Déjà vu and the Truth of Reality

Have you ever gone somewhere and you just felt that things were intense and familiar all at the same time? Some people have this happen to the point where they don’t even see people around them anymore. This is like a memory that has a lot of detail. Maybe you can see every detail like the sunlight beating down on you, birds chirping around you.

This can be such a vivid memory, but the problem is that when this happens, it can be hard to know if this is fake or if this is the truth of reality. This can happen when you experience mental illusions of déjà vu.

The memories that we have are sacred, and one of the biggest things that Aristotle taught us is that as a child is born, they gain knowledge and experience throughout their life. This can be learning to tie their shoes, their first day of going to school, or other memories that help people work through their present-day life. Sometimes we can sit and even remember different commercials or jingles from television ads that happened a long time ago. The thing is that memories are part of our individual identities.

Most of the memories that we have are quietly in our minds, and as we go about our lives, we take our memories for granted until they fail us. Some people suffer from sicknesses like seizures or tumors that can come out of nowhere. You might be healthy for one minute and then find out that something is wrong, and it can be a time of suffering.

If you’ve experienced seizures, this is an electrical discharge in the brain, and these are sometimes followed by an “aura,” which is like a small foreshock that can last a few minutes even before the seizure happens. This can be different depending on the patient.

Some people have extreme euphoria or might even orgasm when a seizure starts. With others, it can be just a change in perspective, stress, increased heart rate, or even auditory hallucinations.

John Hughlings Jackson

It was the late 1800s when English neurologist John Hughlings Jackson first gave a name to the strange, flickering sense of familiarity that often comes just before a seizure. He called it the epileptic aura. What he noticed was that these moments weren’t just odd sensations; they carried vivid mental images, like scenes replaying from memory, even when they weren’t real. One of his patients described it as watching the past return. Another spoke of being dropped into a place that felt familiar but impossible to place.

For me, this strange pull of recognition is the most intense part of my aura. It’s not just a passing feeling, but it’s like standing in a moment I swear I’ve already lived. During stronger seizures, and sometimes for days after, it’s hard to tell what’s real anymore. I find myself questioning everything, like, “Was that a dream?” “Did that happen last week?” “Am I remembering or imagining?”

Before epilepsy came into my life, déjà vu was a rare thing. Now it visits me often, sometimes up to ten times a day. The episodes come and go quickly, lasting only as long as a heartbeat, and I’ve yet to figure out what triggers them. There’s no clear pattern. They just arrive, brief, powerful, and disorienting, and then vanish.

For many of the 50 million people across the world who live with epilepsy, memory problems and emotional struggles are part of the long-term reality. And I won’t lie, sometimes I do wonder what might happen if I lose my grip on what’s real altogether. This blending of memory, imagination, and sensation feels like walking a tightrope some days. But learning more about déjà vu, about the strange crossroads between mind and memory, helps me stay grounded. It reminds me that even when my inner world feels like it’s shifting, there’s always a path back to what’s real. Even from that “strange place.”

Catch 22

Joseph Heller in “Catch 22” said that déjà vu was “a weird, occult sensation of having experienced the identical situation before in some prior time or existence.” Comedian Peter Cook had his own spin on it, humorously repeating the phrase, “this has happened before,” to capture the odd loop déjà vu can feel like.

The phrase itself comes from French, meaning “already seen.” It’s one of several strange memory experiences that leave us questioning what’s real and what isn’t. According to research from over 50 studies, around two-thirds of people say they’ve felt it at least once. For most, it’s just a passing glitch in memory like something curious, but not something that lingers.

But there’s a deeper, more unsettling cousin to déjà vu: déjà vécu. This one doesn’t just feel like a moment you’ve seen before. It feels like you’ve lived through entire events before, even down to every word, every gesture. It’s not quick, and it doesn’t fade the way déjà vu usually does. Even more troubling is that people who experience déjà vécu often can’t separate illusion from reality.

What sets déjà vu apart from déjà vécu is awareness. Most of us know, even in the moment, that our brain is playing tricks on us. There’s a kind of internal alarm that says, “This feels familiar, but it can’t be real.” With déjà vécu, that filter is gone. The brain stops checking and just accepts the illusion as fact.

Professor Chris Moulin, one of the leading researchers on this topic, recalls working at a memory clinic in Bath, England, when he met a patient whose case left a lasting impression. Back in 2000, Moulin received a referral for an 80-year-old retired engineer known only as AKP. The man had dementia, and as his brain changed, he began experiencing chronic déjà vécu—so much so that it ruled his daily life.

