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Can Periods Sync?

Can Periods Sync?

September 18, 2023

For years, the idea that periods can sync among close friends or roommates has been a topic of debate. The phenomenon suggests that menstruators who spend a significant amount of time together are bound to have their menstrual cycles aligned. 

Let’s take a closer look to determine whether or not there is any truth behind it 👀.

The Origin of the Myth

The notion of menstrual syncing gained popularity in the 1970s, thanks in part to a study published by Martha McClintock, a psychologist, in the journal “Nature.” McClintock’s study claimed to find evidence that periods could indeed synchronize among roommates. 

Biological Plausibility

The idea of period syncing raises questions about the biological mechanisms that might be at play. Some theories suggest that pheromones, chemical compounds that can influence behaviors and physiological processes, could be responsible here. It was proposed that menstruators might release pheromones which could subtly impact the periods of those around them. 

Scientific Scrutiny

As much as I want to sync up with my besties, subsequent research has cast doubt on the validity of period syncing. Numerous studies attempting to replicate McClintock’s findings have yielded mixed and inconclusive results. In fact, a comprehensive analysis published in the journal “Psychoneuroendocrinology” in 2006 found no substantial evidence supporting the idea of menstrual synchrony.

You just have to be scientific giphy

Factors at Play

You may be thinking to yourself, “Well, there have been several occasions where I’ve synced up with my roommates and friends!” Been there. But, there are quite a few factors that can contribute to the perception of menstrual syncing even when no actual synchronization is occurring.

  1. Variability in Cycle Lengths: Menstrual cycles naturally vary in length from person to person. With the range of cycle lengths being quite wide, it’s statistically likely that some periods will overlap purely by chance.
  1. Selective Attention: People tend to notice patterns more when they’re looking for them. If two menstruators are aware of each other’s cycles and are actively tracking them, they might start to perceive synchrony even when it’s coincidental.
  2. Small Sample Sizes: Many anecdotal accounts of period syncing involve small groups of menstruators. With only a few individuals involved, the chances of their cycles coinciding increase.

The Takeaway: Myth or Reality?

At this point, the scientific consensus leans heavily toward the idea that menstrual syncing is more myth than reality. While it’s entirely possible for menstruators’ cycles to coincide occasionally due to random chance, there is insufficient evidence to support the idea that a biological mechanism is at play. 

Learn more about ALL things menstruation on our blog, The Periodical!

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claire coder,founder + ceo

claire coder,
founder + ceo

Hi! I’m Claire. I founded Aunt Flow after getting my period in public without the supplies needed.

At 18 years old, I dedicated my life to developing a solution to ensure businesses and schools could sustainably provide quality period products, for free, in bathrooms. Our products are made with organic cotton and we are constantly working to reduce our environmental impact! Since 2021, we've donated over 6 MILLION period products to menstruators in need. I call this people helping people. PERIOD.®