Periods Don’t Sync Up, No Matter How Much Time People Spend With Each Other


Dec 3, 2019


The myth that people with periods, by sheer virtue of being around each other for a certain period of time, can summon nature’s mysterious powers to coordinate when their uteruses bleed out once a month, has invaded the collective psyche of our society. But no matter how many movies and television shows celebrating female friendship perpetuate the period-syncing phenomenon — looking at you Jane the Virgin, New Girl, Sex And The City — it’s still not true. No conclusive, reliable scientific evidence proves periods sync up when people spend time with each other. Instead, plenty of societal evidence explains why we are so damn set on believing the myth.

Many studies, including this 1971 study out of Wellesley University published in Nature, have attempted to establish “menstrual synchrony,” or the phenomenon of synced periods when menstruating people spend time around each other. But subsequent researchers, such as Beverly Strassmann, an anthropology professor at the University of Michigan, have largely debunked the myth of menstrual synchrony, and have alleged the findings of past researchers to have been borne more out of chance than rigorous scientific study. In an interview with The Atlantic, Strassmann explained that for an average menstrual cycle of 28 days, with menstruation lasting for an average of five days, the probability that two or more people will have some parts of their periods overlap is common logic.

Despite research like Strassmann’s permeating the news cycles often, pop culture and societal psyche remain firmly rooted in the belief that periods sync up. A gender studies researcher at Arizona State University, Breanne Fahs, in a 2016 study asked 20 women how they felt about menstrual synchrony. She found 90% of women believed in the phenomenon. Fahs identified common themes as to women’s understanding of period-syncing myth: “(1) connection to and hierarchy among other women; (2) menstrual synchrony as ‘magical’ or ‘mysterious’; (3) menstrual synchrony as biological and animal-like; (4) managing and overcoming negative experiences with menstruation.”

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Fahs’ main takeaway from her research, as stated to The Atlantic, was a need for community among the women she interviewed, especially when they were menstruating. “Women … expressed that menstrual synchrony allowed them to express anger together with other women; anger served as a platform for solidarity as women by allowing them to be more demanding or forceful,” Fahs writes. For one woman, Fahs recounts, there was also a “don’t mess with us” mindset when she believed her period was synced with her friend, which signaled to Fahs that the period-syncing phenomenon was making women comfortable with their pain and anger, as they saw it reflected in another woman in their proximity.

Another factor that immutably fuels said anger and pain is women’s distrust of medical establishments, especially because many medical professionals don’t take women’s pain seriously. Women’s accounts of their experiences with their gynecologists have repeatedly shown their physical pain is considered a part and parcel of having a female body and that ‘suck it up’ is more often than not the advice given to them. In believing women have synced up with one another, women not only share the pain, but also the sense of betrayal and ignorance they are made to feel by those refusing to listen when they talk about their bodies, Fahs concluded.

As science doesn’t support the period-syncing myth, looking at what individuals get out of this misconception might just make the presence of the faulty research out there okay. If having another someone else with whom to discuss the evils of menstruation, with whom to sit and grumble about cramps, and with whom to bond over gaslighting stories gives menstruating people the much-needed respite during periods, may the myth persist — at least until science figures out how to make periods not one of the worst things to happen to female bodies every month.


Written By Rajvi Desai

Rajvi Desai is The Swaddle’s Culture Editor. After graduating from NYU as a Journalism and Politics major, she covered breaking news and politics in New York City, and dabbled in design and entertainment journalism. Back in the homeland, she’s interested in tackling beauty, sports, politics and human rights in her gender-focused writing, while also co-managing The Swaddle Team’s podcast, Respectfully Disagree.


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