Why Sleep? Why Dream?

Robert Lawrence Kuhn is the creator, writer and host of "Closer to Truth," a public television series and online resource that features the world's leading thinkers exploring humanity's deepest questions. Kuhn is co-editor, with John Leslie, of "The Mystery of Existence: Why Is There Anything at All?" (Wiley-Blackwell, 2013). Kuhn contributed this article to Live Science's Expert Voices: Op-Ed & Insights.