What is the theme in Blue Is for Nightmares by Laurie Faria Stolarz?

Sex plays an important role in this story. Even when Stacey has an important task she needs to accomplish, it constantly interferes with her thoughts and leads to her preoccupation about Chad. Her thoughts about Chad are quite intense. Sometimes her thoughts are only about love and sometimes they are quite sensual. Even when she doesn't think about Chad, she subconsciously thinks about love, just as it happens when she arranges her chips in the shape of heart in the cafeteria during her meal after her French class.