Another problem with juice and full-sugar soda is the calories. American children eat a diet that contains way too much sugar. Everything has sugar in it--fast food chains put sugar/ corn syrup in nearly everything. I'll spare you the "when-I-was-a-kid" stories, but when was the last time you served cabbage or turnips at a meal? (My mother's pet peeve was making us eat liver. I have not tasted liver in over fifty years---God, what a disgusting meat! Can't imagine why she liked it.)
The posters above are right on the money when it comes to nap time and bedtime. Sending a kid to his room as punishment is a spectacularly bad idea. First of all, it makes his bedroom a place of punishment. Second of all, most kids' rooms are all full of interesting things to do--games, toys, some kids have computer gmes and a TV in their room (bad idea.)
Restricting egress is another bad idea. I think it's kind of dangerous , but worse than that, it relieves the child of any need to learn to do what you tell him just because you said so. What's next if the string thing doesn't work? Handcuffs?
Best solution, wear 'em out in the afternoon running around at the park or whatever. Don't let them sleep very long in the late afternoon, just a short nap. Dinner, then put them in a nice, warm bathtub, brush teeth, jammies, say prayers, then into bed for a couple of interactive kids' books (What does the cow say? Moooo) and then, yeah, maybe Moby Dick or maybe Rise and Fall of the Third Reich. (If the kid doesn't go to sleep, at least you will!)
Children need a lot of reassurance at bedtime. You could lay down with them, or sit in a chair next to the bed and rub his back or sing a lullaby. My wife used to sing a song for our daughter at bedtime called "All the Pretty Horses." There was another one she would sing with her when she had to go to day care, etc., called "The Mommy-Comes-Back Song."
A special blanket or a favorite stuffed animal is good too. I'm not much of a fan of dogs sleeping in people beds, but hey, whatever works.
I believe in kids getting up early, too. Sleeping in 'til nine while Mom gets a little peace and quiet is just asking for trouble at bedtime.
Oh, and if you think they are a handfull now, wait until they hit thirteen or fourteen, you'll be ready to choke them!