December 6, 2023

Deja Vu : Scientifically Explained

  • February 10, 2011
  • 5 min read
Deja Vu : Scientifically Explained

When you see familiar faces,
But you don’t remember where they’re from,

When you’ve been particular places,
That you know you’ve never been before,

Ever had a conversation,
That you realize you’ve had before,

Have you ever talked to someone,
And you feel you know what’s coming next?
It feels pre-arranged.

– Adapted from “Deja Vu” by Iron Maiden

Déjà vu (French word meaning “already seen”) refers to feeling or illusion of having already seen, already been to or experienced something that is being experienced for the first time. In short, Déjà vu can be defined as “Familiarity without awareness”. The familiarity is usually accompanied by eeriness, strangeness, or an uncanny sense. It has been said that déjà vu affects individuals of all ages, but teenagers and young adults (between the ages 15 to 25) are more susceptible to the feeling. Déjà vu has often been described as “remembering the future” and is a very common phenomenon experienced by 70% or more of the population at least once. Its a hard experience to interpret.

Types of Déjà vu

Deja Vecu (already experienced or lived through)

– Commonest
– Sensation of having done something or having been in an identical situation before and knowing what will happen next
– Frequently connected with very banal events
– Often clearly remembered for years following their occurrence

Deja Senti (already felt)

– There are no precognitive aspects in which the person feels he or she knows in advance what will be said or done
– The episodes quickly dissipate from memory
– Firmly associated with temporal-lobe epilepsy

Deja Visite (already visited)

– Rarer
– A person visits a new place and feels that it is familiar
– It may be that the person once read a detailed account of the place and has subsequently forgotten it.

However, it can be a mixed version with a combined déjà vu effect.

Scientific theories:

Scientists at the Massachusetts Institute of Technology in Cambridge, now say they have discovered the part of the brain that is responsible for déjà vu; they say neurons in the memory centre of the brain called the hippocampus make a mental map of new places and experiences, then store them away for later use. They believe that déjà vu occurs when two events or places are very similar to each other, overlap and thus the feeling of déjà vu takes place.

Optical pathway delay: If your 2 eyes both saw the same event, but for some reason the message took just a fraction longer to reach your brain from your left eye than it does from your right, there is a chance that your brain may process the same event twice, making you feel like you’ve already seen it, even if it was only a thousandth of a second earlier. But, this theory has been antiquated after Deja Vu being reported in a blind person.

Divided Brain Function: The frontal lobes of the brain are tied to the future, the temporal lobes with the past and the limbic system with the present. In this area of the brain are the hippocampus associated with short term memory (STM) & the parahippocampal cortex associated with long term memory (LTM). Upon proper functioning, there is seamless integration between the past, present and future. However, when excessive communication between short-term and long-term memories occurs, the present may begin to feel like the past. When perceptions of the present are incorrectly filtered through the memory system of the parahippocampal gyrus and its neocortical connections (responsible for recognizing memories from the past), the present moment will feel like a past memory.

Hologram Theory: The brain, in trying to combine the information from all the senses to create a complete picture of the current experience, brings forward similar or related details from past experiences such as the same smell, sight or sound by retrieving them from long-term memory. These sensory impressions from past memories overlap with the impressions from the new experience and give it the appearance of having come from long-term memory.

Malfunctioning between the long and short-term memory circuits of the brain:
Somehow, specific information shortcuts its way from short to long-term memory storage, bypassing the usual mechanisms used for storage transfer. The details concerning this shortcut are not yet well understood. When this new, recent piece of information is drawn upon, the person thinks that the piece is coming from long-term storage and so must have come from the distant past.

Spiritual theories:

  1. Precognitive dreams
  2. Reincarnation (past-life memories)
  3. Clairvoyance (prophecy)
  4. Parallel universe (your counterpart has already experienced the same situation in parallel universe)

Common Medical Conditions Causing Deja Vu:

  1. Schizophrenia
  2. Temporal lobe epilepsy
  3. Anxiety
  4. Disassociative identity disorder

Deja Vu has also been associated with the use of psychedelic drugs

What triggered me to write about Deja vu?

