It’s the last talk of the night at the Women’s Visionary Congress(opens in a new tab), a very Bay Area kind of conference. Amidst the yogic cushions and tea tables, volunteers are distributing little plastic baggies, each containing a gram of green leaves with a strong soporific effect. It was not California’s most famous recently legalized substance, but calea zacatechichi(opens in a new tab), an ancient and federally legal Mexican plant also known as “dream herb.”

Attendees who wish to indulge are asked to go home, brew the herb into tea — one with a taste so metallic and bitter, a plastic bear full of honey will not cut it. We will force it down, bed down for a wild night of weird dreams, and report back in the morning.

The good news for those who do not like to sup bitter tea, however, is that there is a completely substance-free way to unlock the psychedelic potential of our sleeping brains. It’s a practice used by some of history’s greatest inventors and artists to unlock their creativity. The final speaker of the evening, Jennifer Dumpert, describes herself as a "dream hacker" and dubs the drug-free experience "liminal dreaming."

Liminal dreaming is different from lucid dreaming, which means becoming aware during sleep so you can direct your brain to perform its stories however you’d like. Lucid dreaming can take an age to master, even if you chug dream herb tea every night. But liminal dreaming is simply about the moments when you drift out of and back into consciousness; it's all about trying to prolong that wild brain state as much as possible. And it is something you could try right now, just by leaning back and taking a nap.

Dumpert is the founder of the Oneironauticum(opens in a new tab), a decade-old international dream research group. Oneironauticum members all take the same vivid dream-promoting substance on the same night and compare notes; tonight, it's calea. But Liminal Dreaming(opens in a new tab), the book Dumpert just published on the term she coined, is the culmination of her life's work. It captures a fundamentally mysterious state of mind that science has barely begun to explore. Fellow author Douglas Rushkoff enthuses that it is "more accessible, sustainable and transformational than any drug or virtual reality." 

Indeed, Dumpert — who stands before the crowd in a black jumpsuit and flowing white hair, and speaks in the booming tones of a former New Yorker — is not shy about the psychoactive drug comparisons. “It's not unlike an LSD or THC kind of experience,” says Dumpert. “Liminal dreams offer a natural way to go into the stranger realms of the mind, not to mention it's completely legal, short-acting, and hangover-free.”

Having taken the trip many times at her instigation, I can confirm: She's not wrong. 

“Liminal” just means a kind of border zone. “Liminal dreaming” is less of a mouthful than the two scientific terms for the two brain states on either edge of sleep, both unfortunately coined by those florid linguists of the 19th century. There’s hypnagogia (which literally means going towards Hypnos, Greek god of sleep). And there’s its early-morning mirror state, hypnopompia (going away from Hypnos — think of those delicious stolen moments after you hit the snooze button, kind of awake and aware, kind of still living in dreamland.)

Scientifically, we’re still in the early years of a golden age of sleep. There’s so much we don’t know about our brains during six to eight hours a day. Dreams we understand least of all. We’ve known about the existence of REM sleep since 1953(opens in a new tab), when scientists first discovered that we move our eyes rapidly during certain portions of the night. But for decades, we thought dreaming only happens in REM sleep. 

It wasn’t until 2016 that a study confirmed the existence of dreams in other sleep states(opens in a new tab). (Turns out the only kind of dream that happens in REM sleep is the kind where your body is completely paralyzed, which explains sleep paralysis: It’s the brain waking up in the wrong phase of sleep, without coming up through hypnopompia first.)

Lucid dreaming, meanwhile, also eluded science until relatively recently. It was first described by Aristotle in the 4th Century BC(opens in a new tab) — but sleep science couldn’t prove its existence until Stanford University researcher Stephen LaBerge performed a groundbreaking study(opens in a new tab) in 1985: He got lucid dreamers to count to 10 with eye movements while still asleep. LaBerge’s bestselling books(opens in a new tab) kickstarted a lucid dreaming mania that has not abated yet. One lucid dreaming podcaster(opens in a new tab) describes it as the equivalent of wearing a “full-body Virtual Reality suit.”

Now here comes liminal dreaming, which is to lucid dreaming as a casual mobile game is to full-body VR. It may not last as long or be quite as involved, but it’s easier to find and accessible to all. 

Plus it has a hell of a historical track record. 

Legendary inventor Thomas Edison(opens in a new tab) and legendary artist Salvador Dali(opens in a new tab) independently arrived at the same method for getting their creative best out of hypnagogia. They’d both sit in an armchair holding a heavy object (steel balls for Edison, a key for Dali) and allow themselves to nod off — but not all the way into REM sleep. When their hands went limp, the objects would clatter to the floor, waking them up. Edison would grab a notebook, Dali would grab a sketchbook, and furious recording of their imaginings would commence.

They are far from alone in being ambassadors of the hypnagogic. Mary Shelley wrote that she got the idea for a story about an artificial man in a “waking dream” immediately after she "placed [her] head on the pillow" but "did not sleep." The late Ralph McQuarrie, the artist who visualized scripts for George Lucas, would regularly drift off in an armchair before he started painting, waiting for images to float up to his consciousness “like bubbles in champagne.”

