I sleep for 12 hours and still wake up tired. Sleeping 8 hours doesn't help. What should I do?

See your doctor. Sounds like you're putting in the hours, but still feeling tired. This could mean the quality of sleep isn't good. I'd avoid alcohol before bed, as well as Benadryl (diphenhydramine) and those pm cold meds (they can put you to sleep, but it isn't great sleep). If you snore a lot, ask your doctor about sleep apnea. Your family doctor should feel comfortable evaluating you further. Good luck!
Sleep specialist. This could be from a number of things: 1) other medical conditions 2) primary sleep disorder 3) stress/depression. It is best to be evaluated by a sleep specialist who can fully evaluate all factors. You may need a sleep study.