Déjà vu
Also called: "Already seen" · Paramnesia
A strong feeling that you have lived the present moment before, even though you know you have not. About two in three people get it. It peaks between the ages of 15 and 25.
How common
Does this happen to you?
How it works
The feeling arrives without warning. Something in the present moment seems deeply familiar, as if you have been here and heard this before. It usually lasts a few seconds4. At the same time you know the feeling is wrong. That knowing is part of the experience, and it separates déjà vu from a real memory1.
Many explanations have been proposed1. The leading one is a misfire in the brain’s familiarity system. Memory has two parts. One part signals that something is familiar. Another part retrieves the details of when and where. In déjà vu, the familiarity signal fires with no matching memory behind it1. The signal seems to come from the inner temporal lobe. Brain stimulation triggers it most often in the rhinal cortex, and less often in the hippocampus4.
A related idea is that the layout of a new scene matches the layout of a place you have seen, and the match triggers familiarity without the details. Laboratory studies using virtual scenes support this1. Déjà vu seems to happen more often with tiredness and stress6.
How common it is
Surveys find that about two-thirds of people have had déjà vu at least once1. Single surveys give figures from about 30% to 100%3. Studies differ in how they define it, whether they ask about ever having it or having it recently, and whether they rely on memory of past episodes, which is unreliable for something this brief. Rates rise with more education, income, travel, and dream recall, and they fall with age1. Episodes are most frequent between the ages of 15 and 25, then become steadily rarer3.
Is it a problem?
Ordinary déjà vu is harmless. It is a brief glitch in a system that works correctly the rest of the time.
See a doctor if déjà vu lasts minutes rather than seconds or happens many times a day. Also see a doctor if it comes with:
- a strange smell,
- a rising feeling in the stomach,
- confusion,
- a gap in awareness.
That pattern can be a temporal lobe seizure, and it is treatable5.
History and culture
The French term means “already seen”. It was coined by the philosopher Émile Boirac in 18761. The opposite experience, where a familiar place suddenly seems strange, is called jamais vu, “never seen”2.
Sources and further material
- Wikipedia Déjà vu
- kids.frontiersin.org What is Déjà vu? Frontiers for Young Minds. Gives the 15 to 25 peak and the 30% to 100% survey range.
- NCBI Non-ictal, interictal and ictal déjà vu: a systematic review and meta-analysis Frontiers in Neurology. Pooled prevalence 74%, episode length, brain regions.
- my.clevelandclinic.org Temporal Lobe Epilepsy (TLE): Causes, Symptoms & Treatment Aura signs, seizure signs and treatment of temporal lobe seizures.
- PubMed A review of the déjà vu experience Psychological Bulletin 129(3). Links déjà vu with stress and fatigue.
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Related oddities
Jamais vu
A familiar word, face or place suddenly feels strange, as if you are meeting it for the first time. It is the opposite of déjà vu, and researchers think it is rarer. In lab studies, more than half of people felt a common word turn strange after copying it about 30 times.
Hypnagogic hallucinations
Vivid images, sounds, or touches that appear while you are falling asleep or waking up. A face, a voice saying your name, a hand on your shoulder. They may be dream fragments arriving early or late, and they are usually normal.
Chronostasis
Glance at a clock and the second hand can seem to freeze for a moment before it moves. The brain hides your eye movement and stretches the first thing you see to cover the gap.
Derealization and depersonalization
The world suddenly seems flat, distant, or like a film (derealization), or you feel like you are watching yourself from outside (depersonalization). Many people have a brief episode at some point, usually under stress.