actually i can easily see the appeal of that since i have faced exactly the same problem (me and xkcd man, reading paperbacks in bed in the same position !), and since i too have a deep appreciation for laziness.
however, i've got my own little system worked out involving a pillow. if i fall asleep, i still get woken up by the thing falling over, but i actually prefer that, as i'm a bit too paranoid to want to let it stay in the bed all night long. you just never know what could happen to it. i'll keep that system in mind though...