We’ve been bleeding since, well, the beginning of time, and science has been trying to pinpoint how this actually happens among cohorts of women.
A study conducted in 1971 discovered that the longer women lived together, the closer their menstrual cycles became, according to Empowerher.
The phenomenon, described as the McClintock effect, was an example of how pheromones (chemical signals we emit unknowingly) effect our bodies.
The McClintock study was seemingly debunked by a 1990s follow-up study that observed women in college dorms, work settings, and among family members to see if there was synchronicity.
Researchers found periods synced-up some times but not others, leading scientists to believe it was happening at random.
They concluded we bleed so much that we will naturally overlap one another in cycles.
So it’s not really magic; more of the law of numbers and randomization.
Magic would’ve been a much more exciting explanation, though.
SOURCE: Empowerher | PHOTO CREDIT: Getty