Have you ever gone to a place and suddenly felt like it wasn’t the first time there? Or found yourself in a situation and wondered if you experienced it in a dream or if it actually happened in the past?

The sensation that you’ve already experienced something, even when you know you never have is called ‘déjà vu’, a French vocabulary for ‘already seen’. Experts say it can peak in young adulthood, but gradually go away with age.

According to Dr Cindi Cassady, a senior clinical psychologist at Caraes Ndera Neuropsychiatric hospital/ Icyizere Centre, the moment of déjà vu is fleeting, lasting just a second.

Unfortunately, no single agreed-upon model explains exactly what happens in the brain during déjà vu.

"Déjà vu occurs when areas of the brain such as the temporal lobe feed the mind’s frontal regions signals that an experience is repeating itself. Then, the brain’s frontal decision-making areas effectively check to see whether or not this signal is consistent with what is possible. It will ask ‘have I been here before? If you have actually been in that place before, you may try harder to retrieve more memories. If not, a déjà vu realisation can occur,” she explains.

Alexis Manzi says at first when he experienced this feeling, he thought he was going crazy.  "My first time having this sensation, I thought something was wrong because I would think I have been to this place before and try hard to remember but end up having no memory of the place. They started as normal sensations but they started becoming frequent,” he says.

 When this happened, Manzi decided to visit a doctor for reassurance, although he was hesitant, worrying that he could be having serious issues with his brain "At some point, I felt I had a problem, so I went to the doctor. But she explained to me that they were common feelings to have though mine were becoming frequent because of too much exhaustion and stress from work and school,” Manzi says.

He was advised to reduce the stress and rest more, which reduced the frequency.

The sensation is said to mostly happen to people who travel often and have college or advanced degrees.

"Being busy, tired, and stressed out tends to bring on more feelings of déjà vu. People who are exhausted or stressed tend to experience déjà vu more. This is probably because fatigue and stress are connected with what likely causes most cases of déjà vu: memory,” Cassady explains.

Memory is stored in a part of the brain called the temporal lobe. Long-term memories, events, and facts are all pushed right to that area of the brain. Specific parts of the temporal lobe also play a role in recognising something as familiar.

According to Dr Cassady, in rare cases déjà vu can be a sign of a neurological disorder. Individuals with epilepsy often have focal seizures that occur in one area of the brain, sometimes in the temporal lobe where we store memories.

"These are called temporal lobe seizures. Seizures are bursts of uncontrolled electrical activity that cause nerve cells in your brain to misfire. The shortness of focal seizures and the fact that people typically remain awake when they happen makes it hard to recognise what's happening. People may mistake a person having a focal seizure as daydreaming or staring off into the distance,” Cassady explains.

Temporal lobe seizures impact your ability to interact with other people. Most of them last anywhere from 30 seconds to minutes, you may lose awareness of your surroundings. Others may observe you smacking your lips or constantly chewing and swallowing during the seizure.

"Once they end, you may find yourself feeling confused. It may be difficult for you to speak or remember what happened while having the seizure. A temporal lobe seizure can become a more serious tonic-clonic (or grand mal) seizure that causes convulsions and makes you lose consciousness,”Cassady explains.

Signs that you may be having a temporal lobe seizure versus a regular déjà vu experience 

Sudden, unexplained feelings, like joy or anger

Problems controlling your muscles

Twitching in your muscles

Having sensations that involve vision, taste, smell, hearing, and touch

Feeling as though you are about to have a seizure

In any case, one would start having symptoms of temporal lobe seizures or neurological issues they should go to a neurologist for an evaluation.