If you ask a question of someone who is sleeping and they respond in a way that makes sense, you likely would think you had momentarily woken them. In reality, the person may still be in the middle of a dream at the same time they're interacting with you. Research from Northwestern University cognitive scientists showed that it's possible to have real-time dialogue between dreamers in the midst of REM sleep and those in the awake world. Much of their study focused on individuals in the midst of lucid dreams, when you're aware of the fact that you're dreaming and can often control what happens.
"We also showed that dreamers are capable of comprehending questions, engaging in working-memory operations, and producing answers," said psychologist Ken Paller.
From Northwestern Now:
"Our experimental goal is akin to finding a way to talk with an astronaut who is on another world, but in this case, the world is entirely fabricated on the basis of memories stored in the brain," the researchers write. They realized finding a means to communicate could open the door in future investigations to learn more about dreams, memory, and how memory storage depends on sleep, the researchers say[…]
One of the individuals who readily succeeded with two-way communication had narcolepsy and frequent lucid dreams. Among the others, some had lots of experience in lucid dreaming and others did not. Overall, the researchers found that it was possible for people, while dreaming, to follow instructions, do simple math, answer yes-or-no questions, or tell the difference between different sensory stimuli. They could respond using eye movements or by contracting facial muscles. The researchers refer to these successful conversations as "interactive dreaming." They chose questions with known answers so that they could assess whether participants' answers were correct.
(Psychology PhD student and lead author Karen] Konkoly says that future studies of dreaming could use these same methods to assess cognitive abilities during dreams versus wake. They also could help verify the accuracy of post-awakening dream reports. Outside of the laboratory, the methods could be used to help people in various ways, such as solving problems during sleep or offering nightmare sufferers novel ways to cope.
"Real-time dialogue between experimenters and dreamers during REM sleep" (Current Biology)
(via Daily Grail)