The Science Behind "Syncing Up"

We have all heard it before. “Oh, we are synced up!” or “I am on my period too, we must be synced.” 

Syncing up is the popular belief that menstruators that spend a lot of time together, end up having the same cycle. This idea has mostly been spread and solidified by anecdotes and personal experience. 

Some people believe that there is an ‘alpha female’ who is the one that determines the menstruation cycle of the menstruators around them. Some men, like Winston from New Girl, have gone as far to say that they have experienced syncing up too...but that’s besides the point. 

With all these stories flying around about syncing up, what is true? Can this actually happen? 

This was first scientifically backed with a study done by Martha McClintock which followed 135 college women living in a dorm together. The main thing that was tracked was the monthly bleeding of the women, which were in fact ‘synced up’. 

Since then, there have been various studies that have tried to come to a conclusion about period syncing. 

• In a 2006 Chinese study, it was found that women do not sync their cycles and any period syncing that appeared was mathematical coincidence. 
• In a study done by Oxford University and Clue, the period-tracking app, it was concluded that it is unlikely that women can change each other’s cycles by being close to one another. 
• In a 2017 study, it was found that 44% of participants experienced syncing and period symptoms like migraines were more common with women living together. 

The thing is, we may never be able to prove if people can sync their periods based on proximity. There are a couple reasons why it would be hard to prove.

• Pheromones: these chemical signals are sent to humans around us; they help with attracting others, fertility, and so on. This can be a reason that menstruators potentially signal to one another that it’s time to menstruate. 
• Cycle times: cycles can last for 28-40 days and periods look different for everyone. This means it’s hard to pin down a time that is defined as ‘syncing up.’ Say you live with 3 other menstruators. If you have your period for one week, there is a chance that at least 2 people WILL have their period at the same time in the house. It’s just a matter of catching up with one another: someone has it for a week, another person starts at the tail-end of that week, and so on. 

Regardless of the reasons why it is hard to prove, the topic should still be researched more so we can get some answers!

Until then, period syncing is a nice way to bond with those close to you. And, like Winston, maybe we just feel the effects of a period when someone close to us is going through it with their own period. That could be how we are showing support. And that’s cute to think that there is someone you would sympathy PMS for.