One of my friends, Claimed to have a strange and supernatural experience of Deja Vu that’s really hard to explain. He claims that before visiting India, he had a dream of an Unknown place with pools at the site, concrete structure . He was in a line waiting for a turn to enter. Later during his Tour when he reached the site ” It was LOTUS temple in Delhi”, the same pool, the same structure, the same line and the people dressed in same pattern as in his dream, distributing pamplets. He suddenly felt dizzy and Nauseated , He was totally confused and shocked at this experience. How could this be possbile, he often says.

About Author

Sulabh Shrestha

Intern doctor and Medical Blogger Sulabh Shrestha


  • Does this means Time Travel is possible?

  • At Macedonian IDIVIDI-Forum, many intelligent and mentally healthy members talk about their deja-vu experiences. One member even say that the next time when he will have deja-vu, he will try to change it, to see do we, all souls, can change the future. This text is based on evil intentions to show deja-vu as symptom of mental illness. The author of this text lies.

  • I can tell you what this is from my own personal experience and i should hope somebody then goes onto tell the world as im not keen on repeating myself.

    Deja vu is triggered when you are doing something you had previously “thought” about doing before then when you are not expecting it you find yourself in that situation you were previously thinking about, as human we are not fully conscious and do not remember everything we think about on a daily basis, instead its stored in our subconscious and used when needed on “Auto-pilot” without us having to consciously extend the thought pattern.

    For example.

    On Monday i think about going for dinner with a friend, in my mind i plan this for the following Monday and have various thoughts about how the evening might pan out.
    (If you spend too long thinking about it you will be fully aware of the plan throughout the week and therefore you would not experience deja vu the following Monday)

    So as we do not remember everything we think about, if you only spent a quick moment thinking about dinner with your friend next week then forget about it, this thought is now in your subconscious so when you are at dinner with your friend the following Monday, even if it feels unplanned or a spur of the moment decision you really are only having dinner because you thought about doing it last week but forgot about it.

    So when your sat at dinner you can sense deja vu because you previously thought about having that dinner but couldnt recall the actual thought you had with it being burried deep along with all the other millions of thoughts you might have had.

    If you are good at it like me you would add this sentance whilst having the initial thought – “And at this point i will remember being sat here a week ago thinking about being sat here a week later”, then one week later when the deja vu sets in you will still get the deja vu feeling to start with but that will turn into a surprised feeling (if its your first time) as when that point happens when you said “And at this point i will remember” You will be able to remember that thought you had a week previous, you will also remember what you thought would happen next, enabling you to briefly see into the future. P.s – careful tho when i had my first prediction at the age of 16 i told my step-dad of the events that would unfold over the next few moments whilst stood with him, obviously he was surprised and sadly passed away just 2 weeks later.

    From my personal experience practising this since i was only 16 so for the past 9 years what i thought would happen next “ALWAYS” happens next so take care in what you think about as it might just happen.
    In other words – Careful what you wish for… Punk!

    I like to put it this way – What we say has a reaction, what we do has a reaction and what we think about also has a reaction (being the biggest reaction from what i have noticed), crazy how nobody discovered any of this before me but i know it all too well now.

    I can now comfortably say i can accurately predict the future at will. And also have many other abilities that i am trying to train.

    Precognition is a word i learned today, if i am the first person to have this experience of predicting the future etc then why do we already have different words to explain the actions?

    Exactly obviously im not the only one! – Feel free to contact me if you want or need more information or have any questions about anything else.

    I am really good at answering questions.

    I didn’t put all info in this short script as i left plenty of space for questioning.

    More proof that thoughts have reactions.

    This morning i was drifting back off to sleep when i suddenly thought about the tip of m6 finget being sliced off.
    Sure enough i felt the pain.

    Kind regards.

  • I dream of question papers, and I see them in the same order in the exam, at least the ones I remember! Is this a coincidence or some sort of brain wave interaction?
    I have had dreams of locations and I remember every detail about those dreams. Then, one day I experience the dream in real life. I still do not get how my brain works during sleep. But well, thats why its REM after all..a paradox!

    • Great share of Experience, Yes, science has difficulty explaining all the paradox.

  • Just last night I only got about 2-3 hours of sleep but when I woke up it was as if i slept for a full 8 hrs. I woke up 2 hrs after falling asleep and woke up thinking i was late for work and realized it was only 7:15 AM. I was ready to start my day i felt, and thought i should go back to sleep that I’d be up until 11:45PM. The sleep I was in for the 2 hours was simply amazing! I cant explain it. I did talk to an ex that i dated for 5 years via text just before going to sleep and i just dont understand. We weren’t good for each other and I broke up with her. Why did this happen?

