Baby Talking ALL Night

[XXLINZIXX]

One of my 7 month ols twins chats away to himself, most of the time inhis sleep, for most of the night. If I leave him, sometimes he quietens down by himself, but mosy of the time it eventually leads to crying. I can then usually settle him by popping his dummy back in, but this can take several attempts and then this goes on and on for hours. Maybe he is just a talker, but any ideas why this could be, is he not relaxing as he should??? It's pretty loudand keeping us all awake! Long shot I know x