AKP had stopped watching TV and reading the paper because he believed he already knew how everything ended. His wife said it felt like he thought every moment had happened already. When he came to the clinic, he resisted even walking through the doors, convinced he’d already been there. On meeting Moulin for the first time, AKP insisted he remembered their previous conversations in detail, like conversations that had never happened.

Still, there was a strange kind of self-awareness tucked into his confusion. When asked how he could predict the ending of a TV show he’d never seen, AKP would simply reply, “How should I know? I have a memory problem.”

This is the strange tug-of-war that defines the déjà vu experience. Even hallucinations, like a vivid picnic in a wheat field, can feel as real as any personal memory, even when we know they’re not. Moulin explains that déjà vu often starts with a sense of familiarity. But sometimes, something more happens, like an image, or a moment takes on the weight of memory. The mind treats it like an accurate recollection, even when logic says it can’t be.

“There’s a feeling of pastness,” Moulin says. “It’s not just that something feels familiar, but it feels like a real memory returning.” And when that happens, even fiction can feel as solid as fact.

Some of the patients Professor Chris Moulin has worked with show a troubling trait known as “anosognosia.” In plain terms, it means they either don’t realize they’re dealing with a memory disorder, or they struggle to tell the difference between what really happened and what their mind created. Moulin recalls speaking with one woman who described her déjà vu as feeling exactly like her own real memories. In her mind, she’d flown into helicopters and lived through all sorts of extraordinary moments. These weren’t casual thoughts, but these memories felt real to her, and she spent long stretches trying to figure out if they had actually happened.

After meeting AKP, the elderly man who lived in a near-constant state of déjà vécu, Moulin became more curious about how these surreal experiences form. What is it, he wondered, that makes the brain feel so sure of something that never happened? He noticed that while people often talk about déjà vu, there wasn’t much reliable research exploring what caused it. So, he and his colleagues at the Language and Memory Lab at the University of Leeds decided to dive into it.

They focused their research on people with epilepsy and severe memory issues, hoping that by understanding their minds, they could uncover clues about why healthy brains also experience déjà vu. What they were really chasing wasn’t just an answer to a memory glitch, but a deeper question about how consciousness works.

But studying déjà vu in a lab is like trying to catch fog in your hands. These moments come and go in a flash. They’re unpredictable, hard to reproduce, and impossible to summon on demand. That left Moulin and his team with a tricky challenge: how do you study something that disappears the second you try to hold onto it?

Emile Boirac

Back in the late 1800s, a French philosopher named Émile Boirac tried to describe a strange experience he had. He found himself walking through a city he’d never been to before, yet everything felt eerily familiar, as if he’d already been there. To make sense of it, Boirac wrote to a philosophy journal and introduced a term that still sticks with us today: déjà vu, or “already seen.” His guess at the time was that this feeling came from a forgotten memory being stirred up by the present moment, like a faint mental echo.

That idea isn’t so far-fetched, and even today, it holds weight. But as time went on, other theories about déjà vu took us into stranger territory.

In the early 1900s, Sigmund Freud explored déjà vu experiences in his book The Psychopathology of Everyday Life. Most people remember that book for introducing the “Freudian slip,” but Freud also included a story about a woman who walked into her friend’s house for the first time and somehow knew what every room would look like before stepping inside. Today, we’d call that déjà visité, which is a sensation of having visited a place before, even though you haven’t.

Freud believed this wasn’t random. He thought it was the result of a hidden fantasy bubbling up when a person’s surroundings matched an unconscious desire. While parts of that theory still hang around in psychology, Freud, as he often did, took things too far. At one point, he even suggested that déjà vu might link back to a memory of a person’s time in the womb or an early fixation on the mother’s body. Understandably, that idea hasn’t aged well.

In 1983, South African neuropsychiatrist Vernon Neppe stepped in to give the experience a more grounded definition. He described déjà vu as the “inappropriate impression of familiarity” during a moment that shouldn’t feel familiar. Neppe also identified twenty different types of déjà vu experiences. Not all of them involve sight. There’s déjà entendu (already heard), déjà senti (already felt), and even cases of people born blind who still claim to have déjà vu sensations.

