Have you ever looked in the mirror at your eye when you turn the lights off? Well, if you haven't, then you're missing out on a really cool opportunity :). 

  When you first turn off the ligths before you go to bed, your pupil larges in size!! :O This happens because your eye needs to work harder to see in the dark. And your pupil shrinks very quickly when you turn the lights on in the morning, because your eyes havn't been used to the light. Very cool stuff, I know.