"Getting lost in a book" is not only a pleasurable feeling, but according to neuroscience, it is also a state where empathy networks become deeply engaged in the brain[1]. When readers connect emotionally with a character, brain activity is stimulated and strengthened.
The Heart-Mind Chapter Book list offers books that both "teach" social and emotional skills but also may provide a boost of feelings as young readers "get lost" in the story.
Researchers measured brain activity using Medical Resonance Imaging (MRI) in subjects reading passages from Harry Potter. Passages that were more emotional stimulated empathy networks in the brain. Fear, in particular, resulted in the strongest neural activity in the cingulate cortex (which is also associated with Executive Functions).