T.W.
I have an only child so I haven't experienced this from the mom point of view. However, my little sister and I shared a room until we were preteens. We are 3 years apart, and we both remember the days of playing together after lights out as some of the most fun we ever had. This was our plotting time, our decompressing time from the long day, and a bonding experience away from TV and our parents. Our parents just made our bedtime a little earlier b/c I really think we needed that time together to goof off and wind down. We are now insanely close sisters. For my own son, I know he needs to run around and play for awhile in his room before going to sleep, and once he finally gets tired enough to go to bed, he climbs in by himself and crashes for the whole night.