running or dreaming?

Today, a friend of mine thoughtfully pointed out that the act of running produces much of the same effects as a nightmare... alone, in the dark, sweating, heart racing... I found this to be the funniest thing I have heard in a long time. It is true for many, my dream of running is a nightmare. He reminded me that, not long ago, all of those things would signal a "save your life, run away" reaction. So what is it exactly that I am fleeing from? My kids? sure. The monotony of life? Of course. So what brings me back, repeatedly? Most days, I choose to get up before the crack of dawn and drive my body into a sweaty, heart pumping, legs aching, exhausted state. When I return home my heart is still racing, i am dripping in sweat, and it is usually still dark. Maybe I should try and figure that out tomorrow morning... for now, when the kids wake up with a nightmare, I'll just tell them everything is okay... they were just going for a run.