@CH23: i'm with you. i only put the light on when it's needed (dark in other words) as far as i'm concerned i want the screen to look (resemble) as close as it possibly can to reading a physical book.
i believe that experience is best achieved by having any ereader light switched off. when the light is on it's more like a tablet albeit not as intensely bright.
of course the light does come in very useful occasionally for when it's pitch black
best wishes koboy