At the mansion by the sea, the tiger cubs are loose again. There are dozens of them growling and toddling around this sprawling Dickensian estate. Old twisted trees reach right out into the waves, and muddy little paw prints pile up on the marble tiles.

No matter how frantically I run around herding the cubs back inside; or how insistently I call for help from the other guests of this ill-conceived wildlife refuge as they sip Champagne in the gardens, the tigers keep escaping.

In the morning, I’ll remember all of this, the stress – and the tedium too. Calls to contractors to build a fence, debating the best diet for baby tigers with my grandmother who keeps materialising to tell me she’s vegan now. All of it normal and logical ... until I realise I’m dreaming.

The strange thing is that when I wake, I don’t wake up in my bed. I wake up within the dream itself. Only now I can control it. I can build that fence, clear up our dubious permits. Hell, I can send Grandma on a long holiday. This dream isn’t unfolding around me as usual. Suddenly, I’m running the show. I’m lucid dreaming.

Since an eccentric English aristocrat named Mary Arnold-Forster chronicled her own lucid dreaming adventures during World War I (including teaching herself to “fly”), scientists have been giving this phenomenon serious study. In breakthrough research across four labs in 2021, dreamers could even answer questions posed by scientists in real time while machines monitored their sleep.

But how can you be both asleep and awake at once? What can lucid dreaming tell us about the brain and the nature of consciousness? Can you induce it? Or does it always start unexpectedly with rogue tigers and a garden party?

What is lucid dreaming?

“Dreams feel real while we’re in them. It’s only when we wake up that we realise something was actually strange.” That’s the wisdom of Leonardo DiCaprio in Christopher Nolan’s movie thriller Inception, in which thieves steal secrets from people’s minds via manufactured dreams.

But it is itself a strange feeling to realise you’re dreaming. Some people, including Elliot Page’s character in the film, will wrench themselves awake straight away, while experienced lucid dreamers say it usually heralds an adventure: suddenly they can explore and take charge of their dream. (Flying is a common pastime.) The key part is being aware you’re in a dream. Controlling what happens – directing it “like a sleepy Steven Spielberg”, as neuroscience researcher Dr Achilleas Pavlou puts it – is really a bonus.

Some people will train themselves to lucid dream using specific techniques. Others, including me, will stumble upon it accidentally. “Sometimes people have nightmares and invent it themselves as a way to get out of them,” says Ken Paller, professor of psychology and director of the Cognitive Neuroscience Program at Northwestern University who led those 2021 “dialogues” with lucid dreamers.

Only about 20 per cent of people are thought to have lucid dreams regularly but about half of us will experience at least one in our lifetime.

Aristocrat Mary Arnold-Forster was so troubled by nightmares of her sons dying during World War I that she began reminding herself during the day they were only dreams, a mantra that appeared to reach her dreaming mind too, as she suddenly found herself lucid dreaming. She chronicled her adventures (including foiling elaborate espionage plots and clothing herself in an extra-long flying dress for modesty) in her 1921 book Studies in Dreams. It lays out many early theories of dreaming since solidified by research – including that dreams likely flicker to life as our brains move memories into long-term storage overnight.

There are much earlier accounts of “dreamwalkers”, of course, from Aristotle to the ancient practice of dream yoga. But scientists didn’t have proof of lucid dreaming until the 1980s – when, in an experiment, a dreamer first signalled they were lucid by moving their eyes rapidly back and forth in an agreed-upon code while hooked up to an electroencephalogram (EEG) monitoring brain activity.

Only about 20 per cent of people are thought to have lucid dreams regularly (once a month) but about half of us will experience at least one in our lifetime. Even DiCaprio and cast mate Joseph Gordon-Levitt recalled having dreams sounding very close to lucid while working on Inception.

Still, data remains “scant because it’s so rare,” Paller says. “There’s been, like, one person who had a lucid dream in an MRI scanner. It’s hard to get people, even if they’re good at it, to have one sleeping in the lab. But now we’re getting better at the methods to help them.”

