Slaves of Sleep is a science fantasy novel by American writer L. Ron Hubbard. It was first published in book form in 1948 by Shasta Publishers; the novel originally appeared in a July 1939 issue of pulp fantasy fiction magazine Unknown. The novel presents a story in which a man travels to a parallel universe ruled by Ifrits. The protagonist takes on the identity of a human in this dimension, and becomes involved in the politics of Ifrits in this fictional "Arabian Nights" world. Source: Wikipedia (en)