According to WebMD: The medical term for sleep talking is somniloquy. Half of all kids between the ages of 3 and 10 years old carry on conversations while asleep, and a small number of adults — about 5% — keep chit-chatting after they go to bed. The utterances can take place occasionally or every night. A 2004 poll showed that more than 1 in 10 young children converse in their sleep more than a few nights a week. Overall, it’s says it’s a harmless sleep disorder. But it could be linked to nightmares or night terrors.
The kids have been talking in their sleep lately, not at the same time of course. When it happens, they both usually sound like they are remembering an earlier squabble. I thought maybe it’s stress from being in nursery school, or watching certain tv shows. They seem fine when they wake up but I wonder still if there is something to prevent it or if they will naturally stop as they get older.