I feel that fiction novels (as others have said) present a wonderful way to temporarily escape the stresses of the day. The same can also be said, however, for non-fiction novels depending on the person reading. More importantly, I think that a good fictional story helps further develop the creativity of an individual. Facts that have been written down, I feel, do not challenge the reader's creative mind as much. Non-fiction is usually more easily related to life experiences and things that one has personally seen, heard, etc. A fiction, on the other hand, is generally more capable of presenting an image of something to your mind that is not so easily related to anything you've ever seen before. It challenges your mind to broaden your perceptions of the world around you to create an image that corresponds to a text description.

I could be wrong. Just my opinion, though.