I can hardly sleep, and I have to fight for my night sleep because my brain wants to think, and analyze everything even when there's nothing to worry about. I get those "brain chatter" as you describe thinking nasty horrific thoughts as though you have a demon in your mind. I usually turn my brain channel to something else to keep me occupied and away from the brain chatter. The racing thoughts I haven't quite figured that one out yet, but I hate it; just a little less than I hate brain chatter, and both of them are high up on the list.

Remember: "That which is repressed will be expressed innappropriately."