Ever noticed how you and your best friend seem to get your periods around the same time every month?
You joke about being “cycle sisters” syncing in moods, cravings, and cramps.
But is menstrual synchrony really a thing, or just one of those comforting coincidences we like to believe in?
Let’s find out.
Where the Idea Began
The concept of menstrual synchrony goes way back.
In 1971, psychologist Martha McClintock published a study suggesting that women living together (like college roommates) tended to have their cycles align over time, thanks to pheromones or chemical signals influencing hormonal rhythms.
The study sparked curiosity and decades of conversation and even gave rise to the term “McClintock Effect.”
What Science Says Now
Fast forward to modern research and the results aren’t as romantic.
Multiple studies have tried to replicate McClintock’s findings, but most couldn’t confirm a consistent pattern.
Here’s what science suggests:
- Cycle lengths vary naturally. Your period might be 26 days, your friend’s 31, which means overlap can happen occasionally just by chance. Try our Cycle Sync Combo support every stage of your flow, from light to heavy, no matter your cycle length.
- Hormones work independently. There’s no solid biological mechanism proving pheromones can truly sync menstrual cycles.
- Confirmation bias plays a role. We tend to notice when our periods align, but ignore when they don’t.
So while the “Cycle Sisters” theory sounds heartwarming, it’s more myth than medical fact.
But Here’s the Beautiful Part
Even if our bodies don’t literally sync, our experiences often do.
We support each other through cramps, moods, and mid-day chocolate cravings.
We encourage each other to try new products, rest when needed, and celebrate being in tune with our cycles — in our own ways.
That’s what true Cycle Sisterhood is about — empathy, not exact timing.
So next time you’re sharing those “same day” PMS memes, gift your sister a pair of Nushu Period Wonderwear made with ultra-soft bamboo fabric and 4-layer leak-lock protection that keeps you both comfortable through every mood and moment.
At Nushu, We Believe…
Periods don’t have to be isolating.
They’re powerful reminders of connection to your body, to your rhythm, and to the women around you.
From our Seamless Hip Hugger, giving you and your partner-in-flow an invisible fit under any outfit, to the Teen Hipster designed for the younger sister just beginning her period journey — there’s a Nushu for every phase of womanhood.
So whether you bleed together or not, celebrate your Cycle Sisters — because every shared laugh, rant, and “I feel you” moment counts.
Join the Flow Co. Sisterhood 💜
Every Nushu order helps spread awareness and access to sustainable period care.
Invite your bestie to make the switch too — through our Refer-a-Friend Program where both of you earn ₹150 off your next order.
Because real sisterhood means helping each other flow better — together.
