A.R.
We have that issue with my daughter, she gets up very early (5 am) and won't go back to bed. We got her a Wake Me Up Puppy alarm clock and told her she's not allowed out of bed till her puppy barks. She also earned tokens for staying in bed all night, then she can use the tokens to buy things (gum, tv show, 5 tokens to sleep with mom & dad, etc). It's worked pretty well.