Well maybe not everyone runs of caffeine and not every thought is inappropriate. But, do you notice how our mind never really shuts off? We are always thinking something. Much of what we this has to do with what is currently going on in our lives, or what happened, or what we think will happen. Notice how much emotion is experienced from these thoughts? Ever once ask your mind if what it thinks will happen, can it actually guarantee that it will happen? Ever ask yourself if you could have done anything differently than what you did at that time? Unless you have a way of knowing the future and fixing the past you will start to see these thoughts as cheap entertainment.