Do Women’s Periods Sync Up With Each Other Because Of “Alpha Pheromones”?

How do women start syncing together? Is it really because their pheromones have some type of energy-sensing system going on, referred to as the McClintock Effect, or do most women just happen to menstruate around the same time because of the moon cycle?

By Anna Hugoboom2 min read
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I remember a girl in college who definitively stated she was the alpha female in her suite and that when she hit her period, her roommates knew to be ready to start theirs. She considered herself to be the hormonal alpha female figure. While this certainly sounds convenient and may give friends a feeling of closeness, there could be more at play here.

An alpha figure in a social setting is definitely a thing, but the science jury is still out on whether or not women’s pheromones actually stimulate a menstrual synchrony in other females. Some girls in a living situation might sync, but they might have specific sleep, exercise, and health habits in common that would influence their menstruation, especially regarding family members who were raised the same way. But then there are plenty of female housemates who menstruate at different times, and there are also some friends who don’t live together who seem to start their periods in the same week. So, what the heck is going on then?

Pheromones are chemical signals that we send to other humans around us. Although some people champion the possibility of a dominant energy’s pheromones influencing others in their environment, there is no solid scientific proof to support this theory. 


However, there is evidence that the moon cycle can indeed influence women’s hormonal cycle. Many women sync with the moon cycle because of the lunar gravitational pull on the Earth. Besides possible factors of hormonal fluctuations and deficiencies, scientists’ speculations as to cycle irregularities include atmospheric pressure as well as electromagnetic fields (these are influenced by the moon). 

Women who lived in rural areas with less artificial light were more synchronized with the lunar cycle.

Studies indicate that some women who don’t menstruate parallel to the lunar cycle are probably “night owls” who experience lots of artificial light pollution that interferes with their circadian rhythm of sleep and prevents their hormones from tapping into the moon cycle. This research also showed that women who lived in more rural areas with less artificial light were more synchronized with the lunar cycle than women who lived in cities because the urban lights and electronic blue light could override the natural light of the moon and disrupt their body’s cues to this natural process. 

How Many of Us Are There Again?

The second scientific synchronization factor is probability. Remember, there are a lot of females on this planet, billions actually, so chances are high you will be menstruating at the same time as at least a few other women you encounter. Many women may end up menstruating during a similar (or, for some, the exact same) time through coincidence. Although a moon cycle is 28 days, some women may have something closer to a 30-day or 35-day cycle due to hormone levels and may overlap with those in their social circle or living proximity. Some women have health conditions that delay their cycles, or they may be deficient in progesterone and experience a shorter cycle. This is why one roommate who has a longer cycle could overlap with her roommate who may have low progesterone and a shorter cycle, but this doesn’t necessarily mean they synced up or that one is the alpha female. 

Closing Thoughts

80-95% of women believe in menstrual synchrony, but newer studies show that periods syncing up are more likely to be from probable coincidence, similar hormones to begin with, fluctuations in hormonal levels due to health or deficiencies, and/or the influence of the moon cycle. Although many women will tell you they sync with others, they probably have other lifestyle similarities that play a role in their periods more than “alpha pheromones.”

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