While travelling on the bus recently and quietly observing from the back seat, I turned to face the front when suddenly a very bizarre feeling occurred to me. Everything felt eerily familiar: the people, the setting, the time of day, even the way I was sitting. It wasn’t just a passing resemblance to something I'd seen before — it was a powerful, almost surreal feeling that I had lived that exact moment once already. Not in a dream, not in a memory, but in some unexplainable space between past and present. Then I realized I am having a classic case of déjà vu — a feeling of having already experienced the present moment while knowing it's not true.
According to researchers, around 97% of the total population have experienced déjà vu at least once in their lifetime, and around 67% experience it regularly. I am sure you might have experienced it sometime during your life journey as well, or maybe while reading this you are having your déjà vu moment. But what causes this common yet very random experience? Is it a false memory, something strange happening in our brains, instances from our dreams, or perhaps a parallel universe?
Déjà vu comes from a French word meaning ‘already seen.’ It was coined by philosophy professor M. Boirac, who wrote a letter published in Revue Philosophique describing his own experiences of déjà vu — which, according to him, were a kind of illusionary memory. But the experience of déjà vu has been recorded dating as far back as 1st century A.D. by the ancient Roman poet Ovid, who wrote of Pythagoras claiming he remembered a past life from the Trojan War.2 He said he recognized his old shield in a temple, linking the phenomenon to the idea of reincarnation. Later, St. Augustine rejected this, saying such memories were false and possibly caused by dreams or evil spirits. Because of his influence, people avoided studying déjà vu for a long time. In recent years, it has been a source of great interest among psychologists and neuroscientists.
One study suggests that déjà vu in healthy individuals is a short memory-processing glitch that reveals how our memory system works. Some researchers propose that it occurs when new sensory information accidentally bypasses short-term memory and is incorrectly processed as long-term memory. This creates the illusion that the moment has happened before, producing a mismatch between what we perceive and what the brain recalls. Because no real memory trace exists, the experience feels familiar but lacks the detail of a true memory.
Brain imaging studies using fMRI support this idea, showing that déjà vu may arise when the brain becomes confused between familiarity and novelty. During déjà vu, a region called the anterior cingulate cortex, which helps detect conflicts in information, shows increased activity. This suggests that the brain is sending mixed signals: one indicating, “I’ve seen this before,” and another insisting, “this is new.” The resulting confusion gives rise to the uncanny sense of reliving a moment.
Déjà vu can also occur in temporal lobe epilepsy (TLE), a condition in which seizures originate in the temporal lobes — areas responsible for processing memory. These seizures involve abnormal electrical activity that affects both conscious thought and automatic responses, often accompanied by an intense feeling of déjà vu. In TLE, this sensation is believed to result from abnormal discharges in the hippocampus, amygdala, and especially the rhinal cortices, regions where stimulation can strongly evoke familiarity. The experience is usually more vivid and prolonged for individuals with TLE than healthy individuals.
Apart from scientific explanations, there are also several metaphysical beliefs about déjà vu. Some people think it’s a memory from a past life or something they dreamed about before it actually happened. Others believe it could be a brief crossover with a parallel universe, where another version of you has already lived that moment. Spiritual perspectives often see it as a sign from the universe or your higher self, showing that you’re on the right path. Maybe it is a“glitch in the matrix,” showing that reality is a simulation, like in The Matrix when Neo experiences déjà vu — moments that hint his mind exists separately from his physical body.
These are just a few of the many theories and studies on déjà vu. While scientists have explored numerous explanations, none fully capture its mystery. Such experiences show that we still have a lot to learn about the human brain and the universe. So next time you have déjà vu, just know that it could be your memory error or a manifestation of your dreams or maybe a sign that your mind might be wandering through another world, like a scene from The Matrix.
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