Why is it believed that menstrual cycles synchronize among women?

Has it ever happened to you that yourrules fall exactly at the same time that your roommate, friend, sister, or cousin? And you said to yourself, "this is crazy, we have our rules at the same time"You are far from being the only one who thought of living amenstrual connection form. 🩸

Menstrual health has long been ignored by science. This has given rise to many myths, such as the one about the "rules synchronization".

But science doesn't quite agree. So: fact or fiction?

Rule synchronization: definition

The menstrual synchronization, it’s the idea that women who live together or spend a lot of time with each otherhad their periods at the same time A kind of invisible, almost magical hormonal balance. ✨

But let's be concrete: aThe menstrual cycle lasts on average 28 days, and the period lasts between 3 and 7 days. This means that approximately 25% of the time, a menstruating person is on their period . In other words, the The probability that two people have their period at the same time is very high !

Here is a simple example:
If you live withtwo other women, there is about a quarter chance that you have your period at the same time, at any given moment. 

So no, you are not necessarily "connected by blood," it might just be a beautiful coincidence. 

Which brings us to the question: Where does this very widespread idea of menstrual synchronization come from? ? 🧐

The McClintock Myth: Pheromones and 1970s Science

The idea of the synchronization of rules between women does not come out of nowhere. It comes from a study that became famous in the 1970s, published by the psychologist Martha McClintock.
She had noticed that the female students living in a dormitory noticed their menstrual cycles becoming synchronized over the months.

According to her, this phenomenon could be explained by the action of pheromones (chemical molecule produced by the body, which causes a specific behavior in another member).

But thisstudy is far from flawless. Indeed, it focused on a small group of 135 women, all from the same background, the data was collected manually, without modern computer tools, and the notion of "synchronization" was not clearly defined: from how many days of difference do we consider two cycles to be "aligned"?
And above all, the statistical methods used at the time would not withstand current scientific standards. 😕

Despite these flaws, the study had a significant impact. It has feeds the collective imagination: the idea that women "line up"naturally between them has become a strong symbol of connection, embraced by the media, pop culture, and the collective imagination, everyday conversations!

But does this idea correspond to today's scientific research?
Spoiler: not really. Let's explore that now!

Synchronization of rules and science

SinceMcClintock's study , scientific research has continued to multiply to verify whether the menstrual synchronization exists really. 

And the conclusion is clear:no solid evidence could confirm this phenomenon!

Several studies have attempted toreproduce McClintock's results, but using more reliable methods and larger samples.

Here are some examples:

• In 2006,astudy involving 186 women living together in a university residence found no evidence of synchronization. The researchers have observed that the cycles remained independent from each other, even after several months of living together.

• In 2017, onemuch more ambitious research was conducted in collaboration between the menstrual tracking app Clue and the University of Oxford. Tens of thousands of cycles were analyzed.
  Result: not only was there nono alignment between the women who interactnt, but their cycles even tended to change over time.

To conclude, thescientific datacurrent therefore do not allowno validation of the existence of menstrual synchronization.The myth persists, but the evidence remains absent. 

Why do we get the impression that it is true?

In reality, with somemenstrual cycles which last on average 28 days (but can range from 21 to 35 days depending on the woman), the overlaps are inevitable. By simple probability, it is perfectly normal for two people to have their periods at the same time from time to time, without the need to mention a mysterious connection. 🤗

Yet, despite all this, The idea of rule synchronization remains deeply ingrained in minds. Why does it persist? This is where psychology and culture come into play!

Why do we keep believing in it? 

It must be admitted: we want to believe.

Believe that our periods synchronize with our friend or our sister, it is believe in a deep connection . But this impression can be explained by several things: 

The confirmation bias

The confirmation bias , it's when we do more attention to things that confirm what we already think, and we forget the rest. Confirmation bias is when we mainly see what confirms what we already think and forget the rest.

