Different people have different sleep patterns. I knew a lady once who slept three hours a night and was fine. Yet others get 9 or 10 hours a night and seem always exhausted. If you are rested enough when you get up, then you are getting enough for you. If you're not, you need to adjust your schedule to match your needs.
Probably habit, sweetie. I'm afraid I got into that habit and then got narcolepsy, where I kept falling asleep randomly, even driving. What you need to do is just slowly start going to bed earlier (starting with maybe 20 minutes or so) and doing that for a few nights. I found the key for me was I was staying up late on the computer until I got sleepy. Well, the trick is starting to wind down about 45 min. to an hour before bedtime and stop doing anything that would be stimulating to the brain (i.e., video games, the computer. etc.). Try maybe just watching tv or something. Do this until you get down to a decent time. It's a scientific fact that the more sleep you get before midnight, the better rested you'll be. Good luck in your quest!!!!
Oh, dear! My life just flashed before me! My daddy used to search my room for flashlights before I went to bed because I'd cover my head with the covers and read in bed because I couldn't sleep, and then they couldn't wake me up in the am! I've been on a different time schedule all my life! It sure makes it hard for us "owls" to work and live with "larks"! Good luck!