Sunken eyes is usually due to hereditary but if you feel ,it is due to sudden weight loss
, you should take balanced diet
, lots of green vegetables & seasonal fruits. 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 light (Tyndall effect) or it is hereditary. Take plenty of fluids, sleep at night at right time. Apply cetaphil moisturing cream around eyes in day time & Fixderma under eye cream at night on dark circles for 3 months. 20 % to 80% improvement depending on the cause. If there is no improvement ,consult dermatologist
with MD or DNB Dermatogy qualification.