One 1992 study on déjà vu defines it as “a dissociative phenomenon which can be characterized as a subjectively inappropriate impression of familiarity of the present with an undefined past.” It may happen when you see a scene that looks eerily familiar or hear a friend say something that you swear they’ve said before. What makes the experience of déjà vu so unnerving is that people usually can’t place exactly why the scene feels familiar or when it originally happened. It’s thought to happen less as we get older1 and appears to be associated with stress and fatigue. The phenomenon is particularly common among people with temporal-lobe epilepsy and some other psychiatric conditions, according to research on epileptic patients—with virtually all people with epilepsy having experienced déjà vu. Interestingly, the sensation often happens right before a seizure, which is known as “ictal déjà vu.” Other research has also linked it with dementia2. “Temporal lobe epilepsy, migraines, anxiety, and dissociation can be associated with more frequent and extended déjà vu experiences,” Ellis notes, adding, “Neurobiologists suggest it could be explained by parts of our brain being out of sync, and they have been able to induce déjà vu in the lab by stimulating specific cortical structures.” All that to say, déjà vu is common, and while it can be related to certain conditions, it is not a cause for alarm. “Déjà vu can warn of epilepsy or other neurological issues, but in most cases, it is a benign and mysterious experience to wonder about and enjoy,” Ellis says. With that being said, if you’re experiencing a seemingly high or bothersome amount of déjà vu experiences, talk to your doctor. That said, one 2010 study3 on déjà vu published in the journal Psychology of Motivation and Learning identified three potential mechanisms that could trigger it: This can also happen when one part of a larger scene seems familiar, but you can’t place why, “with the result that the strong sense of familiarity associated with this portion inappropriately bleeds over onto the entire scene,” the study authors say. Déjà vu has also been associated with precognitive dreaming (aka dreams that seemingly predict the future) and déjà rêvé, which translates to “already dreamed” and describes the sensation that you’ve dreamed about something before it happened in real life. Ellis adds that from a spiritual perspective, déjà vu is considered to be linked to transcendence. Spiritual author Shannon Kaiser previously told mbg something similar, explaining that frequent synchronicities, including déjà vu, can be a sign of a spiritual awakening.
