According to varying estimates, between 60 and 80 percent of the population experiences déjà vu.
The term déjà vu is French and means, literally, “already seen.” Those who have experienced the feeling describe it as an overwhelming sense of familiarity with something that shouldn’t be familiar at all.
Say, you’re discussing with a friend or family member about an important issue and then in a flash, you get the feeling that you’ve already discussed this same topic, with this same person, while you were sitting in this same spot. You even feel you know what happens next.
Déjà vu happens most often to people between 15 and 25 years of age. We tend to experience the feeling less as we age.
Is Déjà vu a medical condition?
Déjà vu has been firmly associated with temporal-lobe epilepsy. Reportedly, déjà vu can occur just before a temporal-lobe seizure.
People suffering a seizure of this kind can experience déjà vu during the actual seizure activity or in the moments between convulsions. However, around 60% to 70% of people in good health experience some form of déjà vu during their lifetime. So it’s not a diagnosable condition.
Since déjà vu occurs in individuals with and without a medical condition, there is much speculation as to how and why this phenomenon happens.
What causes Déjà vu
Experts continue to debate the precise cause of déjà vu, but most generally agree it probably relates to memory in some way.
According to Healthline, here are some of the more widely accepted theories regarding the causes of Déjà vu.
The theory of split perception suggests déjà vu happens when you see something two different times.
The first time you see something, you might take it in out of the corner of your eye or while distracted.
Your brain can begin forming a memory of what you see even with the limited amount of information you get from a brief, incomplete glance. So, you might actually take in more than you realize.
Minor brain circuit malfunctions
This theory suggests that déjà vu events may be caused by a brief electrical malfunction in the brain. Your brain falsely perceives what’s happening in the present as a memory, or something that already happened.
Another theory suggests déjà vu happens when your brain “glitches,” so to speak, and experiences a brief electrical malfunction — similar to what happens during an epileptic seizure.
Some experts believe another type of brain malfunction may cause déjà vu.
When your brain absorbs information, it generally follows a specific path from short-term memory storage to long-term memory storage. The theory suggests that, sometimes, short-term memories can take a shortcut to long-term memory storage.
This can make you feel as if you’re retrieving a long-ago memory rather than something that happened in the last second.
Another theory explains delayed processing.
You observe something, but the information you take in through your senses is transmitted to your brain along two separate routes.
One of these routes gets the information to your brain a little more rapidly than the other. This delay may be extremely insignificant, as measurable time goes, but it still leads your brain to read this single event as two different experiences.
A collection of other explanations for déjà vu also exist.
These include the belief that déjà vu relates to some kind of psychic experience, such as remembering something you’ve experienced in a previous life or a dream.
The bottom line.
According to Mindbodygreen, déjà vu remains somewhat of a mystery, but it’s typically not a cause for alarm, and rather an extraordinary (and maybe slightly creepy) phenomenon. Until we have all the answers on what’s really going on when we feel that uncanny sense of familiarity, allow the experience of déjà vu to help you foster curiosity and wonder.