is it healthy or unhealthy to sleep 12 hours a day, i am 19 by the way?!

Yes it is too long. You may want to keep steady hours, get your blood tested and catch a little vitamin D (sunlight). If you are drinking alcohol give it up for a little while.

You are still growing and you should listen to what your body is telling you. At the same time, if you are eating Cheetos, drinking pop, playing Call of Duty, having a couple joints and then falling asleep and just being a general lazy dumba**, then you should invest in some new friends because the ones you have now don't care a lick about you. If you are getting up and taking walks, enjoying the sun and living an active lifestyle, then you shouldn't worry about getting sleep and taking a nap now and again... But just remember, when you get a job, the boss usually doesn't like it when you take a nap for two hours and it can be a bear to break those habits...

It's healthy. Sleep as long as you want, you don't age when you're asleep. YOu'll only have more power and be more relaxed...even if at times you feel guilty or anxious...it's just social conditioning..

No the average time a person should sleep is atleast 10 hours a day, your fine

Votes for Jay's answer. He hit the nail right square on the head.