Toddler getting to sleep?

My daughter has always been really good at going to sleep, she made the transition from crib to toddler bed really well. But now I can't get her to sleep before 10 at night (she used to go to sleep at 8) and she'll wake up at 4:30 AM. When she used to wake up she would simply roll over and go back to sleep or cry a little and I would comfort then she'd go back to sleep. Lately, she gets up and tears down the baby gate and starts to wander around the house, cleverly avoiding mommy and daddy's room. I catch her after a few minutes and the only way I can get her to go back to sleep is to get into bed with him. What do I do? I have a suspicion that the new kittens I have are trying to play with her and tend to wake her up. What would you suggest? I'm about to lock the cats up in the bathroom with food, litter and water.