^ This works wonders for me. A nice paperback will help calm me down (you typically are only thinking about the book itself, and not any of your petty everyday issues that might keep you up at night), but just make sure that the book isn't too
good. I have had nights where I start reading at 10pm, and finally set the book down at 12pm, simply because it was too good of a book to stop reading.
As a side note, I think I benefit from positive thinking before I go to bed. My wandering mind never settles on negative aspects of my day, but I'm usually imagining some odd scenario where I'm giving a speech, or writing a paper on who knows what (I usually forget shortly after), or am simply having a conversation with a nameless persona.
One particularly memorable instance of monomania was when I was thinking about conducting an interview as the President of the United States of America, and was answering random questions about our country, or my views on any given subject.
Boy, was I crafty