Dream Catcher

I don't usually remember my sleeping dreams. I remembered it this time. It was a very common dream I have. I am taken back to the past, to an obstacle I found very difficult and my memory of the event finishing is removed so I have to go through it again. I was sitting an exam that I found difficult that I didn't finish on time and I am not sure I have written all the coursework so my head is racing away, then my memory is given back to me, I finished the exam years ago and handed in the coursework, the course I was doing was finished.

I don't know why my brain does that. Why does it take away my memory of a problem being solved so I have to try and solve it again. When my memory is given back to me, I feel a very strong feeling of peace or relief. I'm trying to solve a problem and the problem no longer exists. Instant tension them instant relief. What is going on in there?

My memory contains peace.  Thoughts that I have collected over the years that brings peace to me can be taken away in an instant when I am asleep and the peace they give me are no longer there. Tension then relief,  more tension then more relief. There is so much I don't understand in this world.