His work has also confirmed that dreamers can become lucid but not remember on waking, so the phenomenon may be more common than we think. As our lives shrank down to four walls during pandemic lockdowns, some experts reported a spike in lucid dream enthusiasts, and tips for “dream explorers” are now regularly swapped online.

But lucid dreams are not just fun – scientists believe they could help people suffering from PTSD overcome traumatic nightmares, allow elite athletes and performers to practise complex skills and reveal unique insight into the murky world of sleep and consciousness. “I mean, we still don’t really know what dreams are, we just have theories,” says Paller. “That’s why we’ve been talking to lucid dreamers.”

How do you have a lucid dream?

We spend about a third of our lives asleep and dream often – even when we don’t remember, sometimes even without falling into the REM (rapid eye movement) sleep stage most associated with dreams. But why do only some of us become lucid?

It’s always felt like an accident for me. I’ve lucid dreamed on and off throughout my life, most frequently when I was younger. I’d come up with dance choreography (sometimes staged on skyscrapers and mountaintops) or continue plotting a story I’d been thinking of in a sudden live-action cinematic. I have friends who write music in their sleep.

A simple way to check if you’re dreaming is to look at your hands. In dreams, they will often appear different, bent or elongated.

Some people describe a strange slide into a dream, descending into sleep but staying lucid the entire time, in what’s known as “wake-induced lucid dreaming” (WILD). “That’s hard to do,” says Pavlou, who has also lucid dreamed infrequently since he was a teenager. “It’s like meditation.” Instead, most people conk out and then wake up mid-action.

In Inception, dreamwalkers carry totems, physical objects they know the feel of intimately, to tell them if they are awake or asleep in a manufactured dream. This idea of a “reality check” is common among real-life lucid dreamers too (although, no, they can’t enter other people’s dreams).

A simple way to check if you’re dreaming is to look at your hands. In dreams, they will often appear different, bent or elongated. Text, too, can shift. Letters may rewrite themselves after you read them or clock hands speed up. In his research, Pavlou often has volunteers pinch their nose and try to breathe through it. “In a dream, you’ll feel the air rush in even though that’s impossible,” he says.

Still, Paller offers a lesson, courtesy of one of his research students whose own reality check failed: “He looked down at his hands and thought, oh I have an extra ghost finger, that’s interesting, and went right on dreaming. So, the key is mindfulness. It’s about really asking, ‘Am I awake?’.”

That’s why lucid dream enthusiasts are encouraged to perform little reality checks throughout the day, so the habit may carry on into their sleep.

Research shows young people and those who already recall their dreams tend to have more luck becoming lucid. But focusing on your dreams by, say, journaling or trying to return to a particular dreamscape, can increase the odds. As can waking after five hours of sleep, when you are more likely to fall into REM, and focusing on your intention to lucid dream as you fall back asleep. You can repeat it like a mantra: “Next time I’m dreaming, I’ll remember I’m dreaming.” An Australian study of 169 dreamers found these techniques worked best in combination, yielding a 17 per cent success rate for lucid dreaming over just one week.

If your dreams tend to unfold in the same settings – say in childhood classrooms (or worse still, work hallways) – you might be able to spot a glitch in the matrix. Often, Pavlou says, the best clues are deeply personal.For months after my father died, I would dream that he was alive in Tasmania on another of his elaborate bike-riding adventures, staying with old friends, sleeping under the stars, and then turning up in vivid, heartbreaking detail at the front door to tell me all about it. These days in my dreams, he’s a rare cameo. He might brush past me in a corridor suddenly. I might hear his laugh in crystal-clear detail. But that’s my reality kick. That tells me what I’ve learnt from many brutal wakings. I’m dreaming.

A “powerful moment like that”, says Pavlou, “might activate more parts of your brain and make you lucid. It’s like if you realise you’re somewhere very familiar to you but in the wrong country.”

Can you induce lucid dreams in a lab – and talk to dreamers?

