when to read

I'm reading Hot, Flat and Crowded by Thomas Friedman and it is good so far. A book with lots of facts connected into trends and theories. But my biggest problem is that I keep picking it up to read an hour bfore bedtime, and its not long before the words start to blur together.
Yesterday I spent 20 minutes trying to get off of one particular page without skipping over sentences, and had to keep rereading to be sure I actually understood his points. I even read out loud to myself (am i the only one who does this?) to be sure I was following before I moved on. Then I realized... I had dropped my bookmark earlier, and was actually almost a dozen pages further into the book. That is to say, I had read these particular pages a few days ago. Not saying much for my understanding.
For now I am chalking it up to the fact that the beginning of the book is setting the stage- explaining why the earth is in an environmental crisis. This part is depressing. The author does promise he will discuss possible solutions in later sections, and this is the part I am eager for. I won't skip the groundwork, because likely he will refer to it. Indeed it should shape the arguments for why some courses of action are more favorable or more likey to work.
If only I can stay awake to get there.