J.J.
I remember going through this not too long ago....My 2 1/2 year old daugter sleeps on the second level of our home and our bedroom is on the main floor. When we moved her to a toddler bed we were concerned about her safety (falling down the stairs), so we put a gate up each night in her doorway (and we still use the baby monitor, so we can hear her if she wakes up in the middle of the night). She did have a little light up aquarium thing that plays music on her crib and we moved it to her headboard--this has been so helpful! Most nights we hear her turn that music on in the middle of the night (self soothing behavior to get back to sleep). I've found that if we use something (like a blanket or the light-up aquarium--something that she has access to in the middle of the night when we're not there) to initially put her to bed at night then if she wakes up in the middle of the night she looks for that ojbect to self-soothe herself back to sleep. With our first child we rocked her to sleep each night, so guess what she expected when she woke up in the middle of the night....yep, mom or dad had to rock her back to sleep. We've wised up a little the second time around, but each kid is so different, aren't they?