In the first part of this series about the romantic novel, presenter Daisy Goodwin looks at the enormous industry romantic fiction has become today, and asks why this most derided of literary genres remains so enduringly popular. She performs a scientific experiment to prove that reading romantic novels can lower your stress levels and also finds that they can improve your sex life and make you sleep better. Contributors include Jilly Cooper, Joanna Trollope, Sophie Kinsella and Marian Keyes.