The Psychology Of · 8 min read
How Does Deja Vu Work?
That eerie sense of having been here before — what's actually happening in your brain during déjà vu, and why is it so hard to shake?
Shola Adedeji
Published May 11, 2024
Déjà vu — French for "already seen" — refers to the uncanny feeling that a new situation or experience is somehow familiar. Almost everyone has experienced it: a fleeting certainty that you've lived this moment before, even though you know you haven't.
Déjà vu is surprisingly common. Studies suggest that approximately 60–70% of people experience it at some point in their lives, most frequently between the ages of 15 and 25. Despite how vivid it feels in the moment, it's typically brief — lasting only seconds before fading.
What's Happening in the Brain?
The most widely accepted explanation involves a temporary mismatch in the brain's memory systems. The hippocampus — the brain's memory centre — processes new information against patterns stored in long-term memory. Déjà vu may occur when the brain's familiarity detection system misfires, flagging a genuinely new experience as "known" before the explicit memory system can confirm it isn't.
Brain imaging research and studies of patients with temporal lobe epilepsy — who experience déjà vu as part of their seizures — have helped map the neural regions involved. The rhinal cortex and hippocampus appear to be the key players.
Déjà Vu and Mental Health
For most people, déjà vu is a benign curiosity. But when it occurs frequently and is accompanied by strong emotions, confusion, or a sense of unreality, it may be worth discussing with a clinician. Frequent déjà vu can be an early indicator of temporal lobe epilepsy, anxiety disorders, or depersonalisation experiences — all of which are treatable.
The occasional, fleeting déjà vu needs no intervention — it's simply the brain doing its complex work of making sense of the world.
