This statement might categorize almost every teen I have ever come into contact with. Most parent's have fond memories of cuddling in bed with their then 4 year old, making goo goo eyes at each other and whispering sweet "I Love Yous" in each other ears. Yes, the good old days. Now, "I love you," becomes, "I hate you, leave me alone!" as you cajole, then nudge, then outright scream for your teen to get out of their damn bed!
First a biology lesson. Of course you're teen can't get up at 6 AM if they don't go to bed till 11 or 12. Anyone can do the math. Unfortunately as your teen enters puberty their biological or circadian clock sets itself back a few hours, preparing itself for the longer days of adulthood, and need for less sleep. So their body/mind may actually not be ready for sleep until 11 PM. (Most adults I know barely can stay awake till 9:30, but you know grown-up hours!) Here is the kicker. Though their mind/body says stay awake, that one foot still in childhood is saying you need 9 hours of sleep a night for the brain to do all it's work. Therein lies the contradiction. You see how exhausted and out of sorts they are in the AM and know if they would just go to bed earlier, this whole problem would be solved. Ah if it were just that easy.
Being a person who suffers from some sleep issues, I know that if I get into bed too early, no matter how tired I am, I could be lying there for hours while sleep alludes me. 11:11 PM is my magic hour. I have tried, 10, 10:15, 10:45, as I fall asleep downstairs and then have to drag myself up to bed. But 11:11 it is, almost every night, and 15 minutes later I am asleep. Mission accomplished. I have worked with many parents on this issue, and many tell their young teens to be in bed by 9:30, knowing that will get them the required 9 hours. But what happens is these kids start to develop real sleep issues. Their brain is not ready to shut down yet, and sends them into pre-sleep anxiety about not being able to fall asleep. And because teens have so much on their minds, and are not used to quiet contemplation, (thank you cellphones, and computers) they kind of go out of their minds, and then start to dread bedtime. Then you have two struggles to deal with, going to bed and then getting up!
Your first job in diagnosing the "getting up" problem is to look at the going to sleep part of it. Your teen will either be a lark, an early morning person, or an owl, a late night person. Some of this is nature. You first have to accept who your teen is. Think about them from infancy to the present. Did they always fight you on bedtime, or were they that kid you could read one book and they were out like a light. This is an important step. Making your teen go to bed when you think they should go to bed will become a power struggle. Understanding that they might not be tired will make them feel less crazy, and open a discussion, as in "you know honey, you have always had a tough time getting to sleep, maybe you are more of a night owl than I am, we just have to figure out how to make your need to stay up later work with having to get up so early."
So for one week, just kind of observe the evening habits of your teen. Stay up as late as they do, so you can see what it is they do when you are not awake to see. It may be that they are staying up late texting, facebooking and video gaming which is highly stimulating, and can get in the way of the body/brain shutting down ,and readying itself for sleep. During this week long observation period refrain from commenting, just take notes. Tomorrow, what to do with this information, and the strategies for getting them up in the morning.