We remember our dreams to varying degrees, but we all dream. Even people who never remember dreaming, dream. Dreaming is detected clinically by what is called REM sleep, for rapid-eye movements. When we dream a part of our brain stem (the locus ceruleus) reduces our response to external stimuli and also is involved in inhibiting our voluntary movements below the brainstem so that we don’t act out our dreams. The pathways to the eye muscles are spared this paralyzing effect, which is why we still move them when we dream.

An ongoing question of research involves understanding exactly what the dreaming state is. It is an altered state of consciousness. We are still conscious in that we can think, we can experience our own existence, and we even can form memories. But all of these functions are altered. At a gross level, brain activity during REM and wakefulness are very similar – if you look at an EEG, for example, the electrical activity of the brain in both states is similar. As researchers are looking with more sophisticated tools, like functional MRI scans, they are finding that activity, again, is largely similar:

Results revealed activity in areas of the brain that control sight, hearing, smell, touch, balance and body movements.

One area that may be different, though, is the frontal cortex, with studies finding decreased frontal cortex activity during REM vs wakefulness. This is obviously a very quick summary of a very complicated area of neuroscience, but the bottom line for the purposes of this article is that the brain is very active when we are dreaming, we are in some sort of state of consciousness with all the basic brain functions still active, but there are differences likely dealing with the higher functions of cognition. One way to think about this is that our “reality-testing” apparatus operates differently while dreaming. We tend to be more accepting of bizarre events and thoughts in dreams that we struggle to make sense of when later remembering while awake. The dreaming you is still you but it’s a different you, similar to how the drunk you is also you but different.

All this background is leading to the question of a recent study – can we communicate with people while they are in REM sleep? Further – can they communicate back? People can certainly perceive external sensory information to some degree while dreaming. We have all had the experience of hearing or smelling something, or having an internal sensation like a full bladder, and incorporating that sensation into our dreams. This may be an evolved mechanism to keep us from waking up at every stimuli. Obviously there is some threshold where it is important to wake up, when your child is crying, or when your house is on fire, for example. The important point for our purposes now is that some level of sensory perception is possible during REM.

One other concept we have to add now is lucid dreaming – this is a state in which we are in REM sleep but we have some level of awareness that we are dreaming. This is a complex area of research also, but the short version is that this is generally an unstable state between REM and wakefulness. We are dreaming, but our consciousness is functioning more like when we are awake, so we become aware of the fact that we are dreaming. It is usually unstable in that we will tend to dream we wake up, and therefore lose the lucidity, or actually wake up and stop dreaming. Some people lucid dream more than others, and it seems to be possible to train yourself to enter the lucid state. Some studies also induce lucid dreaming by providing a sensory stimulus that the dreaming person knows ahead of time means they are dreaming.

As an aside, I have lucid dreams occasionally, and they can be a lot of fun, but yeah, they are really unstable for me and tend not to last.

Prior studies have tried to communicate with people after inducing a lucid dreaming state. However, they rely on the memory of the dreamer after waking up to report on what happened on their end. In the new study, which is actually a compilation of four studies from four different centers, the researchers tried to have the lucid dreamer communicate back to them while they are dreaming. As I said, we are mostly paralyzed while dreaming so communication is limited to moving the eyes to the right or left, or in some cases making facial grimaces. But these studies collectively show that people can communicate with the researchers while they are lucid dreaming, they can understand questions being put to them, think about them, and communicate an answer. That’s pretty cool.

Of course, this tells us about the lucid dreaming state, not the non-lucid REM state. But these states are obviously much closer than full wakefulness is to REM. (Whether or not lucid dreaming is closer to full REM vs wakefulness is an interesting question.)

These four studies are the first demonstration of real-time communication with subjects who are lucid dreaming. It will be interesting to see how far this goes, and if we can figure out a way to communicate with someone in a non-lucid dream state, and how that would even work. Further, I wonder if we could get lucid-dreaming to talk in their sleep. This happens – it is considered a parasomnia, or an atypical sleep phenomenon, but perhaps it can be induced without disrupting sleep. Having a full conversation with someone who is lucid dreaming would be interesting.

As we learn more about the underlying neurobiology of sleep, dreaming, and lucid dreaming, and combining this knowledge with newer technology for altering brain activity (transcranial magnetic stimulation, for example) we may be able to actually influence and induce these states more predictably. Activating or inhibiting certain pathways in the brain may be able to stabilize the lucid state, and allow for full spoken communication. It is interesting to speculate how far this technology can go. Could we induce a full movie-experience in a lucid state (similar to the movie Inception)?

There are potential implications beyond entertainment. Sleep is intimately involved with memory consolidation. Optimizing this process could have therapeutic implications, perhaps even mitigating or delaying dementia. This is speculative at this point, but the idea is that the dream state represents an interesting opportunity to understand how the brain produces consciousness and to directly manipulate that process, with applications beyond the research itself.