Dark circle may be due to... Frequent rubbing under eye Waking late night / Inadequate sleep Lack of nutrition in diet / Anaemia Dehydration Watching Mobile, Laptop / TV of long times Or Hereditary. Treatment would be accordingly. Change your lifestyle Drink plenty of water Add more of fresh fruits and veggies in your diet. Sleep adequately 6-8 hrs Apply sunscreen around eyes Put moisturiser daily at night before sleep. To lighten your skin you can use depigmenting (Advan) cream at bed time and sunscreen (Photostable) in morning(8 AM) and afternoon(12 noon). You can also take oral vitamin C tab daily. Take Care