Very complete book in the way that it cover almost every aspect related to sleep, which is great, but the problem is that it never get really deep in any aspect, it always stay on the surface. If you just start to develop an interest in the subject I guess this could be a good introduction to it and then targeted a bit more where you want to go from there, but if you already read a lot about it, like I did, then you might think that this book just doesn’t bring nothing really new and the fact that it didn’t go deep enough anywhere probably will let you disappointed.