In other words, we have liminal dreams to thank for Frankenstein, the lightbulb, The Persistence of Memory(opens in a new tab) — and the look and feel of the whole Star Wars franchise.

Here too, science is playing catch-up. Since hypnagogia doesn’t last for long — most people are in it for about five minutes before slipping into regular sleep, unless you’re a narcoleptic(opens in a new tab), in which case you proceed directly to REM — there hasn’t been much in the way of study. 

We do know that it looks really weird when you see it on an EEG monitor. All other kinds of brain states, whether waking or sleeping, settle down eventually so that they look like a steady wave. The liminal state, however, jumps around like static. This is why, when using a meditation wearable like the Muse(opens in a new tab) that gives you audio feedback from your brain, it’s hard to accidentally slip into snoozing. On the boundary of sleep, the brain gets very active, and hence very noisy.

Our bodies also get twitchy in hypnagogia. Your arms or legs might lash out suddenly, or you might wake up with a sensation that you’re falling — the infamous myoclonic jerk(opens in a new tab). We don’t know why that happens either, although the leading theory is that it’s a reflex from our ancestors, primates sleeping in trees who needed to grab branches if they fell. 

A boilerplate legal disclaimer would have to mention that people also experience “hypnagogic hallucinations(opens in a new tab),” especially auditory ones. It’s common to hear telephones that aren't ringing or voices that aren’t speaking. You might sense the shape of a stranger nearby, or something rushing towards you, which can be terrifying.

Again, we don’t know why.

“It’s almost an embarrassment, that for so many years, so little attention has been placed upon an activity that we spend a third of our lives doing,” says Dr. Guy Leschziner(opens in a new tab), clinical lead at the Sleep Disorders Centre in Guy’s Hospital, London, one of the largest sleep units in Europe. He’s also the author of a new bestseller about sleep troubles, The Nocturnal Brain: Nightmares, Neuroscience and the Secret World of Sleep(opens in a new tab). ”Until recently, we've had almost no fundamental understanding of what sleep even is, or what it’s for … we’re in an area of exponential growth of knowledge.”

It’s possible, Leschziner says, that hypnagogia is not one discrete sleep state but different parts of the brain being in different states at different times. But as if to illustrate his point, Leschziner himself has not studied hypnagogia beyond the associated disorders — those hallucinations — and was genuinely fascinated to learn about Dumpert’s positive approach.

“Well,” said the neurologist and sleep expert as we wrapped up our interview, “you’ve taught me a lot.” 

Ironically, I’d only just learned about liminal dreaming myself. Sure, I’d read about hypnagogia and hypnopompia once upon a time; they both merit a few pages in an excellent 2007 book on our everyday states of consciousness, The Head Trip(opens in a new tab). But I had not connected them to my own experience until I heard Dumpert talking about cartoons at a music festival.

This was at Lightning in a Bottle, the same place where mushroom scientist Paul Stamets(opens in a new tab) held the rapt attention of a packed house by discussing the latest research on psilocybin. Elsewhere in the TED-like lineup of talks, Dumpert was taking attendees at the Southern California festival through a guided exploration into liminal dreaming. 

We were instructed to lie down and close our eyes, to focus on various parts of our bodies and our breathing, to try to identify the nearest sound and the furthest sound. Most of the audience succeeded in slipping through. It turns out a shady tent on a hot festival afternoon, with birdsong in nearby trees and the distant thumping of subwoofers, is an excellent place to induce hypnagogia. "I'm the only speaker I know who doesn't mind if their audience falls asleep," Dumpert said. 

She was at pains to point out that liminal dreaming isn’t like regular dreaming. There’s no narrative. There’s no “you.” In normal sleep, you might go on a business trip to Mars with high-school friends and long-dead relatives and think it perfectly normal, but you’re definitely present. Liminal dreaming is egoless. You might experience flashes of light and color. All kinds of random images will show up in your head, too fast to pin down. Some of them, Dumpert says, “might look like cartoons.”

Bingo. Donald Duck, I thought. As a child I’d had general anesthetic in the dentist’s chair, and the last thing I remembered before being knocked out was an image of the Disney character strolling happily down some country lane. Ever since then, when falling asleep, that same Donald Duck would often show up in my head for a second or two. He was the herald of a series of random kaleidoscopic images that moved faster and faster, as if someone was hand-cranking a zoetrope behind my eyelids.

Suddenly it all clicked. I recognized this address. I visited every night, in fact, and sometimes after heavy lunches. 

The audio hallucinations, the primary-color images that often stood in for something else (psychiatrists call it autosymbolic phenomena), the Dali-esque melting, the drowsy sense of being pleasantly drugged, both asleep and awake at the same time. You can hear what’s going on in the world but you’re less inclined to care. This was liminal dreaming.

It can be tough to avoid slipping from hypnagogia into REM sleep if your body really needs it — and hey, who among us doesn’t need more sleep sometimes? But on this occasion, I found myself settled perfectly in the liminal zone for the remaining 20 minutes of Dumpert’s talk. It was nothing short of a revelation.