There seems to be a pattern of specific nightmares which connect to certain times in your life or certain situations that you are facing. When you begin to have recurrent nightmares, you are definitely in a "transitional situation." For me, it was "the bridge."
I'd be driving along, minding my own business, and then there would be this bridge up ahead. At first, it was just a little bridge. But, as you got closer, it got higher and narrower and scarier . . . By the time you got near the top, the car was at an almost 90 degree angle to the ground, and you couldn't even see the top. You'd have to get out of the car and begin working your way along ropes and lattices to try and find the way back down.
At one point, it got to where I'd see the bridge up ahead and just go like Homer Simpson, "Dooh!"
Of course, there are the "good dreams" which can reoccur as well. So it's just like a little fairy land out there in sleep world, isn't it? Be careful in there.