When I went to bed last night I planned to read for a little while. I picked up a book of analytical philosophy I've been reading. I thought of the densely constructed arguments involving detailed analysis of individual sentence forms that awaited me inside. I dropped the book back onto my nightstand, shut off the light, and fell asleep a moment later.
So, I've been reading books so boring that it's not even necessary to get to the words inside to be put to sleep -- simply touching them is enough.