Any sentiments, including your emotions, haunting thoughts and absorbing feelings from love to hate and fear (especially fear!) at once reveal themselves in astral and mental planes. Consequently, we see all these peaks and changes in our dreams. The most important that we see not only those we know about but also those which happened with other people or will happen in the future!
The stronger are feelings and the more haunting are thoughts, the brighter are images in our dreams. What, putting it plainly, are the major contents of our inner world? Our own thoughts, ideas and feelings. That is why our consciousness is most active on planes where they are free to act on their own, restoring worlds and universes.
Yet, in the same way as our inner world is filled with information from nerve terminals, organs of sight, hearing and touch making direct connection between outer signals and inner perception, everyone has a feedback from inner world to the outer one. However, such data transmission has one unique trait.