Those dark circles are essentially bruises,
This site does a pretty good job of explaining what causes them and there's a decent list of home remedies.
This page also has some interesting information.
I use a cream that I get from the health food store that contains
Arnica Montana and it works well for me... I apply it 2 or 3 times a week at bedtime.
If you decide to try that, do an allergy test first by rubbing some on your inner arm, near your elbow and wait 24 hours- if there is any reddness, swelling or other sign of irritation, do not use Arnica.
Actually, you should be that cautious about ANY preparation you're going to put on the delicate skin around your eyes, but most commercially available creams have a low incidence of allergic reaction.
Whatever cream or gel you choose, apply a little at a time and pat it gently into the skin, do not rub- rubbing is one of the causes of those circles in the first place.
