Best-selling author Sylvia Day's first self-published title, "Bared to You," entered the New York Times best-seller list in April despite its cover, which featured a profile shot of a naked woman with her arms wrapped across her breasts and a man on his knees, his face pressed into the small of her back. When Berkley Books took over the title in May, the cover art changed to an image of a pair of cufflinks. The title is No. 4 on the New York Times best-seller list, right behind the three "Fifty Shades" books, and can be found on bookshelves in Target next to "Fifty Shades of Grey."

"Many new readers have discovered erotic romance and want to read more, but the more explicit covers don't appeal to them," said Cindy Hwang, executive editor of Berkley Books. "Publishers are smartly responding to the marketplace and adjusting the cover approach for some erotic romance titles. Cufflinks and keychains can be just as evocative as bare skin."

Day says she has received mixed reaction to the change from fans. Those who self-identify as avid readers and rely on cover art to identify the myriad subgenres within the romance category complained that the new cover obscured the novel's meaning. Others, however, welcomed the change and said it led them to finally purchase the book, where before, they didn't want to be seen carrying it around.

" 'Fifty Shades' readers and new readers of 'Bared to You' don't tend to self-identify as readers per se, and they want books they can take out in public, whereas romance readers don't care. They have adopted strategies over years, with e-books and book covers, and they'll go out with a book regardless of the cover," she said. "For those who are getting back into reading with 'Fifty Shades' and 'Bared to You,' it's a very new thing they're stepping into, and they want it to be an easy transition."

E-books have also helped to ease the transition by offering newcomers to the genre a way to read in virtual anonymity, said Twanna A. Hines, a New York-based writer, sex educator and reproductive rights advocate. Its second wave of popularity came through word of mouth once it started receiving widespread coverage in mainstream news outlets and popular culture.

"It's been parodied on 'SNL' and on the cover of Newsweek. Who wants to be left out of the conversation?" she said. "Plus, BDSM is appealing because while many Americans have heard of 'Fifty Shades of Grey' and can tell you it's an erotic book, not as many can tell you what the letters BDSM stand for, so there's this allure, the siren call to find out more."

For the next few months, expect publishers to bet on that desire and reissue more BDSM titles from the past dressed up in scarves, leather belts and feathers until the next trend rolls around.

"You can't create a moment like this, because if you could, we'd do it all the time," said Patterson, of St. Martin's Press. "It just ends up that the stars align and something breaks in a major way at the right time that ends up hitting readers and grows like wildfire. You can't really explain it all the way. It's just one of those moments."