Déjà vu is a French term that means “already seen.” It describes the feeling that a person has already experienced the exact moment they are currently living through or that an unfamiliar place somehow feels familiar.
It is the unusual sensation of thinking, “I have been in this situation before.” Déjà vu is generally not considered a health problem and may be associated with fatigue or anxiety.
However, when déjà vu happens frequently, lasts longer than usual, or occurs with symptoms such as headaches, fear, or loss of awareness, it may be associated with a neurological condition such as migraine or epilepsy. A neurologist should be consulted for an evaluation if this occurs.
Why it happens
Although these theories can be complex, they may help explain why déjà vu happens:
1. Accidental brain activation
This theory suggests that when the brain sees a familiar scene, it:
- Searches stored memories for similar details
- Signals that the situation is familiar when it finds a matching memory
However, this process may not work correctly, causing the brain to mistake a new situation for one that has happened before.
2. Memory malfunction
This is one of the oldest theories about déjà vu. Researchers believe the brain may skip over short-term memory and immediately access older memories, causing the two types of memory to become confused.
As a result, a recent memory that is still being formed may be interpreted as an older memory. This can create the feeling that the same situation has already happened before.
3. Dual processing
This theory is related to how the brain processes information received through the senses. Under normal conditions, the temporal lobe in the left hemisphere separates and analyzes incoming information before sending it to the right hemisphere, after which the information returns to the left hemisphere.
This means that each piece of information passes through the left side of the brain twice. When the second passage is delayed, the brain may have difficulty processing the information and may mistakenly interpret it as a memory from the past.
4. Memories from incorrect sources
The brain stores vivid memories from many sources, including daily life, movies, and books. This theory suggests that déjà vu may occur when the brain recognizes a situation that resembles something previously seen or read and confuses it with an event that actually happened in real life.
What it can mean
In most cases, déjà vu is associated with fatigue, anxiety, or stress. However, when it happens frequently or occurs with loss of awareness, feelings such as fear, anger, or euphoria, or symptoms such as a rapid heartbeat, pale skin, or repetitive body movements, it may indicate an epileptic seizure.
Déjà vu may also occur as part of a migraine attack, either before or during the headache. According to the American Migraine Foundation, migraine aura often causes visual symptoms such as flashing lights, spots, zigzag patterns, or other visual disturbances.
When epilepsy or migraine is suspected, it is important to consult a neurologist for a detailed evaluation and appropriate treatment.