For years, we believed our periods could magically synchronise with female friends and family members. But alas, it would appear it’s just a myth.
In fact, they’re far more likely to diverge over time.
Clue teamed up with Dr Alexandra Alvergne from the University of Oxford to look into the origins of cycle syncing, as well as past research. They then conducted their own study, analysing whether Clue users’ periods synced or not.
To date, no studies or mathematical analyses have proven the existence of cycle syncing. The first cycle syncing study, conducted in 1971, introduced the idea of the “alpha uterus”, a uterus with a strong hormonal pull that influences the cycles around it to ovulate and menstruate in unison.
Other theories include “socially mediated synchrony”, which claims that women sync to become sexually receptive at the same time, potentially preventing monopolisation from a single dominant male.
Clue used its data to investigate whether there was any truth behind cycle syncing.
The app reached out to users and asked if they thought their cycles had been syncing with someone who also used the app. They then asked what type of relationship they were in (ie. friends, siblings, parent/child, partners, roommates or colleagues), if they lived together, as well as whether they were on hormonal birth control.
They received over 1,500 responses and narrowed it down to 360 pairs of women with at least three cycles over a similar time period that they were able to review.
Researchers analysed a minimum of three consecutive cycles for each of those pairs and found that 273 pairs actually had a larger difference in cycle start dates at the end of the study than at the beginning of the study.
Only 79 of the pairs behaved the opposite way, with the gap between cycle start dates narrowing over the course of the study.
The study concluded that cycles don’t sync and are more likely to diverge over time.