Why do you get chilled when you're getting sick? What causes brain freeze? Why does your skin prune when wet? Why does your stomach growl and what is that sensation you get when your foot falls asleep? This video answers all that and more... Including explaining why your jerk awake when you're dozing in class or a boring meeting! Personally, I think it's your bodies way of busting you in such a way that your teacher or boss catches you every time!