There are pretty much only two reasons periods ever get discussed on prime-time television: first, to draw attention to their lateness, thus introducing a pregnancy story line. And second, to note that two characters’ menstrual cycles have synced, indicating that they’ve been bonding or spending a lot of time together. In an episode of Jane the Virgin that aired earlier this year, for example, Jane and her fiancé, Rafael, briefly compete over which of them has a closer relationship with another character, and Jane boasts to Rafael that “Petra and I are on the same cycle.” Sex and the City and GLOW have employed synced-up periods for a similar purpose, while other shows—Modern Family, The Office, Community, New Girl—have invoked the idea as a punch line.
For a phenomenon that’s highly unlikely to be real, period syncing has enjoyed an impressively long life in the popular imagination. Every now and again, news stories and listicles pop up to inform the public that no, actually, period synchronization as a result of prolonged proximity is not a thing, but the fictional story lines and offhand jokes persist nonetheless.
TV and movies certainly help maintain the popularity of the period-syncing myth. But to some extent it survives because so many people want it to be true. No matter how inaccurate the myth of period syncing may be, the idea that women’s bodies can fall into collective rhythms carries a certain mysterious, otherworldly appeal and, lending the myth more inertia, gives women a way to feel connection, empathy, and collective empowerment with other women.