The ingenious neurobiology of mammalian sleep has been mathematically modeled to streamline A.I. memory and storage capacity — Dreams are, for the most part, delightful. As we sleep, visual and audio fragments combine into nonsensical snippets and epic narratives. Loosely recalled moments merge with vivid, imagined scenes; we interact with characters known and characters conjured up; we explore our fantasies and, sometimes, face our fears. …