Lack of sleep.
Inherited condition having a family with the kind of skin that makes dark circles more likely.
Fluid retention which causes puffiness that may cast shadows.
Aging which thins and relaxes the skin around the eyes.
Food allergies or sensitivities can also contribute to dark circles.
An improper diet, an unbalanced diet or lack of a nutritious diet can cause dark circles under the eye.
Sometimes the dark circles are actually excess pigment in the skin of the lower eyelids, as if the skin had a huge freckle that covered much of the lower eyelid skin.
A lack of sleep or excessive tiredness can cause the skin under the eyes to become pale, thus, making the blood flowing under it visible.
Fluid Retention.

Treatment and Home Remedies for Darkcircles Under Eeyes

Dark Circles can be removed by applying peeled and grated potato overnight at least four times a week.
Massaging eyes with almond oil is of great help. Massage at bed time daily, and in two weeks you will see the difference.
Dark circles can be removed by doing pranayam daily for at least five minutes.
Make cotton pads and dip them in cucumber juice. Place on your eyes for 15 minutes. The effect is cooling and relaxes your eyes.
Pressing the mount below index fingerof the palm is good for eyesight and removing dark circles.
Dip cotton balls in rose water and keep for 10-15 minutes.
Take a diet rich in fruits and vegetables and avoid reading late at night, lying down.
Every morning, after washing your face, gently apply mixture of equal parts of tomato and lime juice.
Drink at least 10-12 glass of water each day to hydrate the skin.