Here's When You Should Worry About Having Deja Vu

According to a 2018 study published in Psychiatria Danubina, déjà vu is a common phenomenon experienced by an estimated 97% of people at least once. It is a transitory sensation of having already lived in an identical situation at some point in the past. The term "déjà vu" translates in French to "already seen."

The feeling of déjà vu is when the brain creates an illusion of familiarity with a situation that the person has not experienced before. This feeling occurs because two parts of the brain responsible for memory and familiarity are not communicating effectively, leading to confusion. Per the Cleveland Clinic, this false sense of familiarity can be unsettling because the situation should not feel familiar.

While occasional déjà vu experiences are normal and not a cause for concern, frequent occurrences can be a symptom of a health issue. It can be a symptom of anxiety or a more serious medical condition, such as epilepsy or cardiovascular diseases.

Some brain conditions have been linked to having déjà vu experiences. Temporal lobe epilepsy can cause unusual electrical activity in the brain that leads to déjà vu before a seizure (per the Mayo Clinic). People with various psychiatric disorders may also have déjà vu, according to a 2004 report in the Journal of Neurology, Neurosurgery, and Psychiatry. A 2021 study published in the journal Memory found that individuals with anxiety are more likely to experience déjà vu than others, and their experiences may cause them distress. 

Déjà vu can be a sign of some types of dementia and migraine, as stated by the Cleveland Clinic. People with frontotemporal dementia, for instance, often experience persistent déjà vu and try to rationalize it. And while rare, some people may experience déjà vu as part of the aura symptom before a migraine attack (per Practical Neurology). The aura is a distinct phase that comes before the headache. 

In addition to neurological conditions, a report published in 2023 in Current Problems in Cardiology suggests a connection between frequent déjà vu experiences and cardiovascular diseases. Reduced blood flow to the brain, a common aspect of cardiovascular issues, could contribute to déjà vu-like sensations. If you've been experiencing frequent déjà vu accompanied by symptoms that worry you, be sure to get in touch with your primary care provider.

To understand when déjà vu is a typical experience, knowing a few things is helpful. For instance, if it happens occasionally and isn't always happening, it is considered normal. According to a study published in 2012 in The Journal of Mind and Behavior, déjà vu is often attributed to a temporary misalignment in the brain's processing of incoming information. The brain's memory and perception systems work intricately together, and déjà vu may occur when there is a momentary glitch in this coordination. The brain may mistakenly interpret a present experience as a memory, creating the sensation that the current moment is a replay of a past event.

Déjà vu is a phenomenon many experience only a few times. It is often triggered by stress, fatigue, or sleep deprivation, temporarily affecting the brain's processing speed (per Penn Medicine). This can lead to a momentary misalignment in memory and perception. Research suggests that déjà vu is more common in younger individuals and tends to decrease with age. As the brain matures, these experiences may become less frequent.

Déjà vu is also linked to the brain's remarkable ability to recognize patterns. When faced with a situation resembling past experiences, the brain may momentarily confuse the present moment with a previously encountered scenario, creating the sensation of familiarity.  Normal déjà vu is brief and does not persist for an extended period or become intensely overwhelming.