People only just realising most commonly thought theory about periods is actually a lie

There are plenty of things we've heard growing up throughout the years that we've come to think of as absolute fact.

From carrots giving you night vision and waiting an hour after eating before going swimming all the way through to catching a cold if you go out with wet hair - there are some old wives tales we simply cannot shake from our minds.

And one of the arguably most famous ones has left people absolutely 'heartbroken' after only just realising an extremely common theory about periods is actually a lie.

Do periods actually sync up? (Boy_Anupong / Getty Images)

It seems quite a few women and people who menstruate - myself included - were under the impression that our periods all sync up if we spend enough time in close proximity together, a concept known scientifically as 'menstrual synchrony'.

However, this is apparently no more than a myth - despite the fact that many swear the timings are far too much of a coincidence.

"It's a popular belief," says Alexandra Alvergne, associate professor in biocultural anthropology at the University of Oxford.

"As humans we always like exciting stories. We want to explain what we observe by something that is meaningful. And the idea that what we observe is due to chance or randomness is just not as interesting."

Many couldn't quite wrap their head around the bombshell revelation upon hearing the news and rushed to social media to share their shock.

The theory known as 'menstrual synchrony' was first coined by researcher Martha McClintock in the 1970s. (Xavier Lorenzo / Getty Images)

One X user penned: "I am devastated to discover that your period syncing with another woman you spend a lot of time with is just a MYTH."

They continued: "There’s no scientific backing for why it could happen and apparently it only happens by chance ???? You’re telling me my soul isn’t bonded with my sisters ????"

A second chimed in: "Menstrual cycle’s syncing up is unfortunately a myth and I feel it’s the most heartbreaking lie ever."

"I don’t know why they really tryna make me believe that cycle syncing is a myth," added a final X user. "They know something that we don’t."

People were 'heartbroken' after discovering the truth behind the period-syncing myth. (toncd32 / Getty Images)

On the subject of periods, free bleeding, AKA the act of freely menstruating without the use of a tampon, sanitary pad, menstrual cup or anything else designed to soak up your flow, is ramping up in popularity among women and people who menstruate, and the reasons are very interesting.

Despite it being the choice of the person in question, free bleeding still finds itself at the centre of debate.

While some people opt to ditch the tampons and other sanitary products for reasons such as preference, comfort or health - others partake in free bleeding as part of a larger movement.

While it isn't a new phenomenon, social media suggests it is becoming a trend among Gen Z as they try it out for the first time or openly embrace it.