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As this article reports, “déjà vu experiences that are unusually prolonged or frequent, or in association with other symptoms such as hallucinations, may be an indicator of neurological or psychiatric illness“. Apparently, Déjà Vu (DV) are experienced by many people. This french expression, which literally means “already seen“, actually refers to a really interesting topic. I’ve decided to put together some information about that, feel free to leave a comment if you’d like to share your opinion.
Wikipedia defines the DV as “the phenomenon of having the strong sensation that an event or experience currently being experienced, has already been experienced in the past, whether it has actually happened or not“. The origin of such phenomenon is not clear, even if recent research found that it might be correlated to improper electrical discharges taking place in the human brain. A DV event can be non-pathological (experienced by healthy subjects) or pathological (usually associated with temporal lobe epilepsy). In the latter case, the erroneous sensation of memory is intended to result from a neurological anomaly. Another theory attributes the DV feeling to having dreamt about a similar situation or place, and forgetting about it until one, while awake, seems to be mysteriously reminded of the situation or the place.
We probably don’t know that epilepsy is far more common than one might imagine. Most people suffer regular mild epileptic episodes, such as that of the so-called hypnic jerk (also called hypnagogic jerk, sleep start, sleep twitch or night start) . As god wiki says, the hypnic jerk is the “involuntary twitch which occurs just as a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the jump experienced by a person when startled, often accompanied by a falling sensation. Hypnic jerks are associated with a rapid heartbeat, quickened breathing, sweat, and sometimes a peculiar sensory feeling of shock or falling into the void“.
Associated with epilepsy is also the DV’s opposite, the Jamais Vu (JV) phenomenon. Literally “never seen“, the JV is experienced when a person momentarily does not recognize a word, person, or place that they already know. Such condition provokes a sense of eeriness for the subject, who feel as if they were seeing the situation for the first time (despite rationally knowing that it is not so).