Are you curious—and sometimes maybe a bit baffled—by your dreams? Do you wake up with fragments of a dream fresh in your mind and wonder: Why did I dream that? You’re not alone. Sleep scientists wonder the same thing. We know very little about how dreaming works in the brain, about why we dream, or what function dreaming may serve. The mechanics of dreaming, and its purpose remain largely a mystery.
That’s what makes this new study so fascinating: A research team led by scientists at the ATR Computational Neuroscience Laboratory in Kyoto, Japan has used brain scans to identify the visual imagery of dreams—and garnered some new insight into the brain’s activity during dreaming. Their research used a technique called neural decoding, which uses measurements of brain activity to predict visual content. By observing brain activity during sleep, researchers hoped to be able to identify the visual content of dreams.
The study involved three adult men, who slept while researchers monitored their brain activity using MRI and EEG. In order to connect brain activity with specific imagery during dreaming, researchers woke the men in the middle of sleep and asked them to describe what they’d been seeing in their dreams just before being awakened. After giving their descriptions, the men returned to sleep. The men were awakened to report on the contents of their dreams several times per hour. For each of the three volunteers, researchers compiled more than 200 dream reports over a period of several days. These dream reports revealed that the volunteers dreamed in large part about ordinary things related to daily life—with the occasional detour into the odd or fantastical.
Researchers then divided the information from the dream reports into 20 categories representing basic visual images, including things like “car” and “computer,” “male” and “female.” After the sleep and dreaming phase of the study was complete, researchers showed the men a series of photographs that contained images representing the various categories created from their dream data. They conducted the same brain scans while the men were looking at the photographs, and compared these scans to the ones taken during sleep, paying particular attention to the areas of the brain responsible for processing visual information.
What did they find? That brain activity during dreaming is similar to the brain activity associated with processing visual information in a waking state. In simple terms, these results indicate that we “watch” our dreams in a manner similar to the way we perceive things visually while we’re awake. The patterns of neural activity were so similar that researchers were able to look at the brain activity they observed during their volunteers’ dreaming sleep and predict the visual content of their dreams with 75-80 percent accuracy.
This is some pretty cool stuff. Researchers plan to follow up this study with a similar investigation that looks specifically at dreaming during REM sleep, the stage of sleep when most of our dreaming—and many of our most emotionally resonant dreams—takes place.
Why does dream research matter? There is still so much we don’t yet know about the purpose of sleep. Despite much scientific progress, the why of sleep remains a puzzle we have yet to solve. Dreaming is an ancient and universal aspect of the sleep experience. Research into animal sleep indicates that humans are not the only species to dream, but that animals have dream states similar to ours. Understanding the mechanisms of dreaming may lead to important insights into its purpose, and to the purpose of sleep itself. Are dreams related to the learning boost that sleep appears to provide? Does dreaming play a role in the consolidation of memory that occurs during sleep? What does dreaming have to do with the processing of emotional experiences? These are just some of the questions that science is asking about dreams.
Using dreams in scientific inquiry can also reveal important insight into the workings of the brain, as in the current study, or this in this research, which used dreaming to identify—for the first time—the networks of the brain that are active in moments of self-awareness. Researchers used a phenomenon called lucid dreaming to pinpoint the neural pathways that become active during moments of self-perception, a state known as meta-consciousness. People who experience lucid dreams retain a sense of self-consciousness even in the midst of dreaming. They are aware of the fact that they are dreaming and asleep. They can manipulate their dreams and even recall memories. In a normal dream state, this sense of self-awareness is suspended, as we become immersed in the temporary “reality” of our dream state. By comparing the brain activity of lucid dreamers to the brain activity of people in a normal dream state, researchers identified the neural pathways that activate to provide us with our conscious sense of self.
Dreams are fascinating, mysterious experiences to ponder. Decoding the science behind our dreams may lead us to an ever deeper understanding of sleep, and of the mind itself.
Michael J. Breus, PhD
The Sleep Doctor™