walk when sleep!

It really isn't a "special" problem as you put it. It's actually really common- almost all children sleepwalk at some point, and around half sleepwalk more often than once every three days. I don't know if your cousin is an adult or a child, but even so, it isn't too much of a problem, and you shouldn't be worried. The only thing you could do would be to make sure there wasn't anything harmful on his floor or anything that he might stand on and hurt himself whilst he's sleeping.

When I was younger I often woke up under the bed, under the table or in another bed. I was really surprised how I got there the next morning. Nowadays this is over, I don't do this things anymore. But when I am asleep and somebody wakes me up and I am awake only a short period of time, I usually won't remember the next day. When somebody tells me that I was up, I always think that he is kidding me. Maybe I act instinctively then, otherwise I cannot explain how this things happen. I also have a cousin who talks during his sleep and he is not aware at all. His father jokes around saying that he doesn't have to keep an eye on his son, because he tells him in his sleep what he has done. The case is not so serious, he only says a few sentences, usually exclamations, like go away, hurray, and things like this.

It's a sleeping disorder and psychological case. It is called as nightmare. it happens during REM sleeping stage . Please browse the link : http://www.lucidity.com/EWLD10.html