I raised my girls so that if they came into our room to sleep
(normally during a thunderstorm) they would get
in bed, but then we would take them back to their own
bed once they were asleep, or we would go back to their room with them stay with them until they were asleep. This lasted until they were about 4 years old, then they stayed in their room.
This is an every night occurrance with her 6 year old. He doesn't sleep between us, but on her side of the bed.