When I first read Konkoly et al.’s (2021) study on real-time communication with individuals during REM sleep, the findings initially seemed mildly difficult to believe. Upon hearing Dr. Gabriela Torres-Platas' presentation on the aforementioned article, I was even more intrigued. The researchers worked with lucid dreamers people who maintain awareness that they are dreaming, and demonstrated that these participants could engage in meaningful exchanges with experimenters while still asleep. Using specific eye-movement patterns or subtle muscle contractions, dreamers successfully responded to spoken questions, including simple math problems. Their brains were able to perceive external input, process it, and generate accurate responses, all without waking up.
This completely challenges the assumption that dreaming is a closed off state where no outside information gets in. Instead, Konkoly and colleagues show that REM sleep, at least in lucid dreamers, is actually surprisingly interactive. The dreaming brain can receive external cues, perform deliberate cognitive tasks, and send answers back, all without waking up (Konkoly et al., 2021).
Upon also reading Navarrete and Lewis’s (2019) commentary on another study, the story of what the sleeping brain can do became even more interesting. They describe research by Züst and colleagues showing that people can actually learn new information during deep, non REM sleep, but in a very different way. These participants were exposed to pairs of words, like a fake foreign word followed by its meaning, while they were in slow-wave sleep. If the audio played at the peaks of slow wave activity, a moment when neurons are naturally more excitable, the brain formed implicit memories of the associations (Züst et al., 2019).
When the participants woke up, they didn’t consciously remember hearing the words. They couldn’t define them or repeat them back. But they were more likely to guess the “correct” meaning in an implicit memory test. That means the sleeping brain had encoded the association without the person ever being aware of it (Navarrete & Lewis, 2019).
Reading these two papers together made me realize that sleep isn’t a single, uniform brain state. Instead, different stages have different cognitive abilities. REM sleep, especially during lucid dreaming, allows for top down cognition, intentional decisions, reasoning, and communication with the outside world. Slow wave sleep supports bottom up learning, where the brain can absorb simple associations if the timing matches its natural rhythmic peaks.
Both cases show that sleep is not an offline mode but rather an active information-processing state with selective openness to the environment. But there are limits. Konkoly’s dreamers weren’t doing difficult tasks, they were answering very simple questions, and only people who were already skilled lucid dreamers succeeded (Konkoly et al., 2021). And in the non REM vocabulary study, the learning was implicit. You won’t wake up fluent in a new language because your brain wasn’t building full concepts, it was forming tiny associative links at just the right neural moment.
Still, these findings together reshape the way we think about sleep. Instead of treating it as the opposite of consciousness, these studies show that sleep contains different kinds of consciousness and different modes of learning. In REM, especially lucid REM, the brain behaves almost like it's half awake, a hybrid state where internal and external information can blend. In non REM slow wave sleep, the brain is busily strengthening memories and, under special conditions, can even bind new ones.
What interests me most is how these two research areas might work together. For example, scientists could use targeted cues during slow wave sleep to strengthen memories, and then use lucid dreaming to examine how those memories show up or appear during a dream. Researchers could even use dream communication to study how memory processes unfold in real time while someone is asleep. We’re nowhere near sleep powered exam prep, but the previous idea that ‘the brain shuts down when you sleep’ is most definitely wrong. These papers reveal a brain that is busy, responsive, and sometimes even teachable, working quietly behind the scenes to reorganize, strengthen, and occasionally acquire new information.
References
Konkoly, K. R., Appel, K., Chabani, E., Mangiaruga, A., Gott, J., Mallett, R., Caughran, B., Witkowski, S., Whitmore, N. W., Mazurek, C. Y., Berent, J. B., Weber, F. D., Türker, B., Leu-Semenescu, S., Maranci, J.-B., Pipa, G., Arnulf, I., Oudiette, D., Dresler, M., & Paller, K. A. (2021). Real-time dialogue between experimenters and dreamers during REM sleep. Current Biology, 0(0). https://doi.org/10.1016/j.cub.2021.01.026
Navarrete, M., & Lewis, P. A. (2019). Cognition: Learning while Asleep. Current Biology, 29(5), R164–R166. https://doi.org/10.1016/j.cub.2019.01.034
Züst, M. A., Ruch, S., Wiest, R., & Henke, K. (2019). Implicit Vocabulary Learning during Sleep Is Bound to Slow-Wave Peaks. Current Biology, 29(4), 541-553.e7. https://doi.org/10.1016/j.cub.2018.12.038
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