Do you believe that your period syncs up with your close friends, roommates, or family members? If so, you’re not alone. Many women swear by this phenomenon, and some even find it comforting or empowering to feel connected to other women who menstruate. But is there any scientific basis for this belief, or is it just a popular myth?
Period syncing, also known as menstrual synchrony or the McClintock effect, is the idea that women who live together or spend a lot of time together begin menstruating on the same day every month. It’s based on the theory that women’s pheromones influence each other’s menstrual cycles, but there is no scientific evidence to support this claim.
The origin of this theory can be traced back to a 1971 study by Martha McClintock, who conducted a survey of 135 college women living in a dorm together and found that their periods seemed to align over time. This study sparked a lot of interest and controversy, and was dubbed “the McClintock effect” by the media.
However, since then, many researchers have challenged and debunked this claim, using more rigorous methods and larger data sets. For example, in 2006, a study of 186 women living in groups in a dorm in China concluded that “women do not sync their menstrual cycles” and that any apparent synchrony was due to mathematical coincidence.
More recently, in 2017, a large study conducted by Oxford University and the period tracking app company Clue analyzed data from over 1,500 people and found that it’s unlikely that women can disrupt each other’s menstrual cycles by being in close proximity to one another. The researchers also noted that factors such as stress, diet, exercise, and birth control can affect the length and regularity of menstrual cycles, making them more variable and unpredictable.
So why do so many women still believe in period syncing? One possible explanation is confirmation bias, which is the tendency to look for and remember information that confirms our existing beliefs and ignore information that contradicts them. For example, if you notice that your period starts on the same day as your friend’s once or twice, you might think that it’s a sign of syncing, but if you overlook the times when your periods are out of sync, you might not realize how random it actually is.
Another possible explanation is the emotional connection that some women feel with other women who menstruate. As Dr. Brytanie Marshall, an obstetrician and gynecologist at Geisinger, says: “Feeling emotionally connected to other women who are going through the same thing you are can certainly be comforting.” Even if period syncing is a myth, maybe the feeling of solidarity and support is what matters more.
Period syncing is one of those myths that won’t go away easily, despite the lack of scientific evidence. Whether you believe in it or not, it’s important to remember that every woman’s menstrual cycle is unique and influenced by many factors. The best way to keep track of your cycle and health is to use a reliable period tracking app or calendar, and consult your doctor if you have any concerns or questions.
– Period Syncing: Fact or Myth? – Dr. Brahmanand Nayak, April 30, 2023
– Does Your Period Sync Up With Close Friends? – Cleveland Clinic, January 21, 2022
– Period Syncing: Real Phenomenon or Popular Myth? – Healthline, January 21, 2022