DD will fall asleep with a book, but we have also then caught her reading later (wakes up and starts reading again). This was particularly dangerous when she did this the week of MAP winter testing. Of course, by then, the PS had already done so much testing for the year, that I almost wanted to just let her read. wink

Good quality sleep is very important to learning and mood, though. So we tend to enforce "lights out" at a certain time.