There seems to be this casual understanding that reading is an inherently relaxing activity, and that you can pull out a book before bed and wind down that way, regardless of what the book is about or what kind of day you've just had.
Of course, once you say it out loud, you can see at once that doesn't make any sense. So let's do a little bit of digging into what kind of reading is relaxing, and when reading might work to help you wind down (or if that's even a real option for you).
Let's get the really obvious thoughts out of the way first, shall we?
If the book is new, exciting, or very tense, it's unlikely that it will be conducive to relaxing, even if the act of reading can help unwind you from whatever real-life drama you've been dealing with. It's wonderful to escape into a different world with characters you love and interesting things happening. But the exciting things in the book that make it wonderful to escape into will stimulate your mind in ways that will keep you awake. If sleeping is the end goal, then you can see where that might be problematic.
If sleeping is not the end goal - if, for example, you're reading during your lunch break to get away from the unending office grind - then this obviously isn't a problem, though it might make it hard to concentrate on work if you don't have time to finish a dramatic or climactic scene.
I find that for the purposes of lulling myself to sleep, the best books are the ones that I've read many times before, so the story is familiar and I don't (generally) feel on tenterhooks waiting to see what will happen next.
I had a friend, however, who said that reading was simply uninteresting if she knew what was going to happen, so she would choose books that had short chapters to read before bed, so she could be sure to complete the scene before sleeping, but still be engaged enough to be interested.
So here's my question for you, Readers - what makes a good bedtime book for you?