We had a similar hard time with our daughter's bedtime not long after she went into a 'big girl's bed', and also not long after her little brother had arrived! She must have been around 3, and started to get up when she'd never done it before, or shout out and wake the baby constantly. In the end, something really simple worked, we told her if she stayed in bed quietly we would go back and check on her after 2 minutes. If she kept calling out/ coming down there would be no tv (or now, chocolate milk)the next day. We would go in, give her a kiss, or just say, "Good girl,night night." After a couple of nights of this working we went in after 3 minutes, then 4. She is 5 now and she still says "Come and check on me in 4 minutes!" as we put her to bed, but in reality it's usually 15 minutes, or we forget until we go to bed. She's usually asleep after 1 check. I think she just felt insecure and if she knows we're around and will check on her she's not worried. Hope this helps, it's so hard to work out what they need, and they're all so different, but it might be worth a try? Good luck, Natalie