Unfortunately, thanks in part to Freud’s psychological explanations and their more extreme interpretations, déjà vu was eventually lumped in with paranormal claims. A Gallup poll in the early ’90s listed déjà vu alongside astrology, alien encounters, and ghosts. The sense of familiarity we sometimes feel became a playground for fringe ideas about ESP, time travel, and past lives.

That fringe status has held déjà vu back in scientific research circles for decades. Many researchers simply wrote it off as something too strange or unprovable to study seriously. Only recently, over a century after Boirac first named the phenomenon, are scientists beginning to peel back the layers and understand how our brains might be glitching like a momentarily misfiring computer, creating the illusion of a memory where none exists.

As neuroscientist Read Montague once put it, we’re all running on “wet computers.” Sometimes those machines make mistakes. And when they do, we might just find ourselves standing in a moment we’ve never lived but somehow remember anyway.

Hippocampus

The hippocampus is one of the most beautiful and vital parts of the brain. Shaped like a curled seahorse and nestled deep near the base of the brain on both sides, it plays a powerful role in how we store and recall our life experiences. The name itself comes from the Greek word for “seahorse,” and the visual resemblance is easy to see once you look at it.

It’s only been in the past few decades that researchers have started to truly understand the role this delicate structure plays. Back in the 1970s, a cognitive neuroscientist named Endel Tulving changed how we think about memory. He proposed that our memories fall into two main groups. The first group, called semantic memories, is general facts we know, things like the capital of a country or the date of a historical event. These types of memories don’t really carry personal meaning. The second group, which he called episodic memories, are the ones tied to specific life experiences, but like the time you visited a museum on a class trip when you were eleven. These memories help shape your sense of self.

With better brain imaging tools, Tulving found that episodic memories are not stored in one neat spot. Instead, the brain scatters the pieces across different regions and then pulls them together like a puzzle when you remember something. He believed this act of remembering was a kind of time travel, almost like mentally revisiting the moment all over again.

Most of these pieces come together in and around the hippocampus. It acts like a highly organized librarian. After information is processed by other areas of the brain, the hippocampus takes over to sort, link, and catalog everything into memory. It groups experiences by what’s familiar, like putting all your memories of visiting art galleries into one mental folder. These associations help you bring up the right memory at the right time later on.

This connection between memory and déjà vu is no coincidence. Many people who experience frequent déjà vu also have epilepsy that begins in the temporal lobe, which is the same part of the brain tied closely to memory and sensory processing. My own epilepsy is located there. This region, which sits just above the ear, is deeply involved in managing incoming information, making sense of what we hear, see, and feel. It’s also where many seizures that trigger déjà vu tend to originate.

Professor Alan S. Brown

Professor Alan S. Brown, who wrote The Déjà Vu Experience, proposed over 30 possible explanations for why déjà vu might happen. He suggested that anything from neurological disruptions to something as ordinary as being tired or overstimulated could be enough to trigger the sensation. In my own case, déjà vu became a regular experience after my brain surgery. I was mostly confined indoors, heavily medicated, and living in a hazy dreamlike state where sleep, pain relief, and reruns of old movies blurred together. That mental fog, combined with fatigue and overexposure to familiar sights and sounds, might have opened the door for déjà vu to appear more often than usual.

Brown also revisited an older theory known as divided perception, first introduced in the 1930s by psychologist Edward Titchener. Titchener believed that when our attention is split, like being distracted by a storefront right before stepping into the street, our brain might briefly process a moment without us fully noticing it. Then, when we focus again, it feels like we’re repeating something we already did. It’s not that we actually lived the moment twice, but our brain logged it into two pieces, creating the illusion of repetition.

Another theory from the 1960s came from Dr. Robert Efron, who worked with veterans. He suggested that the brain usually attaches a sort of timestamp to events to help us know when they occurred. But if that system lags for even a second, the brain might process an event and mark it as something that already happened, leading to the odd feeling that we’re reliving something even though it’s brand new.

Even with these different perspectives, both Brown and another leading researcher, Chris Moulin, agree that the hippocampus may be the key to it all. Since this part of the brain is so deeply involved in organizing memories by familiarity, it might be misfiring or getting “confused” during a déjà vu episode.

Brown believes these feelings are often triggered by unusual activity in the part of the brain that evaluates familiarity, most likely near the hippocampus, and often on the right side. Ironically, that’s exactly where a small lemon-shaped void sits in my brain, an area surgically removed during treatment for my epilepsy. That missing piece might be part of the reason why I experience déjà vu so intensely. It’s as if my mind is trying to match new moments with memories that no longer exist, constantly creating echoes in a room that’s no longer there.

