This article appeared in the January/February 2022 issue of Discover magazine as "Sleep Signals". Become a subscriber for unlimited access to our archive.
In a dream, fluorescent lights flicker over your head. Short, short, long … short, long. It’s Morse code, sent from a scientist in the waking world who’s watching you sleep under a light they’re controlling. After receiving the full message, you shift your closed eyes left then right, four times, to signal your reply.
During a lucid dream, people are aware they’re dreaming. Skilled lucid dreamers not only have these dreams often, but they can remember instructions given to them before falling asleep. This allows dreamers in a lab setting to respond — often with strategic eye movements — to onlooking researchers who send prompts to the sleeping subjects. In April, researchers reported that they talked to lucid dreamers, and the dreamers talked back.
“When I first ...