  • I have deja-vu mostly everyday and sometimes two times a day. The reason why is because I have temporal frontal lobe seizures. I’m 26 and I also have anxiety associated with the meds I take for my seizures. I live a normal life including working and I’m working on my second degree. So I’m pretty much used to it.

  • I can’t understand while the scientific community tries to explain away deja vu, they also have scientists who study physics and alternate universe theory. Why can’t the two combine a theory and truly study it without explaining it away as a medical condition. It is a normal human experience, and stating that it is associated with some mental condition is absurd. There have been plenty of times I have experienced the situation that I have been, seen or met someone before and I can predict what will happen next, usually to my advantage I can prevent something bad or it might be a good thing, where in turn I will go with my hunch that I should say something favorable at the right moment. Too many people don’t follow their intuition like they should. Foolish!

    • I agree with you Sara,
      Often People from One Field neglect or underestimate any possibility of another’s belief or field.
      You never know whats right until you are sure.
      So combining a theory and researching on it seems very good idea.

    • Why do you claim
      “the scientific community tries to explain away deja vu,”
      If there is such a thing, the community is seeking to explain the cause / source of such reported experiences.
      NOT explain it away.

  • Had a series of intense episodes last night. Almost seems like I am trying to tell myself something through these episodes of deja vu. I start to remember the events as they are happening, people around me, things I am seeing, etc. And all the while in my mind I can hear myself talking to myself, telling me to calm down and everything is gonna be alright. I don’t know what is going on and they seem to be getting more frequent.

    • If you listen closer you will hear you! Your deepest desires are manifesting thru you simply by believing you are or could possibly exsist! It’s like looking in the mirror for the first time and taking a good look at yourself. You start to see things, accept them, then use them as best you can!

      All we are is the result of what we have thought!

      • I agree with you.

        • you wanna know what’s crazy??? I just thought about this post 3 minutes before you sent me this response. Haven’t thought about it since I posted it! You are very welcome:)

  • I seem to know all the answers to life. Life is like a connect the dot picture. I can connect every living thing to see the bigger pictures others fail to realize. Deja-Vu is us recognizing ourselves as we are in this same exact moment-in the past. We live here on earth. But there are many universes out there. You are in all of them. Looking in the sky is looking into the past. Stars may have burned out millions of years ago but the light still travels making it look like it is shining now. Same concept. Let’s take the days of a work week. You go to work everyday same schedule. One universe is Monday. The next universe is Tuesday. Earth is Wednesday. You do the same exact things at different times but in all actuality it’s at that very moment because it is then you realize it. It has happens before. You happened before.

    One day I remembered Everything! I saw myself before I knew myself and it made me see things I could not have possibly experienced in this life but I know I have. I saw ME. My true self. I will always be the same in every universe.

    • Stay off the acid or get meds for schizophrenic.

    • I want to contact you.. please respond

      • contact us at

        • I have the same experience with this “deja vu” thing.

          Indeed, since I was a kid I had it, but it went growing years after years. Here’s a list of some of my experiences that I can remember having had:

          – In 2009, I was in high school, my fourth year (equivalent to grade 10, i think). One night, I had a dream of my Math teacher giving us a lesson on ! (Factorial). I noted my dream down in a book. It was my first time seeing an exclamation point in Math. A year later, the chapter was delivered, I was scared. The same year or the next one, I had a vision of a Math examination. I scored 96% over all. People up to now still think I’m a genius.

          – This last night, I had a strange feeling of sadness. I was thinking of calling my family and check in (I live overseas), when an hour later a text came in. A relative (kid) who had been sick for the past 7 years had just passed away. The same experience happened in the past month. Somebody was hiding some thing from me. She later confessed she had an issue with someone, and a serious one.

          I have had so many different occasions where I could see strange dreams, that I noted down or told people about and that later happened, I don’t know if it’s pure coincidence or sickness, as you guys call it, but I’m looking into how to grasp control and make a good use of it. I’m willing to participate in further scientific studies if there’s any going out there. My email is
          If there is anybody willing to exchange any info about this, please dont hesitate to email me.

