Why do we dream?
Amanda Gefter writes: In the late nineteen-nineties, a neuroscientist named Mark Blumberg stood in a lab at the University of Iowa watching a litter of sleeping rats. Blumberg was then on the cusp of forty; the rats were newborns, and jerked and spasmed as they slept. Blumberg knew that the animals were fine. He had often seen his dogs twitch their paws while asleep. People, he knew, also twitch during sleep: our muscles contract to make small, sharp movements, and…