If Professor Paller whispers to you in your dreams, pay attention. You may need to answer a few questions. He’s spent years “working out how to play auditory cues without waking people up”, as part of research into sleep and memory. And he used the same method to signal to dreamers that they were asleep.

Before nodding off, volunteers in his US sleep lab were trained to perform a “reality check” whenever they heard a violin sound and a red-light cue. When the EEG confirmed they’d entered REM sleep, this light and sound came on again. Some people became lucid. And some of them could then use agreed-upon signals to tell researchers.

Most of your body doesn’t move during sleep, but the eyes are a key exception. That rapid movement beneath your closed eyelids during REM is actually you looking around in a dream. In Paller’s research, dreamers would look left and right in quick succession to signal they’d become lucid. What’s more, some could use those eye signals to answer questions from scientists, live, while they slept.

“We didn’t know if that would work,” Paller says. But when simple math problems (such as 2+2) were asked of the sleepers (“not too loudly”), they appeared as part of their dreams – on a clock face or as a voice over a radio, for example. “Someone said the problem came to him inside a video game he was dreaming,” Paller says. Dreamers would try to answer back using eye movements – signalling numbers in an agreed code. While 60 per cent of these questions had no response, 18 per cent were answered correctly by the dreamers.

The results were verified across three other labs too, in Germany, the Netherlands and France. Each group used different techniques, having been researching lucid dreaming independently before joining forces. A participant with narcolepsy in France preferred using muscle twitches, smiling and frowning to answer yes and no. Those in Germany moved their eyes in morse code bursts to convey answers.

And, in separate research in the UK, Pavlou has also used sounds to induce lucid dreaming – he even used himself as his very first guinea pig to plan it. He recalls waking within a dream as he walked down a hotel corridor and hearing the first sound of the experiment ring out, signalling he was asleep. “And I thought, I’ll count each time I hear it.” He was then pulled under into the dream, “distracted by it”, before surfacing again into lucidity as the sound played another time. “Now I was on the top of a speeding train,” he laughs. “But I could hear the signal, reminding me I was dreaming.” When he woke, he checked the lab equipment and his count in the dream matched the number of times the sound had played. In his subsequent study, more than half of participants also lucid dreamed after learning to perform reality checks with this sound cue. “None of them was very experienced at this.”

Like Paller, Pavlou suspects there’s no special club of lucid dreamers decreed by genetics or some innate talent, although some researchers claim to have found links to parts of the brain associated with greater self-reflection. “I think most people can learn to do it,” he says. “Even me, I might have three lucid dreams a year on my own, but if I practice the techniques it’s much more.”

What’s happening in the brain of lucid dreamers?

The late sleep researcher Allan Hobson, of Harvard Medical School, believed that the lucid dreamer’s ability to be both awake and asleep at once could help unlock the secrets of consciousness. Inspired by the adventures of Arnold-Forster, he even successfully tried lucid dreaming himself (reporting flying as well as certain romantic escapades).

When you scan the brain of someone lucid dreaming, the areas used for critical thinking light up, distinct from the sensory and emotional fireworks mostly on display during a regular dream. In Germany, Dr Ursula Voss has been studying the brainwaves of lucid dreamers for years and found they often look more like those awake than asleep, with higher-frequency activity. Some studies have suggested that applying low-grade electrical stimulation to the scalp may induce faster brain waves of this kind and so trigger lucid dreaming, although recent research has cast doubt on the method.

Going to sleep is not like powering down your computer. The brain stays busy.

Still, researchers agree something strange is going on in the brains of lucid dreamers – perhaps even a hybrid state of consciousness somewhere between sleeping and waking. “We can say your critical capacities are better given you’ve worked out you’re dreaming,” says Paller. “But we’re not sure if you’re in a totally different state, if it’s more like waking. I think it’s still a dream state.”

Going to sleep is not like powering down your computer, after all. The brain stays busy. “And the cool thing is that it maybe doesn’t have to be all on the same page,” says Paller. “Parts may be awake, others asleep.” There is already the strange case of sleep paralysis, for example, where the mind wakes up while the body remains asleep, or sleepwalking, where people sleep as their body is roused awake.

