L.M.
I have to second Shellie's suggestion. My daughters, who are currently 7 and 5, have always shared a room, and for the last few months share a double bed. Because they can often get a little silly and loud instead of quieting down (even when one or both is exhausted), I often have to separate them. One goes to sleep in her bed, and the other in mine. I move the one to her own bed when I go to bed, and she sleeps through it every time. It works well for us, but the big one is getting to be quite heavy and long-legged when she's the one I have to relocate! :-)
Good luck with your wonderful little bundles of energy!