Many people have had conversations with roommates or lovers when they were half asleep, but what about dreaming? Apparently, that's possible too with researchers getting dreamers to answer their questions by moving their eyes in pre-arranged ways. The interactions could have many uses, but so far at least, this has only been shown to be possible with people in the rare lucid dream state, and not always then.

"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,” Professor Ken Paller of Northwestern University said in a statement. 

However, Paller, said; "We found that individuals in REM sleep can interact with an experimenter and engage in real-time communication. We also showed that dreamers are capable of comprehending questions, engaging in working-memory operations, and producing answers.”

“Lucid dreams” are not necessarily particularly sharp. Instead, the name refers to dreams in which the dreamer is aware they are dreaming. Sometimes, although not always, they can exert control over the course of their dream, for example traveling somewhere they have always wanted to go. Having the occasional lucid dream is common, but only a few people experience them frequently.

Amateur lucid dream enthusiasts and sleep scientists have recently been experimenting with techniques to induce lucid dreams, and some trials have produced encouraging results. 

Investigating a phenomenon that happens rarely and unpredictably is a nightmare. However, researchers are now taking the next step with people who have become sufficiently accomplished at lucid dreaming to make studies practical.

Teams at four universities independently attempted to communicate with lucid dreamers. Even with subjects who lucid dream frequently, this is time-consuming work and each institution had a tiny sample size. The researchers decided to draw their work together into a single paper with 36 subjects, making a virtue of differences in approaches such as techniques used to induce lucid dreams and whether the communication was via speech, light, or touch.

"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," Paller and co-authors write in Current Biology.

The paper reports a few participants were able to answer yes-or-no questions, tell the different sounds apart while dreaming, and even do basic calculations. Instead of speaking replies were through eye movements or facial twitches.

Upon waking one participant described the messages from experimenters coming; “Like a narrator of a movie”. Another dreamed they were in a room with flickering lights and said, “I recognized this as a [Morse-coded] signal from the outside.”

Nevertheless, success was patchy. On many nights participants failed to lucid dream at all. Even when they did, only 40 percent responded to questions, with half the answers wrong or too incoherent to assess.

Some methods produced better response rates than others. It is hoped refinement will allow deeper research, such as measuring how people's capacities change while dreaming and testing the accuracy of post-waking dream reports. The fact some people recalled giving answers different from their actual responses suggests our dream memories may be even less reliable than we thought.

The authors think the work could open doors to treating those who suffer frequent nightmares.

Ultimately the work may shed light on the great mystery of why we dream at all and perhaps open paths for therapists to guide people through dreams in ways that address waking trauma.