If you're like most nine-to-five workers, you probably feel a bit slow sometime after lunch. Maybe you reach for another cup of coffee or tea. Maybe you grab some fresh air, a piece of fruit or something sweet and sugary to get you through. But in many cases what you really want is to place your head on your desk and close your eyes for a few minutes. Of course you can't though—what employer in its right mind would let you do that?