Hold onto your hats, ladies, because a popular belief about your period is about to get debunked.

Have you ever noticed your period ends up coming at the same time as the women who live around you? According to common knowledge, this means your menstrual cycles have "synced up." No one knows exactly why this happens - we just chalk it up to the magic of our bodies.

But what if the whole thing was completely false?  

In a study led by period tracking app Clue and the University of Oxford, researchers found that it's "very unlikely that cycle syncing is a real phenomenon."

Based on 360 pairs of women who live together, only 87 pairs ended up having their period around the same time. That's a very small percentage when you consider that 273 pairs had varying cycles.

Marija Vlajic, a data scientist from Clue, said: "Menstrual syncing amongst the sample we had did not exist. We've also done some statistical tests and found that the difference in cycles actually grows. This doesn't mean that pairs go out of sync "“ it means they were never in sync in the first place. It's the nature of two mathematical series that keep repeating: the series will diverge as the numbers grow."

Despite the new findings, a 1999 study states that 80% of women believe in menstrual syncing. If so many women think it's true, surely there's some weight to it?

Vlajic explains: "There will be a time every six months when your periods sync but that doesn't mean the difference is getting smaller. I just think it's information bias; our brains looking for patterns."

So there you have it. Period syncing is a myth. Let us know in the comments section if you agree with the study. Are they missing something?