Willa,
Maybe your sons need more intellectual stimulation. That was the recommendation from our pediatrician when our son was 5. We put him in an all-day self study academy. He was falling asleep early within a week.

Also, I have read several places that gifted kids often need less sleep than others. I really amazed by a 15 yo boy that doesn�t love to sleep. My now 10yo would sleep all day on Saturdays if we let him.