The Myth of Synchrony

For as long as women have lived beside each other, they have whispered about their cycles syncing.

Sisters notice it first.
University roommates swear it happens.
Long-term friends laugh about how it “always” aligns eventually.

The idea feels ancient. Almost folkloric. Something passed between women in bathrooms and bedrooms rather than discovered in a laboratory.

And then, in the 1970s, it was studied.

A small paper published in 1971 suggested that women living in close proximity experienced menstrual synchrony. The study was limited. The sample was small. It was also the 1970s, and research into women’s bodies was not exactly the scientific priority of the decade. Since then, larger studies have struggled to replicate the findings consistently. Statistically, the evidence is weak.

Science, at least for now, remains unconvinced.

And yet, a part of me hesitates to dismiss it entirely. Perhaps it is because it was the 1970s. Perhaps it is because research into women has historically been underfunded, understudied, and frequently misunderstood. Or perhaps it is simply because I am choosing to keep a small pocket of hope alive. For cycle syncing. And for mermaids.

But here is what is interesting.

Nearly half a century later, women are not convinced it is false.

The belief persists. Across generations. Across cultures. Across shared apartments and shared lives.

Which suggests that even if the mechanism is unclear, the experience feels real.

Science can measure hormone levels. It can track cycle lengths. It can calculate probability. But science cannot always capture the texture of being a girl at eight years old, packing your overnight bag for your first sleepover and feeling that quiet thrill of belonging. It cannot measure the electricity of whispering in the dark at fourteen about the boy you like, your secrets braided together with your hair. It cannot quantify the way your stomach drops when, at thirty, you sit across from your best friend and tell her you are pregnant, or not pregnant, or heartbroken, or terrified, and she understands before you finish the sentence.

When women live together, they share light exposure, sleep rhythms, stress levels, meals, conversations, and secrets. But they also share formative moments. They share firsts. First bras. First kisses. First griefs. They share breakups on kitchen floors. They share laughter so hard it feels like survival. They share silence that feels safe.

Hormones are sensitive to stress and safety. They respond to environment. And female friendship has always been an environment of profound exchange. Not just biologically, but emotionally. Developmentally. Spiritually.

Historically, romantic love has been positioned as the pinnacle. Familial love as sacred. Marriage as milestone. Motherhood as destiny. Female friendship, in comparison, has often been framed as supportive but secondary. Nice to have, but not central.

And yet.

Across centuries, across continents, the only relationship that has carried a long-standing myth of biological closeness is the one between women.

We do not tell stories about brothers’ hormones aligning. We do not speculate that fathers and sons regulate each other’s internal rhythms. But we do imagine that women, living side by side, might begin to bleed together.

I do not think that is accidental.

Perhaps in times when emotion was not taken seriously, when women’s interior lives were dismissed or reduced, there was a need for a tangible explanation. A solidified one. Something physical. Something undeniable. So maybe the story became that our bodies align. That our uteruses link up. That biology confirms what culture overlooked.

Maybe cycle syncing was never about calendars.

Maybe it was about closeness.

Maybe it was a way of saying: we shape each other.

And perhaps the persistence of this myth tells us something more enduring than data ever could.

So this month, instead of asking whether synchrony is statistically probable, take a quiet minute to observe the women in your life.

Notice the friend who steadies your mood without trying.
The sister whose stress you feel before she names it.
The colleague whose burnout makes your own exhaustion surface.
The woman whose joy lifts something in you without explanation.

Pay attention to how your energy shifts around certain women. Notice how your body softens. Notice how proximity changes you.

You do not have to prove anything. You do not have to land on a scientific conclusion. Just observe.

Your female relationships are doing more than you think they are doing.

Perhaps they always have been.

Love,
Ava