Lucid dreamers reveal waking brains.

Science News reports on a new method of exploring what happens to our brains when we sleep – by using self-trained lucid dreamers as guides behind the gates of Dreamland:

“The special thing about lucid dreaming is that you can get even closer to dream content and in a much more controlled and systematic fashion,” says Martin Dresler, a cognitive neuroscientist at the Donders Institute in Nijmegen, Netherlands.

Lucid dreamers who can perform assigned tasks and communicate with researchers during a dream open up tantalizing opportunities to study an otherwise untouchable realm. They are like the astronauts of the dream world, serving as envoys to the mysterious inner spaces created by slumbering minds.

So far, tests in very small groups of lucid dreamers suggest that the strange realities we visit in sleep may be experienced more like the real world than imagined ones. With more emissaries enlisted, researchers hope to probe how sleeping brains construct their elaborate, often bizarre plots and set pieces.

The rarity of lucid dreaming may be why modern science took some convincing that it’s even real. For millennia, lucid dreamers’ own testimonies were the only evidence that someone could be self-aware while catching z’s. Some scientists wondered if so-called lucid dreams were just brief waking hallucinations between bouts of sleep.

But within the last few decades, experiments have offered proof that lucid dreams are truly what they seem. It turns out, when someone in a dream purposely sweeps their gaze all the way left, then all the way right, their eyes can match those movements behind closed lids in real life. These motions, measured by electrodes near the eyes, stand out from the smaller optical jitters typical of REM sleep, when most lucid dreams happen. This gives dreamers a crude way to signal they’ve become lucid or send other messages to the outside world.

Neuroscientists are just beginning to realize the potential of that line of communication. Lucid dream research “has been enjoying a renaissance over the last decade,” says neuroscientist Tore Nielsen. He directs the Dream & Nightmare Laboratory at the Center for Advanced Research in Sleep Medicine in Montreal. “This renaissance has made it one of the cutting-edge areas of dream study.”

One research team recently deployed experienced lucid dreamers to find out whether dream imagery is more like real-life visuals or imagined ones. While asleep, six lucid dreamers moved their thumbs in either a circle or a line (or both) and traced that motion with their eyes. Participants repeated the same task while awake with their eyes open and in their imaginations with their eyes closed. People’s gazes panned jerkily when they tracked the imagined movements, as though they were viewing something in low resolution. But in dreams, people’s eyes tracked the movements smoothly just as in real life, the team reported in 2018 in Nature Communications.

“It’s been debated really all the way back to the ancient Greeks, are dreams more like imagination, or is it more like perception?” says study coauthor Benjamin Baird, a cognitive psychologist and neuroscientist at the University of Texas at Austin. “The smooth tracking data suggests that, at least in that sense, the imagery is more like perception.”

You can read tips on how to dream lucidly at the link, and read more of Nielsen’s team’s research here, in Nature Communications.