Originally published in April 2012, Reader’s Digest

The first Age of Exploration happened between the 15th and 17th centuries, when Europe’s great powers dispatched galleons to mysterious new continents. Maps once filled with sea monsters and vague sketches of broken coastline began to accumulate richness and detail. More importantly, actual encounters with exotic indigenous populations prepared the ground for what would become a profound revolution in human knowledge and self-understanding. The Age of Exploration became the Age of Enlightenment.

lucid-dream-flyingOur century marks a New Age of Exploration, into an even more mysterious frontier, with empirical discoveries that may turn out to be every bit as revolutionary as the ones that undergirded the first Age of Enlightenment. The frontier is the dreaming mind, and the new explorers are known as lucid dreamers.

The phenomenon of lucid dreaming has been known since at least the ancient Greeks. “Often when one is asleep,” Aristotle said, “there is something in consciousness which declares that what presents itself is but a dream.” Most people have had flickers of this experience in the early morning, after dozily hitting the snooze button, when they drift back into dreaming and are vaguely aware that the unfolding action isn’t quite real.

This is just the very beginning of a far more dramatic experience. It is possible to wake inside the dream itself into fully alert consciousness, with all your psychological faculties intact: reason, memory, agency. Unless this has personally happened to you it is difficult to convey how absolutely mind-blowing and radical the experience is. It isn’t the washed-out memory of a fragmented dream, with you as a detached observer. It’s you – your body, with arms and clothes and Vidal Sassoon dream hairdo blowing in the dream breeze – waking up in an actual world that is every bit as tangible and interactive and real as the world you are in now.

My first full lucid dream happened while I was researching a book on consciousness. The more I read about lucid dreaming and the more researchers I spoke with, the more I expected it to happen to me. In the middle of one normal Tuesday night I woke up in bed next to my girlfriend and looked around. Something wasn’t right. The walls shivered, as though from an earth-quake. It occurred to me I might be dreaming. As soon as the thought entered my head a wave of vertigo passed through me and I found myself standing on a cobblestone street in an old medieval town. I reached down and ran my fingers along the ground. I felt the grit between each smooth stone, felt the breath in my lungs and my heart pounding in my chest. Although I knew beyond a doubt I was dreaming, there was absolutely no difference in vividness and detail between this world and the waking one. Several people approached and I recall being exhilarated and terrified by the idea that I was about to have a conversation with some … what? – person? character? – some entity from another reality. I was so psyched I accidentally woke myself up. For the next hour I lay thunderstruck in bed, thinking about the ineffable mystery of consciousness. It had been like being beamed down to the surface of an alien planet.

There are now many books and online forums that log people’s trips to this otherworld. Some people explore the space physically, mapping the shifting terrain of the dream. Others rehearse specific activities, using the time to perfect their golf swing or karate moves. Still others fly around looking for adventure and – especially popular with young males – guilt-free safe sex.

Of course, although the usual social constraints and consequences of waking may not apply, this doesn’t mean the dream world will go along with your plans. I spend most of my lucid dreams crashing into walls, getting ignored by dream women and, once, getting beaten up. Alas, it seems that in dreams – as in life – we are at the whim of forces greater than ourselves.

For years the existence of rational consciousness in a dream was regarded as impossible. Sleep scientists dismissed reports of lucid dreaming as “micro-awakenings” – short periods of wakefulness people were confusing with dreams. But the anecdotes continued to pile up until finally, in the early ’80s, American psychophysiologist Stephen LaBerge – himself an avid lucid dreamer – devised an ingenious way to prove that lucid dreams were real.

There are several physiological giveaways to being in a dream state. One clue – twitching eyeballs – turned out to be key for LaBerge. He would fall asleep in a laboratory, wired up to an EEG (electro-encephalogram) which records neuron activity) and also an EOG (electro-oculogram, which measures eye movement), with his awake co-researcher keeping watch. In the dream world, LaBerge – trained to notice dream cues – managed to “wake up.” Fully lucid, he moved his gaze up and down, up and down in an agreed-upon pattern of eye signals. In the waking world, his co-researcher observed LaBerge’s eye movements, visible as distinctive spikes on the EOG’s sea of erratic waveforms. LaBerge had made the first-ever “transworld communication” between two distinct realities. He was effectively proving to his peers that they no longer had to collect dream reports after the act. Instead dreaming could be investigated as it happened, from the inside.

The sleep-science community was stunned. The results, according to psychologist Robert Ornstein, revealed “the possibilities of human consciousness are greater than we had thought.”

Today lucid dreaming is no longer disputed, and indeed in the past few years scientists around the world have begun to conduct more detailed experiments. Some of them are so strange and improbable they read like Hollywood scripts. In 2006 a German researcher learned to send signals from the outside world to the dream world using combinations of high and low tones delivered through earphones to dreaming subjects. While asleep, lucid dreamers – perhaps lounging on dream-world park benches – were able to hear the tones ringing in the landscape and then signal back to waking researchers with eye movements. The study established that two-way transworld communication is possible: You can get messages in, and you can get messages out.

In a more recent experiment reported in the October 2011 issue of Current Biology, researchers at Munich’s Max Planck Institute of Psychiatry passed lucid dreamers through a fMRI brain scanner (a technique that measures brain activity by mapping blood flow). As the machine recorded each of their brains in turn, the dreamers clenched and un-clenched their dream hands, even as their actual hands lay motionless. Researchers were able to see this neural activity in the brain in the exact area you would expect to see it had the subjects clenched their fists while awake. This proof-of-concept study is a big deal in the science of the mind. It provides, in the words of one of the researchers, Michael Czisch, evidence that it may be possible to “read the contents of a person’s dream.”

For researchers, lucid dreaming is an opportunity to examine the operating rules of consciousness in a “pure culture” – that is, the mind without the sights, sounds and smells of the external world getting in the way. Without these waking intrusions, scientists may better understand any number of neurobiological issues: What can we learn about the construction of memory by observing it from the outside? What part of the self “wakes up” in a dream and how is that part related to the waking self? How does dream movement compare to real-world motor activity? These questions verge on the philosophical, and yet for the first time there appears to be a concrete way to investigate them.

Even more basic are questions about the nature of this other reality. Lucid dreaming shows that the dream world is amenable to real-time scientific investigation. We can beam down into the dream and execute specific experiments in order to test the dream world’s still-unknown laws of physics, laws that are also (weirdly) psychological laws. For example, from inside the dream we can drop objects from buildings, test the consistency of dream matter, devise ways to measure how time passes. Not all dream action is random and whimsical. For example, whatever you focus on in a dream becomes more exaggerated. This is probably because whenever we attend to an element in memory, all of its associations get activated. So if we stare at a dream tree then all our ideas about trees pile up in front of us. There is no external world to keep a lid on things. Another example: Whatever we expect to happen in a dream usually does. This is because our minds are not neutral – all our learned and hard-wired assumptions about the world run free in our dreams like escaped felons.

Lucid dreaming is still not widely understood, so exploration is in its infancy. One day scientists and their dream slide rules will Morse-code reports back to their co-investigators up in the waking world. There is also the possibility that as we begin to explore our own internal processes, we may learn something about the external world too, distorted and reflected back into our dreams in ways we’ve hardly begun to appreciate. Until then the whole exploratory endeavour is thrillingly DIY – anyone can join in on the action.