My six year old son is a sleep talker. He will carry out some very interesting conversations while he is asleep. Most of the times I have no idea what he is talking about but there have been a few times that he gets my husband and I practically rolling on the floor laughing. My husband is a sleep talker also so I am assuming Alex got it from his dad. They both are very heavy sleepers and once they are asleep they could probably sleep through a hurricane.
The funny thing is he has been talking in his sleep since he learned to talk. He coslept until he was two I swear to you that boy would keep me awake at night talking. He would chatter about nothing at all and he would be completely asleep.
Alex will usually wake up shortly before Chris and I go to bed and come down stairs and use the bathroom. He is usually half asleep when he does this and then he tries to carry on a conversation. Most of the time this is when he says some really funny things. He will sit down on the stairs, obviously half asleep and mumble that he needs to tell us something. It is usually something about this sister doing something crazy, even though she has been asleep for hours, another time he was trying to convince us that there was a purple bunny rabbit in his room and it would not let him go to sleep.
About once a month we let the kids camp out in their sleeping bags on the living room floor. Our bedroom is right off the living room and I can hear him in the middle of the night talking, you can always tell if he is having a good dream or a bad dream because his tone of voice changes and sometimes you can actually understand the conversations he is having. It can make sleeping in the same room or the next room interesting but it also makes us laugh.