What Is Déjà Vu?

By: Yara Simón  | 
What is déjà vu? The term "déjà vu" means, literally, "already seen." Learn about déjà vu and theories on why it happens.
Photographer: Sebastian Kaulitzki | Agency: Dreamstime.com

The term déjà vu, also written as deja vu, is French and means, literally, "already seen." Déjà vu describes that overwhelming feeling of familiarity with something that shouldn't be familiar at all.

Say, for example, you are traveling to England for the first time. You are touring a cathedral, and you suddenly feel as if you have been in that very spot before. Or maybe you are having dinner with a group of friends, discussing some current political topic, and you have the feeling that you've already experienced this very thing — same friends, same dinner, same topic.


Read on to learn more about the different theories on why people experience déjà vu.

How Often Does Déjà Vu Happen?

Déjà vu is common and only a few seconds long. On average, people are experiencing déjà vu once a year, making it "consistent with psychological normality."


What Does a Déjà Vu Experience Feel Like?

Déjà vu, like most things, will differ from person to person. However, there's a feeling of inconsistency. As Dr. Jean Khoury, a neurologist, explains, "There’s usually an incongruence between the sense of familiarity and the fact that the situation should not feel familiar."


Why Do Déjà Vu Experiences Occur?

The phenomenon is rather complex, and déjà vu researchers have different theories about why it happens. Swiss scholar Arthur Funkhouser suggests that there are several "déjà vu experiences" and asserts that to better study the phenomenon, we need to understand the nuances between the experiences. In the examples mentioned above, Funkhouser would describe the first incidence as déjà visite ("already visited") and the second as déjà vécu ("already experienced or lived through").

As much as 70 percent of the population reports having experienced some form of déjà vu. More déjà vu incidents occur in people 15 to 25 years old than in any other age group. It often becomes less frequent as one gets older.


There is not one clear answer for these reported déjà vu experiences. There are theories that range from a mismatch in part of the brain, causing people to mistake the present for the past, to it being a "past life" experience.

Temporal Lobe Epilepsy

Scientists have firmly associated déjà vu with temporal lobe epilepsy. Reportedly, déjà vu can occur just prior to a temporal lobe seizure.

“About 60 percent of people with epilepsy have something called a focal seizure, which is in just one part of the brain," says Dr. Roderick C. Spears, a neurology specialist. This can be in the same part of the brain where memory is stored: the temporal lobe.

This theory suggests that people suffering a seizure of this kind can experience déjà vu during the actual focal seizures or in the moments between convulsions.

Wish Fulfillment

Since many types of people have experienced déjà vu — regardless of whether they have a medical condition — there is much speculation as to how and why this phenomenon happens. Several members of the psychological science field attribute déjà vu to simple fantasy or wish fulfillment.

Stress and Fatigue

Some research links déjà vu to stress and fatigue, with people with higher education and who travel a lot experiencing the phenomenon.


Déjà Vu FAQ

Why do we get déjà vu?
A person experiences déjà vu when their brain sends a signal that a particular event has happened before. Generally, it’s not something to worry about. However, some experts believe that brain dysfunctionality may cause this phenomenon.
Is déjà vu good or bad?
Déjà vu is merely a feeling and neither good or bad. Studies suggest that it may be caused when the brain is checking information that your senses are giving it.
Is déjà vu a sign of mental illness?
If déjà vu is persistent, you might be suffering from a neurological illness. It’s also a common symptom of dementia.
Is déjà vu a warning?
Déjà vu can happen all of a sudden, and while the sensation seems real for a fleeting moment, it’s not a real warning sign that something bad might happen.