Question:
Today I remembered how several books I've read talk about how your body can't tell the difference between what is really happening in the world versus what you mind makes up about the world.

For example, if the world around you is calm, cool and serene, but you mind is imagining or generating imagery of danger, death and destruction, your body will respond to a certain degree as if it is facing danger, death and destruction.

One popular form of using your mind to directly influence and improve your physical body is the visualization that athletes do. I've read (don't remember the name of the book, but I'm sure about what I read) that when scientists tested athletes during the time they were visualizing competing in their event, they found that the athlete's body was responding as if the event was actually occuring.

Long story short - just another reason not to let your brain freak out. If you do, you're body will react as if it's more than just a dream. Of course we all know that already, just thought I would raise it again in context of the mental "the world is ending" fantasy we put our bodies through after being diagnosed.

Answer:
What an interesting insight, that would make a lot of sense.

I run round 100 miles per hour in my mind,always thinking of the next hour/day/week/event.

Yet i am always in a state of exhaustion,i wake up so tired and have had so many dreams,my mind i know has still been very active.
Everyone else around me seems so chilled and refreshed,if only i had an on and off switch!