For example:Do you get your period at the same time as your friend? You say to yourself, "That's crazy, we're synchronized!" but the next month, it's no longer the case? You don't even notice.

Result:We keep in mind the times when the periods coincide, and we forget all the others. Little by little, it gives the impression that the synchronization is real, when it might just be a coincidence. 😊

Symbolic sisterhood

Believe that our bodies connect , it is sometimes believing in a collective strength,a kind of natural sisterhood !

In a world where the rules have long been hidden, taboo, or scorned, the idea of being "in sync" with other women is comforting. It gives a feeling of unity, of belonging and solidarity. It’s a way of saying: “I am not alone, we are going through this together.”

Even if it is notnot a biological reality, this belief cancreate connections and strengthen relationships.💪

Cultural Influence

Themenstrual synchronization is a very common idea in pop culture.

She can be seen in series like Sex and the City, Big Bang Theory, The Office, or in movies where women laugh or cry together because they have their periods at the same time.
The advertisements for pads or tampons also showgirl groups who experience their periods as a shared moment.

By seeing these images repeatedly, we end up believing them. Themenstrual synchronization becomes a cultural truth, even if they are not always scientific. 🧐

Rather than a hormonal influence, several researchers talk about everyday synchronization :

1. Shared life: When living together, we often share the same rhythms: we eat at the same time, go to bed at the same time, and share the same stress. These factors can affect our bodies in similar ways.
   
2. Emotional connection: Being close to someone means being attentive. When a friend has a stomach ache or is tired, you notice it and may feel like you are experiencing the same thing as them.
   
3. Selective attention: We mainly remember the moments when we are "in sync," and we forget the others. It's our memory that sorts it out. ✅
   
   
4. Need for meaning: Believing in synchronization also means giving meaning to our rules. It makes the experience less solitary, more collective, more beautiful. We feel connected to one another.

If thesynchronization of rules seduces just as much today, perhaps also because it is part of a long tradition of stories and beliefs surrounding the menstrual cycle . For long before science got involved, the rules already had a symbolic dimension, almost sacred.

History: When Menstruation Was Sacred

Long before scientific debates, menstruation already held an important place in many cultures. Far from being merely biological, the rules were surrounded by rituals, beliefs, and sometimes even mystery!✨

Red tents: a space apart

In some traditional societies, such as among the Indigenous peoples of North America or in certain African and Asian cultures, the women who were menstruating withdrew to specific places : the "red tents" or "menstrual huts".

It was a special moment, away from the daily tasks. There,women rested, meditated, or chatted with each other. This withdrawal could be seen as isolation, but also as a reconnection time to oneself, of feminine wisdom or even spiritual power.

The lunar cycle: a natural rhythm

The The moon takes about 28 days to orbit the Earth, just like the average menstrual cycle. This link has often been interpreted as evidence that women are connected to nature and its rhythms.

Some beliefs saw women as "moody," associated with cyclical energies, fertility, or intuition. It was said that bleeding during the full moon or new moon revealed a certain type of inner energy (creative, fertile, or intuitive). 😊

A recurring idea in popular culture

Today still, theseancient visions influence our imagination. In advertising, literature, or series, periods are often described as a moment of power or connection among women. Women are shown dancing together, laughing, or support each other during their periods , as a nod to this supposed harmony between female bodies. 🌸

And if finally, themyth of period synchronization was only a modernized legacy of those ancient stories? A way, even today, to make some rules a space of connection, meaning, and sisterhood.

So, Do periods really synchronize? ? From a scientific point of view, the answer is no.
The studies found no solid evidence. What is perceived as synchronization is often due to chance or selective memory.

But if this idea persists, it is because it resonates with much more than just a question of biology. It speaks of link , from sisterhood , desire to feelconnected among women . 🤗

Believe in period synchronization, it is not necessarily believing in an exact science, it is believing in a collective experience , human, intimate. Even if it is not proven, it has real value. 🩷

And you, have you ever had the feeling that your periods synchronized with those of your close ones ?