I sometimes leave my laptop on with soft music playing but after
sometime it is rigged to turn off and its far enough away from me where they glow from the screen is not on me.
But yeah, I have wondered about the effects on us from staring at these screens as much as some of us do. Its really not a natural thing to be staring at a glowing thing for many hours a day but often I do. I also have an e-reader that I read from often But I think that is better on the eyes.. because it has a different type of screen.
Black and white and its mostly just text and the screen is realy nice too > like a matter surface with no glare or anything.
I like my Kindle touch e-reader > its small and very portable too.