Why Do People Experience Déjà Vu?
If you’ve ever thought, “I’ve done or seen this before,” in the middle of a new experience, it might have been the neurological phenomenon known as déjà vu. While it’s fairly common, it occurs in some people more than others—and although it’s typically harmless, frequent experiences of it are associated with some neurological conditions.
What does déjà vu feel like?
This term is French for “already seen.” The dictionary definition is “a feeling of having already experienced the present situation.” Usually very brief and fleeting, this odd sense can feel unsettling and inexplicable because your brain is telling you that you recognize a place, scene, or event that you know is brand-new to you. It’s not just a feeling of familiarity, but also the knowledge that the familiarity is false.
It typically occurs on an irregular basis, but déjà vu can leave some with such a strange sensation that they remember it for months or years. The sudden feeling of familiarity during déjà vu could be linked to nerve cell activity in a healthy brain, as the brain processes new information and tries to connect it to existing memories.
One study reports that 97% of the population have experienced déjà vu at least once in their lifetime, and 67% experience it multiple times.
It’s also been found to happen more frequently in those between the ages of 15 and 25, with the frequency of the experience tapering off with age. While all aspects of this phenomenon aren’t fully understood yet, researchers have identified some trends and potential causes.
What causes déjà vu?
There are a few theories about the cause of déjà vu according to literature and cultural or religious traditions. These theories may involve different concepts ranging from reincarnation to unconscious memories.
In an academic review of research on the topic, a connection between frequent déjà vu and certain neurological conditions, such as temporal lobe epilepsy, has been made. In individuals with this condition, a sense of déjà vu may precede the onset of a seizure. People who experience focal seizures may suddenly feel an intense déjà vu before the seizures occur.
In neurologically healthy individuals, the underlying causes are still unknown. Some various theories, connections, and findings include:
Less gray matter
One study compared gray matter volume in the brain between healthy subjects that did and did not experience déjà vu. It found that the volume was inversely correlated with the frequency of the phenomenon. In other words, those who had less gray matter volume in a certain part of the brain tended to experience déjà vu more frequently.
A brief lag in neural transmission
Other research postulates that it’s caused by a brief change in the normal speed of neural transmission. The result of this temporary lag is “a slightly longer separation between identical messages received from two separate pathways.” You can think of this as the brain taking an extra second to process a memory it just made. So when it does, you recognize it as a past memory.
A brief split in a perceptual experience
The research cited above also proposed that déjà vu could be caused by “a brief split in a continuous perceptual experience that is caused by distractions and gives the impression of two separate perceptual events.” If your brain gets distracted for a split second while you’re taking in a new experience and then returns to the experience, it might process the first moments of it as separate—a past memory.
Who is more likely to experience déjà vu?
Again, researchers are still in the process of discovering why some people may experience déjà vu more than others if they don’t have a neurological condition.
One study noted a potential correlation between more frequent déjà vu and the condition of anxiety.
There may also be a link to stress and tiredness since both can affect short-term or long-term memory. Interestingly, another frequently cited study found a correlation between more frequent déjà vu and people who:
- Tend to remember their dreams
- Are well-educated and/or have a high income
- Travel frequently
- Are politically liberal
Yet another study found a link between frequent déjà vu and the use of the flu medications amantadine and phenylpropanolamine—including one case study where a person had several instances of déjà vu per hour until they stopped taking the medication. In other words, this relatively mysterious occurrence in the brains of those who do not have a neurological condition may be linked to a variety of causes or contributing factors. More research is necessary in order to know for sure.
When is déjà vu a cause for concern?
Déjà vu seems to be a relatively common, harmless phenomenon in most cases. However, there are some instances when it may be a sign of a condition that requires medical attention. According to the Cleveland Clinic, if you’re experiencing déjà vu as often as several times a month, you may want to consult a neurologist. This is especially true if it’s accompanied by unusual dream-like memories, a loss of consciousness, a racing heart, or a feeling of fear. In a case like this, it’s possible that an underlying neurological condition may be at play.