Memory Glitches or Something More?

At Duke University, psychologist Alan Brown teamed up with Elizabeth Marsh to run an experiment that gave some insight into how déjà vu might work. Their idea was to see if the brain could confuse two memories just because they looked or felt similar. To test it, students from Duke and Southern Methodist University were shown a quick slideshow of campus photos, common places like dorms, libraries, and classrooms. A week later, they saw some of those same photos again, but with new ones slipped in, this time from the other school’s campus.

Even though some images were from unfamiliar locations, a number of students said they felt like they’d been there before. Why? Probably because a single element, like the way the chairs were arranged, or the color of the walls, was enough to spark a feeling of familiarity. This helped Brown and Marsh support their theory that déjà vu may happen when the brain grabs onto a detail and misfiles it as a personal memory.

Around the same time, Chris Moulin and Akira O’Connor from the University of Leeds were able to recreate déjà vu in a lab setting. They were studying how memory recall actually happens, how the brain checks if something really happened or just feels like it did.

Moulin believes that déjà vu is a sudden overreaction to something that feels familiar. The brain is constantly scanning for things it recognizes. But in moments of stress or even heightened awareness, it might misfire, triggering a false alarm that says, “Hey, we’ve seen this before!” Then another part of the brain kicks in to argue, “No, we haven’t,” and the confusion creates that eerie feeling we call déjà vu.

He compares the brain’s memory process to a sliding scale, from fully accurate memory at one end to extreme, ongoing déjà vécu at the other. Déjà vu sits somewhere in between, a momentary glitch rather than a full breakdown. But for people with neurological challenges like those with temporal lobe epilepsy, that tiny glitch can become a trap. Moulin describes it as being stuck in a mental loop, with no off-ramp back to reality. And that’s exactly what it can feel like when your brain doesn’t give you the signal that says, “This is new.”

But what about people without epilepsy? Why do so many healthy people experience déjà vu, too?

Brown says it’s pretty normal. Most people might feel it once or twice a year, maybe more if they’re tired, stressed, or in a relaxed state. It tends to happen indoors, often while hanging out with friends or during downtime. For some, it happens more often in the evening or over the weekend. The experience usually doesn’t last long, just a few seconds but it’s long enough to make people pause and wonder.

Some studies suggest there may even be a connection between dream recall and déjà vu. Brown has also found that certain personality traits may increase the likelihood of experiencing them. Younger people, frequent travelers, and those with more liberal or open-minded perspectives report déjà vu more often. Brown believes this makes sense, and well-traveled folks are more likely to stumble across similar places, and open-minded people may be more willing to admit to having strange mental moments.

Age is a more curious part of the equation. Normally, we associate forgetfulness or memory quirks with aging, but déjà vu seems to happen more often in younger people. Brown suspects that younger adults may simply be more in tune with their internal worlds and more likely to explore unusual experiences rather than dismiss them.

Back in the 1940s, a student named Morton Leeds kept a detailed journal of his own déjà vu experiences, where he recorded 144 in a single year. One of them was so intense that he said it almost made him physically sick. I get that. After my recent seizures, I’ve had similar moments where the déjà vu doesn’t just feel strange, but it leaves me feeling like my mind is being stretched too thin. I’ve had dream fragments crash into my thoughts out of nowhere. Conversations I’ve never had feel instantly familiar. Even doing something as simple as boiling water or reading a newspaper headline can feel like I’m watching a scene I’ve lived through a hundred times.

Sometimes these moments fade quickly. At other times, they leave a residue I can’t shake for hours. The repetition gets exhausting, like flipping through an album where every photo is the same. It’s mentally draining and emotionally hard to explain to someone who hasn’t lived it.

And still, I keep trying to figure it out. Finding clarity in how and why déjà vu happens feels like my best shot at understanding what’s happening in my brain and maybe easing some of the anxiety around it.

Final Thoughts

Last night, just before finishing this piece, I had another seizure. As it happened, I was certain, absolutely convinced, that I had already written the ending to this article. In my mind, the words were right there, laid out and done. But when I woke up the next day and pulled the document up, that part of the page was blank. Nothing was there. Another illusion.

And now, here I am, writing this for real. Or maybe writing it again. Either way, it’s like déjà vu all over again.