25 February 2021

Dreams take us to what feels like a different reality. They also happen while we're fast asleep. So, you might not expect that a person in the midst of a vivid dream would be able to perceive questions and provide answers to them. But research shows that, in fact, they can. The study of an international group of researchers is published in Current Biology.

The researchers studied individuals who aimed to have a lucid dream, in which a person is aware they're dreaming. Participants were briefed in communication tools before sleep. Some also practiced with sensory stimulation, such as beeps or lights. Participants were instructed to signal researchers when they experienced a lucid dream, usually with a sequence of left-right saccades, or eye movements.

Communicating during REM sleep

REM refers to the rapid eye movement phase of sleep in which lucid dreaming can occur. The researchers used polysomnographic data to confirm that study participants had reached the REM stage of sleep.

“We found that individuals in REM sleep can interact with an experimenter and engage in real-time communication,” says senior author Ken Paller from Northwestern University. “We also showed that dreamers are capable of comprehending questions, engaging in working-memory operations and producing answers. Most people might predict that this would not be possible — that people would either wake up when asked a question or fail to answer, and certainly not comprehend a question without misconstruing it.”

Lucid dreaming

Martin Dresler1While dreams are a common experience, scientists still haven’t adequately explained them. Relying on a person's recounting of dreams is also fraught with distortions and forgotten details. So Paller and colleagues – among which Martin Dresler from the Radboudumc and Donders Institute – decided to attempt communication with people during lucid dreams.

"We aimed to communicate with dreamers who 'live' in a world that arises entirely from stored memories in the brain," Dresler explains. "If we could actually make contact, we would have a means by which we could learn more about dreams, memory, and the role of sleep in memory storage. That potentially opens the way for exciting follow-up research."

Several ways to talk to a dreamer

The paper includes four independently conducted experiments using different approaches to achieve a similar goal. Studies were conducted at the Donders Institute, Northwestern University in the US, Sorbonne University in France and Osnabrück University in Germany.

“We put the results together because we felt that the combination of results from four different labs using different approaches most convincingly attests to the reality of this phenomenon of two-way communication,” says first author Karen Konkoly from Northwestern. “In this way, we see that different means can be used to communicate."

Participant were exposed to light or sound signals, were touched on the skin (tactile stimuli), or were told spoken words. 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 it as “interactive dreaming.”

Dreaming as a treatment

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. Follow-up experiments run by members of the four research teams aim to learn more about connections between sleep and memory processing, and about how dreams may shed light on this memory processing.

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