Paller and Pavlou are now both working to take lucid dreaming studies into people’s homes using wireless monitors. Sleep research is slow and difficult in the lab, Pavlou sighs, meaning small datasets – and little sleep for researchers themselves. He’s developing a headset that guides volunteers through short reality-check training before sleep and then plays the sound cues during REM at the right volume.

Meanwhile, as Paller holds more dialogues with dreamers, he’s changing the language of communication from eye movements to a few telling sniffs. Detectors in the nostrils can pick up, say, two sharp sniffs to mean yes. “And our new experiments are about what people are seeing in the dream so [eye signals] can get in the way.”

How could lucid dreaming help with trauma – and creativity?

Opening the door to lucid dreaming for more people won’t just improve research samples. It could deepen therapeutic applications too, particularly for people suffering from PTSD and nightmares.

Therapists already encourage patients to recall such dreams or flashbacks and reframe them. “We want to do that better with lucid dreaming,” says Paller. “Even using the two-way communication during sleep to remind them they can create a better ending to the story.”

Pavlou agrees external stimuli could help shift negative dreams into positive, or reactivate certain memories. Our dreams tend to reflect our own waking stresses, he says. “That’s why there’s this psychological healing theory of dreams; that they’re like overnight therapy as your brain consolidates memories” and tries to remove the emotional sting. “And this is what happens to people with PTSD, they keep dreaming the same trauma over and over as their brain tries to consolidate the memory, but it’s not working, so it just keeps repeating.” That can leave people trapped in a wicked feedback loop, retraumatised by their own dreams.

“Some people might want to use lucid dreaming as escapism, and if you had a commercial product that could induce it you’d need to consider the ethics.”

Scientists suspect they may be able to guide the dreaming brain to solve all kinds of problems the further down the rabbit hole they go. Many of us already find inspiration in that strange twilight zone between sleep and waking, when our mind is wandering. But dreams themselves are known to fuel creativity. Albert Einstein’s theory of relativity came to him in a dream about cows; Mary Shelley’s Frankenstein sparked to life as a vivid nightmare; and Rolling Stones guitarist Keith Richards wrote the opening notes of Satisfaction somewhat mysteriously in the middle of the night after falling asleep with his guitar and waking with the opening notes on a nearby recording device.

Paller and his colleague Mark Beeman are exploring whether they “can help people along a little when they’re lucid dreaming, reminding them with [cues] of a problem they’d like to solve”.

Sleep is crucial for learning too; as memories are reactivated and filed away down deeper neural pathways. “They’re not stored one by one like bowling pins, they’re all connected,” says Paller. “So any learning during the day continues during sleep.” You might not be able to learn a whole language overnight, as is imagined in sci-fi tales such as Brave New World. But just visualising yourself performing a task fires many of the same neurons as actually doing it, cementing these connections in the neural jungle of our minds. “Formula One drivers do this visualisation all the time before they step onto the track,” Pavlou says. Lucid dreaming can kick this into even higher gear – sleep rehearsal like this has been found to improve physical skills in the real world.

Still, some researchers want a review of any potential risks from lucid dreaming too, especially if dreamers are unable to wake themselves from lucid nightmares. “We need more research,” says Pavlou. “A lot of this is still uncharted territory.” It may be that too much lucid dreaming interferes with our sleep cycle, denying us the rest our brain needs to perform repairs overnight, he says. Or, just as the characters in Inception find, perhaps it could blur the lines between dream and reality.

“Some people might want to use lucid dreaming as escapism, and if you had a commercial product that could induce it – which I think we’ll get to, or be close to, in the next 10 years – you’d need to consider the ethics, you’d need guidelines. It’s like the birth of the internet. It can be used for good and bad.”

And lucid dreaming, after all, is beyond even virtual reality. There are sights, sounds, tastes. There’s emotion.

“This is daydreaming in full HD.”

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