Do Periods Really Sync Up?

Do Periods Really Sync Up?

We’ve all heard it, or at least some version of it - if you spend a lot of time with people with periods, you are all going to end up on the same cycle. Maybe it’s all of your hormones influencing one another and trying to sync up, or maybe there is an alpha who everyone else’s periods sync up to. Either way, you can count on there being one particular week of the month where you make sure to have extra chocolate around and lots of spare tampons. But how based in science is this fun and popular myth?

Turns out, this rumor is actually based in science. According to the Cleveland Clinic, this thought stems from a study conducted in 1971 and published in Nature. This study suggested that “pheremones or other factors can influence and shift periods for women who live together,” producing the menstrual synchronization myth called the McClintock Effect. There is a lot of supporting evidence to suggest pheremones play a key role in many different human behaviors and activities, but is this one of them?

Ultimately, there is no supporting research that other people’s cycles affect the menstrual cycles of others. In a study conducted in 2006 and published by the National Library of Medicine, data was collected from 186 women living in dorms together for over a year. In their research, they found that any synchrony to their cycles was by chance and that there was no scientifically based evidence that their cycles were being affected by one another’s cycles.

Now, living with other people can certainly produce changes in lifestyle that can affect your periods. In fact, there are many life experiences and factors that can change your period. Your diet, activity level, stress level, and chronic illness are all factors that can and likely will affect your period. And these can be caused directly or indirectly by living with other people. 

So although a fascinating concept, it seems this one is just a myth. But hey, who wouldn’t want to be even more connected to one another? 


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