Even if you only experience déjà vu occasionally and it's not accompanied by other symptoms, it can be an unsettling, uncomfortable feeling. Some people in this situation may find it helpful to speak with a therapist about it. Simply vocalizing the experience to share it with someone else may feel calming, and a counselor can help you address any fears that may be associated with it. In addition, if a condition like anxiety or depression is causing you to react more strongly to an occurrence like this, a mental health professional can help you manage your symptoms.
Seeking therapy can be a unique process that depends on the individual. Some feel more comfortable connecting virtually with a therapist from their home. Since research suggests that this format can provide similar benefits to in-person sessions, it’s a viable option for those who prefer it. A virtual therapy platform like BetterHelp can match you with a therapist who you can speak with via phone, video, or chat to address the concerns and challenges you may be facing. Or, you can seek a provider in your area for face-to-face sessions. It’s typically best to choose the method that feels right for you.
Takeaway
In most cases, déjà vu is a normal human experience and is not cause for alarm. About two-thirds of people or more experience it at least once in their lives. If it happens more frequently or is accompanied by other symptoms, you may want to consult a neurologist for advice, diagnosis, or treatment. If it happens infrequently and without other symptoms but causes feelings of discomfort or anxiety, speaking with a therapist may be helpful.
Why does déjà vu happen?
The exact cause of déjà vu is still unknown; however, many experts posit that déjà vu happens when the areas of the brain responsible for sensing familiarity (the medial temporal lobe) relay signals too rapidly, leading to the feeling that we’ve been in a situation before. With that signal, another area of the brain verifies that feeling of familiarity against your memory. When it doesn’t find a matching memory, it leads to déjà vu, in which we feel as if we’ve been in the situation, but cognitively, we know we haven’t.
Some research points to the role of neurotransmitters like dopamine in déjà vu. Studies have shown that increased dopamine activity, particularly in the temporal lobes (involved in memory and recognition), can trigger déjà vu experiences. Déjà vu may be more likely to occur when you're stressed, tired, or anxious, as these conditions can affect the brain's ability to process information accurately. While déjà vu is generally considered harmless, frequent occurrences may be associated with certain neurological conditions, such as temporal lobe epilepsy. During seizures, patients may report intense feelings of déjà vu just before or during the episode.
Is déjà vu good or bad?
Overall, déjà vu is a common experience and isn’t considered a sign of an underlying psychological or neurological condition. Some scientists studying déjà vu say that when it happens occasionally, it’s a good thing because it’s a sign that your memory system is working to “check” itself. When something seems familiar, but we know we’ve never experienced it before, the mechanisms that form memory work together as they should. If they weren’t, we’d likely have problems determining what memories are real.
However, there are rare cases in which focal seizures affect the temporal lobe (the brain region responsible for storing memories), causing episodes of deja vu. Older research reveals stress and fatigue as common causalities for déjà vu, and recent research also suggests a “link between high levels of anxiety and increased frequency and intensity of déjà vu.”
How do you trigger déjà vu?
Déjà vu arises when we encounter something that seems familiar but we’ve never experienced it before. While it might be possible, déjà vu isn’t usually something we can willfully “trigger” because it’s a spontaneous and largely unconscious experience. It is challenging to recreate in the laboratory, although past studies have shown that hypnosis and virtual reality (VR) technology might be effective ways to induce episodes of déjà vu. The possible link between dopamine and elevated rates of déjà vu suggests that using dopaminergic drugs may result in more frequent experiences of deja vu.
A few other factors might inadvertently create experiences of déjà vu. One of the most obvious is being in a place that resembles a previous experience or looks familiar, even though it’s new to you. This might happen when traveling to a place that has similarities to other locations you’ve visited.
Repeated exposure to similar situations, people, or routines could increase the chances of déjà vu. For example, hearing a specific sound or seeing a particular type of scenery that reminds you of something similar might evoke the feeling. Experiencing déjà vu while watching a movie or reading a book is common, especially if the plot or imagery reminds you of something from your life or another story you’ve encountered. This might create the illusion that you’ve lived through the scenario. When you're daydreaming or lost in thought, your brain might mix elements of past memories with your present environment. This overlap between imagined and real experiences might cause a sense of déjà vu.
