I was given some advice on this once: Lie in bed at night (make sure it is dark so your eyes don't try to focus on anything). Do some eye exercises (up-down, l

I was given some advice on this once: Lie in bed at night (make sure it is dark so your eyes don't try to focus on anything). Do some eye exercises (up-down, left-right, generally just moving them around a bit) while your eyes are open. I think the rationale behind this is that when you stare at a screen not only are your eyes focusing at the same distance but they are not moving around as much as they should be. Don't know if this is scientific so caveat emptor etc.