You are in bed, sleeping and dreaming of your next adventure in the Swiss Alps. Your alarm has not gone off yet, but for some reason you are suddenly awake and feel incapable of moving…enough to get your heart racing and for your forehead to be a little moist.
What has happened? Why can’t you move? Did you break your spine in the night?
After about a minute, it’s over, and your body returns to normal…but the question remains, what happened?