If you’ve known someone long enough and have crossed that ‘TMI’ barrier, you’ll likely hear it when they’re cramping, bleeding, or having that premenstrual bloat. As time goes on, you start to realize that the two of you are starting your periods suspiciously close to one another — for whatever reason, your periods are in sync. Or… are they? Do periods really sync?
For centuries, there’s been a popular belief that when people who menstruate live together or spend a lot of time with each other, their periods eventually sync. This phenomenon, known as “menstrual synchrony” or the “McClintock effect,” has captivated the curiosity of both scientists and laypeople alike. But how much of this belief is grounded in science, and how much is it a myth? Let’s dive deep into the mysteries and science behind the idea of periods syncing up.
The Origin of the ‘Synced Periods’ Theory
The theory of menstrual synchrony was first proposed by Martha McClintock, a researcher from Harvard University, in 1971. McClintock’s study, published in the journal “Nature,” observed 135 female college students living in a dormitory. She reported that the onset of their menstrual periods became more synchronized over time. This suggested that some form of social or biological interaction played a factor.
This study sparked widespread interest and led to the idea that individuals could influence each other’s period cycles through pheromones chemical signals, which can in turn affect the behavior or physiology of others of the same species. The media quickly picked up on the notion, and it soon became a part of popular culture.
Pheromones: A Biological Basis?
Pheromones are well-documented in the animal kingdom, where they play crucial roles in communication, mating, and social behaviors. From there came the concept of human pheromones being responsible for menstrual synchrony. This theory suggests that people might subconsciously emit and detect pheromones that could influence their hormonal cycles.
Several studies have attempted to identify specific pheromones that could be responsible for menstrual synchrony. However, the evidence remains inconclusive. Some studies have found hints of synchrony, while others have failed to replicate McClintock’s findings. One notable study, conducted by Stern and McClintock in 1998, suggested that compounds extracted from women’s armpits could affect the timing of other women’s menstrual cycles. Despite these findings, the scientific community remains divided on whether pheromones have a significant impact on menstrual cycles. At the moment, the current consensus on “do periods sync” is still “probably not.”
The Role of Random Chance
One of the main criticisms of the menstrual synchrony theory is that the observed synchrony could be due to random chance rather than any biological mechanism. Menstrual cycles vary in length among different individuals, typically ranging from 21 to 35 days. Given this variability, cycles might align occasionally just by coincidence.
Research has showed that in any group of people with varying cycle lengths, some degree of synchrony is likely to occur by chance. This means that anecdotal reports of menstrual synchrony might be explained by random alignment rather than pheromonal influence.
Social and Psychological Factors Affecting Women Periods Syncing
It’s also worth considering the social and psychological factors that might contribute to the perception of menstrual synchrony. When groups of people live together or spend a lot of time with each other, they often share experiences and discuss their menstrual cycles. This can create a heightened awareness of each other’s cycles and lead to the belief that they are syncing up. Additionally, the placebo effect where individuals experience changes simply because they expect them might play a role. If you believe that your cycles will sync up with your close companions’, you might perceive patterns that aren’t there.
Similarly, if you’re living with a partner, friend, or sibling, you are likely eating much of the same foods and even potentially engaging in some of the same daily activities. These outside factors can have an influence on your period and theirs, which could potentially lead to subtle changes in when those menstrual cycles occur.
Recent Research Conducted on Periods Sync
In recent years, more studies have been conducted to investigate menstrual synchrony. Many of these studies have used larger sample sizes and more precise statistical methods than earlier research. The results have been mixed, with some studies finding no evidence of synchrony. The idea that periods can sync up is, ultimately, a myth.
The story of menstrual synchrony is a result of the complexity of human biology. As our understanding of hormones, pheromones, and social behaviors continues to evolve, new insights may emerge that shed light on this phenomenon. Until then, the idea of periods syncing up remains an intriguing blend of science and speculation.