Why does déjà rêvé happen?
Déjà rêvé, meaning “already dreamed” in French, is the sensation that you’ve experienced something in a dream before, as opposed to déjà vu, which involves the sense that something has been lived before. However, researchers have identified a few potential reasons why it may happen:
Research suggests that déjà rêvé is likely caused by a miscommunication between the brain’s left hemisphere, where dreams are stored and interpreted, and the right hemisphere, which contains the content of our dreams. This miscommunication results in the feeling that you’ve already dreamt about something when it happens in your waking life.
Some experts posit that deja reve might occur when the areas of the brain associated with processing waking thoughts, memories, and feelings “overlap” with those associated with dream and dream interpretation. The blurred line between what you dreamed and what you actually experienced creates the illusion that you dreamed of the current situation before it happened.
Dreams, especially vivid or emotionally charged ones, may create false memories in the brain. If you later encounter a similar situation or event, the brain might misinterpret it as having been experienced in the past when, in reality, it was part of a dream. This can lead to the sensation that what you're experiencing in real life was already encountered in a dream.
Dreams often reflect the subconscious mind’s processing of emotions, desires, and concerns. If you dream about events that resonate with real-life situations (such as common anxieties or desires), and those situations later unfold in real life, the similarity between the dream and real-life experience can lead to déjà rêvé. Your mind may link the emotional or thematic content of the dream to the present experience.
Some people report that they feel like their dreams predicted real-life events, a phenomenon related to precognitive dreaming. This may be an illusion created by memory biases or coincidence. Dreams are often forgotten quickly, so when a real-life situation matches something from a dream, it may feel like the dream "foretold" the event, even though the connection is often vague or coincidental.
Some people report that they feel like their dreams predicted real-life events, a phenomenon related to **precognitive dreaming**. This may be an illusion created by memory biases or coincidence. Dreams are often forgotten quickly, so when a real-life situation matches something from a dream, it may feel like the dream "foretold" the event, even though the connection is often vague or coincidental.
Dreams are often fragmented and quickly forgotten after waking up. Sometimes, a small fragment of a dream may linger in your memory without being fully conscious of it. When a similar situation arises, your brain might connect that dream fragment to your current experience, creating the feeling that you dreamed about the event before it happened.
What is déjà vu trying to tell you?
Some people believe that déjà vu is associated with precognition, past lives, or that you experience it because your unconscious is trying to communicate something of meaning to your conscious mind. There is no scientific evidence to support these theories, and most experts posit déjà vu occurs because the brain may sometimes “misprocess” memories.
Can déjà vu tell the future?
While déjà vu can result in feelings of familiarity in situations we haven’t yet experienced, researchers don’t believe it tells the future.
Is déjà vu a warning?
Déjà vu is common in many people, and while it’s not typically associated with problems in the brain, there are rare occasions that déjà vu might be a sign of neurological problems. For example, déjà vu can result from focal seizure in the part of the brain that stores memories. It may also result from chronic stress, fatigue, or anxiety.
Is déjà vu lucky?
Although some people assign spiritual meaning to it, there is no proof that déjà vu is an indicator of luck or helpful premonitions.
How long can déjà vu last?
Déjà vu experiences typically only last for several seconds. While déjà usually only occurs occasionally, some people experience more frequent episodes up to a few times a week. For example, there have been case studies where individuals with psychological conditions like depersonalization-derealization experience chronic, persistent déjà vu. Research suggests that, for some people, frequent déjà vu may be caused by substance use, migraine, or anxiety. People with temporal lobe epilepsy may also experience déjà vu more frequently than others.
How rare is déjà vu?
Scientists believe that as much as 97% of the population have had déjà vu at least once, and up to 67% experience it regularly. It usually happens most often in individuals between 15-25 years, but episodes of déjà vu tend to decrease with age.
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