Dark circles under eyes seem permanent?

i never use to have bags under my eyes before the age of 14. but after i started having really dark circles/bags under my eyes. i am now 18 and i still have bags under my eyes all the time. usually on days when i dont have much sleep, they get darker. but even on a full night of sleep, i still have them. im pretty sure its not hereditary, because if i didnt have it before why is it being permanent now? im starting to think its my diet, because i usually consume alot of caffeine and sugar from soft drinks, and hardly drink water. i guess u could say im addicted to them. its really driving me nuts because people always tell me to "wake up" and call me a zombie cuz i always look tired.