On this day in 1969, humans walked on the moon. So let's take the opportunity to talk about the moon and its relationship to menstruation. Does the moon influence our menstrual cycles at all?
The word "menstruation" is itself linked to the ancient Greek word for moon: "mene". However, this link is indirect: "mene" influenced the Latin word "mensis" for month, and "menstruation" comes from this word.
Both the lunar cycle and the menstrual cycle are roughly the same length - around 29 days long. So for someone with a regular cycle of 29 days, they will be largely synced with the moon's phases. But does this mean that one is influencing the other?
It makes sense to believe that the lunar cycle influences the menstrual cycle. The gravitational influence of the moon's alignment with Earth causes the large bodies of water to move with the tides - and what are we but big ol' bags of water?
Both tides and the light of the lunar cycle have an effect on animals - for example, coral spawns on a full moon.
But there isn't actually any strong evidence that the moon is influencing our periods.
Research linking the menstrual cycle to the lunar cycle doesn't show any clear consensus as to which phase of the moon is responsible for menstruation: some show menstruation starting at around the full moon, others at around the new moon.
This means research cannot demonstrate a mechanism for how the moon is influencing our cycles - while there is arguably a benefit for either being fertile at a new moon (complete darkness) or a full moon (most light), it can't be both on a 29 day cycle!
It's worth noting at this point that neither the lunar cycle nor the menstrual cycle are exactly 29 days: the lunar cycle is in fact 29.5 days long, and the menstrual cycle can be anything between 21 and 40 days, and varies both within the same person and between people.
The huge variance in the length of the menstrual cycle suggests that the moon's influence, if it exists at all, is pretty minimal.
The similarities between the length of the lunar cycle and average menstrual cycles can sometimes muddy the waters in interpreting objects from the past - for example, was the Ishango Bone a menstrual tracker, a lunar calendar, or something else entirely? https://masto.ai/
It's also unclear as to whether people in the past consistently saw links between the menstrual cycle and the lunar cycle. For example, many traditions have a female moon deity... but many others, such as Japanese, Egyptian, Norse and Irish have a male moon deity.
Pliny, in his altogether entirely wrong explanation of periods, didn't mention anything about phases of the moon (though did say that period sex in an eclipse was risky) https://masto.ai/
Ultimately, the human menstrual cycle syncing up with the lunar cycle is probably more of a coincidence than anything else - much like menstrual synchrony among people that live together https://masto.ai/
Nevertheless, it can be comforting to feel part of a bigger whole. It can be helpful, if your cycle is 29-30 days, to look up and see a menstrual tracker right up there in the sky. But it's also good to know that you're not experiencing tidal forces in your uterus.
@vagina_museum I was quite happy that my cycle was around 35 days, one more week without the curse. Then it got shorter and shorter in the peri menopause, ending up at roughly 21-23 days. That was a right pain. Anyway, definitely no influence by the moon or friends, despite sleeping with open curtains. 🤪
@vagina_museum Do you know whether aggregated data from period tracking apps has/could be used to investigate this? (And whether that data is made available? Privacy nightmare obviously - would need to be done incredibly carefully)
@vagina_museum do ponto de vista puramente matemático é bem difícil a influência ser gravitacional, mas, além de sacos de água, temos uma consciência bem ativa, criativa e influenciável. Acho que algum instinto pode ativar o período inconscientemente quando a lua está cheia...
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