What a good nights sleep is to one person may not necessarily be the same amount for you. I know the rule of thumb is eight hours but you might need 9 or more. However, if you still have dark eye circles you can put cucumber slices on them for 15 minutes at a time. You could invest in some concealer as well if you're comfortable with the idea. Just make sure it matches your skin tone exactly.
it could be that you are deficient in a vitamin or mineral, like iron. I don't think anything can get rid of them except a healthy diet, if that doesn't work, I would suggest investing in a light- reflecting mineral concealer to apply lightly under your eyes before school/work/going out.