Why Do We Experience Deja Vu?

Have you ever entered a room for the first time, and got a strange feeling that you had already been there? That unpleasant familiarity is what we call deja vu - a French term that means "already seen." It can strike anywhere- in an unfamiliar town, in dialogue, or watching a movie- and have us wondering if something deeper is going on inside our heads. Though it might seem mystical, deja vu is actually a curious anomaly of how the brain remembers.

Researchers believe that deja vu happens when the brain's process to generate memories gets temporarily interrupted. When we experience something new, a memory center in the brain called the hippocampus informs the brain if that moment feels familiar or not; however, sometimes the brain confuses us and gives us the message that the experience is familiar, even if we subjectively know that it is a new experience. It's as if our long-term memory overlaps with our short-term memory at that moment causing us to feel as though we have relived that moment before.

Interestingly, deja vu occurs more frequently in people who are younger, especially those who are experiencing additional pressure such as stress, fatigue, or simply trying to process too much information. It might be the brain’s way of fine tuning the memory network by trying to distinguish between memories of what is known, and what is new. Some scientists speculate that this is revealing a memory system that is working well rather than demonstrating a glitch. This is because in order to feel something is familiar, the neural networks are already generating minute connections between present experience and past experiences. 

While deja vu may prove mildly unsettling, it certainly reveals how perplexing and mysterious the human mind can be. Our minds are always trying to put moments, memories, and feelings together to make meaning of the world, and those quite together in sometimes unexpected temporal combinations. The next time that odd zap of familiarity occurs, sit back and take a deep breath. Your mind may just be processing time ahead of schedule for one brief second.