S.S.
We went through this with my 7 and 5 yr. old. It drove me crazy at night and they didn't seem to get enough sleep for months!! We couldn't split them back up to separate bedrooms so some nights I would lie in their doorway and read until they went to sleep and kept shushing them so they couldn't play. Mine would do little flips, giggle and then eventually fight and cry before falling asleep in tears. Anyway... TIME has been the fix. After 5 months of the newness wearing off, they have settled down and only have a bad night about once every 3 weeks or so. We just noticed this improvement and it has been pleasant. Good luck!