Such is the power of brain that it can create dopamine, i.e. the satisfaction of happiness giving hormone or it can go into a deep slumber of darkness where nothing feels right. In the Harry Potter series, the Author JK Rowling had specifically added the character of Dementor, a magical creature that would guard the Prison of Azkaban and their characteristic being their ability to feed on human emotion and memories of happiness, leaving their prey with nothing but all the worst experiences of his life.