Answering or adding up yes or no questions doesn’t seem difficult – but a group of volunteers managed to do it in their sleep by listening to and understanding the cues given to them outside of the dreams. It was the first time that two-way communication, inside and outside of the dream, was established: they are “interactive dreams,” as one reads in a study published in the journal Current Biology. “We have shown that it is possible to perceive and answer complex questions during the dream, and that dreamers can answer these questions correctly without first knowing what they are being asked,” say the researchers.
The study was carried out in four laboratories (in the USA, Germany, France and the Netherlands) with 36 participants. The researchers found that these dreamers were able to perform simple mathematical calculations (like “eight minus six?”), Answer yes or no questions, and distinguish sensory stimuli – all while sleeping. To answer them, they used eye movements, smiles, facial movements or even patterns similar to Morse code (in the German laboratory).
As neuroscientist Ken Paller explains to PUBLIC, “people cannot speak or move their bodies during REM sleep,” which is why the sleeping volunteers used these signals. The REM (Rapid Eye Movement) corresponds to the phase of sleep, which is most associated with the dream, in which the eyes, as the name suggests, move quickly. At this point, almost all muscles are paralyzed, but the brain is in an active state.
Participant Christopher Y. Mazurek and the electrical signals generated during sleep Northwestern University / C. Mazurek
“We found that people in REM sleep can interact with the researcher and communicate normally in real time,” said Ken Paller of Northwestern University (Illinois, USA), one of the study’s authors.
It’s like trying to talk to an astronaut in another world, the scientists write. “But in this case the world consists entirely of memories that are stored in the brain.”
In this case, the scientists decided to communicate with people who were in a state of lucid dreaming, a “rare phenomenon” in which some level of consciousness or control is maintained during sleep. The Greek philosopher Aristotle was one of the first to write about these types of dreams. According to a 2016 study, around 55% of adults say they have had at least one lucid dream in their life. Of the three dozen participants, one had narcolepsy and frequent lucid dreams. Others also had lucid dreams more often, others less so – the criterion was to remember at least one dream a week.
While the volunteers were still awake, the researchers first explained what lucid dreams were and said they would give them clues through words, sounds, lights, or the tap of their fingers. Dreamers were asked to try to mark the moment when they entered a lucid dream by moving their eyes in a certain way: for example, three times to the left. Once they fell asleep, the scientists monitored their brain activity, eye movement, and facial muscle contractions.
Participant Christopher Y. Mazurek before a sleep session. The electrodes are used to measure your facial movements while you sleep at Northwestern University / C. Mazurek
Of the 158 questions asked of dreamers, 18.6% of the correct answers were received. Only 3.2% were wrong answers, 17.7% were dubious answers. In most cases (60.8%) no answer was given. As this data shows, communication is difficult – but not impossible.
After waking up, they were asked to tell what happened in their dreams. Some even remembered the questions asked, and in one case the participant said the question came from a radio in a car. To others, it seemed like a voice telling their dreams “like it was a movie”. “I was fighting elves when I felt the signal with the touch of my fingers. I remember being surprised to be able to do so many things at the same time, ”reported one of the participants. Ken Paller says that another student dreamed of being in the middle of a math class.
The signs of electroencephalography of the participant Christopher Y. Mazurek. The zigzag pattern of red lines shows eye movement when you indicate you have been dreaming and the answer “two” to the question “How much is eight minus six?” K. Konkoly (animation by J. Stoughton)
The information given during sleep was always “new”, questions that had not been mentioned before. This study led the researchers to conclude that “the participants retained some of their cognitive abilities while sleeping”: they remembered the pre-sleep instructions, applied them as they received new information, and answered the questions externally. and used memory operations to solve math problems and respond about memories of her life.
Researcher Karen Konkoly Northwestern University / K. Konkoly
In addition to the North American University, experiments were carried out independently at the Sorbonne (France), Osnabrück University (Germany) and the Radboud University Medical Center (Netherlands). “We decided to combine the results because the combination of four independent laboratories using similar techniques confirms the reality of this phenomenon, which is two-way communication,” says author Karen Konkoly of Northwestern University. “In this way we can also see that different means of communication can be used.”
Neuroscientist Ken Paller says that lucid dreams can have some risks – that have yet to be investigated – and that some people who have these dreams “feel like it’s a less peaceful sleep”. During this investigation, a method was developed to make it easier for people to have lucid dreams. This method is available in an application (in English and for Android only) that anyone can try at home. It only takes 20 minutes of “training” before you fall asleep.
There is still a lot to explain in the scientific world of dreams. The memory of dreams is unreliable: “Almost everything we know about dreams is based on the reports of the person who is already awake and who may be misrepresented,” said the science magazine Konkoly with Forgotten Parts. It was already known that one-way communication was possible – how to incorporate the sound of the alarm clock into the dream – but in other studies communication was done later, with participants already awake.
The study also suggests that it is possible to learn while you sleep, as participants agreed to know information outside of the dream that they did not have before falling asleep. In the future, this method can be useful for treating trauma, anxiety, and depression.