cmind is right, any type of thinking that demands your attention or some kind of focus is going to make it harder to fall asleep if not keep you up altogether. The key to getting back to sleep is to let your mind continue to talk or whatever it wants, but don't force the thinking... it will happen on its own. If you "listen" to the babbling it starts to get pretty random and nonsensical, it's neat to hear what comes up sometimes, but actively listening will probably keep you awake too.