Your mind is never inactive.
Random thoughts flow even when you sleep. Your mind tries to make sense of thoughts.
If you were awake you have a choice not to pay attention to random thoughts. But, when you are asleep, you mind makes everything a story.
Find Peace and Calm: http://themeaningisyou.com/2011/07/08/fi…
Usually our brain.
Human brain is really complex, we know little about it
There is not scientifically confirmed reason
It is fascinating that we have no answer for 90% of things that happen around us.
Our every day life makes us dream. Our dreams combine verbal, visual and emotional stimuli into a sometimes broken, nonsensical but often entertaining story line.