Thanks for asking the query. It is a myth that sunglasses cause dark circles or sunken ,their is no relevant facts which proves this. dark circle and sunken eyes can be due to other factors likes , deprived sleep,nutritional deficiency, stress, use of medications, pollution. so i would suggest you to have proper sleep each night, have healthy and balanced diet, exercise or do meditation if possible, avoid taking stress. drink plenty of water to keep your body and skin hydrated. also apply sun screen lotion before exposure to sun. regards. hope this helps .