What Is Déjà Vu?

Déjà vu, French for 'already seen,' is the eerie feeling that you've experienced the current moment before, even though you know you haven't. About 60-70% of people have experienced this phenomenon. Scientists believe déjà vu occurs when there's a brief miscommunication in the brain, particularly between the areas responsible for memory recognition and memory formation. One theory suggests it happens when your brain processes current sensory information through memory circuits before conscious awareness, creating the illusion of a memory. Another theory proposes it's caused by a tiny time lag in processing information from your eyes to different parts of your brain. Déjà vu episodes typically last just a few seconds and are more common when you're tired or stressed. While it can feel strange, déjà vu is completely normal and not a sign of any medical problem. Interestingly, the opposite phenomenon exists too: jamais vu ('never seen'), where familiar things suddenly seem completely new.