What causes déjà vu and why does it feel so familiar?

Have you ever been somewhere new and suddenly felt like you’d been there before? That’s déjà vu, and it happens because your brain gets a little confused.

Imagine you're playing with your favorite toy, and you see something that looks just like the toy. Your brain thinks, “Wait… I’ve seen this before!” even though it's not exactly the same toy. That’s kind of what happens with déjà vu, your brain sees or hears something familiar, but not quite the same as before.

Your brain has two parts that help you remember things: one that works quickly and one that takes a little longer to think. Sometimes, the quick part says, “I know this!” before the slower part catches up. That’s why it feels so familiar, like your brain is saying, “Hey, I’ve seen this before, but I’m not sure how!”

It's like when you're eating a sandwich and suddenly feel like you've eaten that same sandwich before, even though it’s not the exact same one. Your brain just had a little mix-up!