How do books have an effect on a person's emotional state?

I also asked fellow students on how do books change their emotional state, and I received some interesting feedback. Several student claimed that they didn't experience any change in their emotional state. Quite a significant amount of students (around 30%) claimed that 'When I read an interesting story, I feel as if I'm spectating the story', or, in other words, addiction to the story, as if they 'captured' that person's brain, and then their real life emotional state becomes captured and changes, according the the theme of the world. Also quite a significant portion of the fellow students I asked also commented on how reading a book has relaxing properties, helping a person to relax, and, as one student claims, 'like adults with alcohol'