there are other reasons that you may be getting them.
Staring at a screen for too long can enlarge the blood vessels around your eyes making the surrounding skin look darker.
Not drinking enough water can make the skin beneath your eyes look dull and darker, and your eyes look sunken.
Allergies can cause your blood vessels to dilate, making them look more visible beneath the delicate under eye skin.
Not enough iron in your diet can make your skin look paler than normal, so the blood vessels under your eyes start to show as dark circles.
Too much sun exposure on the delicate skin around your eyes can cause an excess of pigmentation making the surrounding skin look darker.
It could also be…
Genetics. If you’ve had dark circles since you were a teenager then they’re probably hereditary.