Why do we experience déjà vu and what causes this strange sensation?

We experience déjà vu when our brain thinks it has already seen something, even though it hasn’t, like seeing a toy and thinking you’ve played with it before.

Imagine your brain is like a robot that takes pictures of everything around you. Sometimes, the robot gets confused and matches a new picture to an old one. That’s déjà vu! It happens when parts of your brain work together in just the right way, or sometimes in a slightly wrong way.

Your brain has two main teams: one that helps you remember, and one that helps you pay attention to things happening right now. When these teams don’t quite agree, it can feel like you’ve seen something before when you haven’t. It’s kind of like when you think your friend is wearing the same shirt as yesterday, but they're actually wearing a different one.

Sometimes, this trick happens because you're tired or thinking about other things at the same time. It’s just your brain trying to make sense of everything around you, and it doesn’t always get it right!