Hi hugs.
First a little background. My nightmares were all Claustrophobic "what ifs." All negative possibilities that had a 1% chance of ever having happened. But you know how association can take a disaster you see on TV. (an earthquake buries some people sort of thing) (a child falls down a well)
In many of my jobs I have had to squeeze into tight spaces and it never bothered me at the time. But just like negative thoughts in the triangle you can choose how you see past experiences. (my anxiety level is going up thinking about how bad my attacks were.)
I have never been stuck in a culvert but that was my worst trigger for panic attacks usually set off by being tangled in the sheets with a cat sitting on me.
Even though I woke up and got up for Ativan I could not stop the circle. Action-thought-reaction (panic) back to thought-reaction-thought-reaction building on the negative till the Ativan worked to break the thought.
I had been reading some fantasy one evening and in it these animals were crossing a road by using a culvert and hiding from the cars lights by waiting in it. They were fantasy animals like Frodo in lord of the rings.
Next nightmare when I woke up in a sweat I put the two together. I visualized the culvert bigger and me smaller and I was sitting in it with my back to the wall/side looking out of it. I felt safe rather than scared. In my mind I sat there safe looking at the world go by like a little mouse. In my mind I made the culvert as big as the one under the road by Baker creek down the road. It is about ten feet high.
Association allows a person to do this when you go from action to thought on the way to reaction.
I have had the nightmare often but now I go automatically to a bigger culvert and a safe place to be. BP drops back to normal, shakes stop and I go back to sleep.
I was always told I could find something positive in my memory to stop the negative thoughts but like I said thought moves at the speed of light and looks at things in your memory so fast and so many for it to stop and use something it has to be related or there more than once. It's importance level has to be high enough to grab on to and hold.
So if a person keeps filling their memory with negative things that is what you will get.
But see I built on those critters in their big culvert so I would have some association I could use.
I hope this made sense. It is amazing how well this works, so I hope it can work for you.
Davit.