          • I have the same thing. My relative is a physic , and I think I have developed her abilities.

          • You mean psychic?

    • The lady one – brilliant, so smart! Never saw it that way completely..

      Sherrie – stop being so closed minded or you will never “see” or “understand” anything or anyone, including yourself.

      On another note – would you insult someone for their theory/belief in God because they have no solid proof? This is what’s wrong with our world. I would encourage you to find compassion and open mindedness and speak out of love not hate or insults.

    • May I see the articles about the other universes?

  • my gosh…i thought that i am the only one having deja vu …i remember having dejavu when i was little butr i have no clue what was ahppening…now lately with more stress and anxiety it looks like it is happening more often..i still dont know how to explain it..i am thinking maybe iam going crazy or something….lately i have been having them like 3 times in one week …..that “” seizure thing does it have to do with the fact that my daughter was diagnosed with seizure disorder….i was wondering is that the reason maybe i have some king=d od=f seizures thats why my daughter has seizures?
    please resonce anyone have anything to explain to me ‘

  • well i`ve had many a de ja vu and none of the “explanations ” explain what i saw months before in a dream.

    I think my own theory of quantum duality /entanglement is the cause.
    Yes sometimes we all experience things that are similiar to something we have done before.But sometimes people do see things in dreams quite a while before it actually happens.

    The human brain is a quantum computer.Given the fact that it operates on such levels then surely a quantum computer can have thought processes utilising quantum entanglement.
    For people who don`t know what quantum duality is, it`s when one thing can be in two places at the same time in a way.
    Basically my theory is the dream or 1ST part of a DE JA VU is operating on a positive brainwave then in the future of when the actual vision occurs is exactly the same brainwave but negatively charged thus completing the quantumly entangled process.

    • I am quite sure brain works in quantum level. In My childhood it happened manytimes that whensomething happened I knew It happened before. But I could not find any reason why I felt that. From past one year, I have covince myself the reason of it. I have seen a series of future events in dream and I remember them, when it actually happened I knew How i was know that befor. May be in childhood I was not able to remeber dream so I was wondering where did I see it !!!. I have seen somebodies home in great detail and she confirmed that I am correct. I did not visit her home. I strongly believes in quantum level past and future is overlaped and parallel univers do exists.

  • This has happened to me too! Deja Vu is happening to me many times. I am SERIOUS!!! I don’t know how to explain it! I don’t have any problems either. I am rather very smart! WHY?

    • Hargovind,
      Deja Vu does not mean you have any mental illness, it is suspected to be associated with medial lobe epilepsy but it does occur in normal human population as well.

  • Sorry for bothering, but would you mind to share your sources (specially the one about the malfunction or overlap in the long term memory and the short term memory)?

    I’ve been trying to find that for ages because that was an explanation that I saw on TV when there was not internet |:(

    Thank you!

    • The theory was mentioned in the Age of Reason

  • Your friend described intense feelings of dizzyness and nausea apon the realization. Just curious if they were ever diagnosed with any disorders? Trying to find a cause for my own experiences.

    • He hasn’t been diagnosed with any disorders and is absolutely normal after the incident. The feelings of intense dizziness is probably due to the state of confusion (inability to think with your usual speed or clarity, including feeling disoriented and having difficulty paying attention, remembering).

      • Ive had many experiences with deja vu, but the strongest was when I visired Tombstone Arizona, usa.
        I had 9 episodes of feeling I was there before in a past life, even though I lived in Canada all my life!
        The strongest sensation was when I looked at a railyard depot, and sensed that there was something missing, and could see out of the side of my eye a building. When I looked at that direction, the building wasnt there.
        Later I went to the museum, and looked at the old pictures, I saw the building that I saw previous. I asked the curator what this building was, it was the old train station that had burned down 120 yrs ago, I saw that train station.
        Tombstone id very quiet at around 9 at night and I went out to stand in the mainstreet, and their wasnt a soul around.
        I then heard piano music, and voices chatting in the street, and in the saloons as though I had been transported back. I also smelled the town. The outhouses, the horses, I heard them also, the sweat of the people, but saw nothing. This lasted for about a minute and then went deathly quiet.
        It is the most fasinating experience of my life!

        • Thank you for sharing your experience, David.

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