If you've ever experienced déjà vu you know how confusing it is. It feels so familiar, yet there's no way that something could have happened already. Unless you are a time traveler, it makes no sense to experience things twice, especially when it always seems to be the most mundane situations.
How does it really happen? It can't possibly be witchcraft (or can it) so there has to be a reason right? Well, scientists have been trying to figure it out for years but it's not easy to do.
Déjà vu is experienced by a lot of people, approximately 70% of the population. It is most likely to happen to people who are between 15 and 25 years old. It's hard to test for déjà vu because you never really know how to spark it, causing the research to be limited, but there are some experimental studies that have been done. While it has been hard to come up with valid theories, they have a few that are promising.