Researchers just figured out whether the moon actually affects your period

Ahh, periods. If you’re a regular HelloGiggles reader, you know that we love to talk about ’em. And why wouldn’t we? They’re kind of amazing — but they’re also a confusing, mysterious, and sometimes annoying part of femininity that people throughout history have tried to explain with theories and myths.


Lots of these old wives tales have since been debunked. We were surprised to learn that our menstrual cycles don’t actually sync up with those of our sisters, mothers, and female roommates. And according to the researchers at the Clue period tracking app, the moon doesn’t really have anything to do with your menstruation cycle. So sadly, you probably aren’t as in sync with Mother Earth as you thought you were.


Clue’s data science team analyzed the menstruation cycles of 1.5 million women—that’s 7.5 million cycles in all—and found little correlation between the lunar phases and the start of women’s periods.

“What you normally hear is that you ovulate around the full moon and get your period around the new moon,” said Dr. Marija Vlajic Wheeler, a data scientist at Clue. “Looking at the data, we saw that period start dates fall randomly throughout the month, regardless of the lunar phase.”

But when you look at the numbers, it’s no wonder that people thought there was some connection between the two. The average menstrual cycle lasts 29 days, while the average lunar cycle is 29.5 days.

That means statistically, one in two women will have their period +/- 3 days from the full moon or the new moon phase.

Before modern science, who wouldn’t believe that women were somehow in tune with the mysterious glowing satellite in the sky?

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