Find the cause whether it is due to night time awakening or some cosmetic you are applying under eyes or it is just effect of lights (Tyndall effect) or it is hereditary
Next Steps
Apply Fixderma under eye cream at night on dark circles for 3 months, 20 to80%improvement depends on the cause, take plenty of fluids, sleep at night at right time,apply cetaphil moisturing cream around your eyes along with Fixderma under eye cream,if no improvement consult dermatologist.