To find it sad that our menstrual cycles are losing touch with the moon?

[Beachtastic]

OK, bit of a weird one, but this article published last month in Science Advances ("Synchronization of women’s menstruation with the Moon has decreased but remains detectable when gravitational pull is strong"), concludes that the increase of light pollution, and exposure to artificial light at night, has weakened the connection of our menstrual cycle with lunar cycles. It ends with "Because menstrual cycle length appears to be an age-dependent marker of female fertility, our findings may prove to be relevant not only to human physiology and behavior but also to fertility and contraception."

This makes me feel sad, a bit like finding out that turtle reproduction is messed up by artificial light because the hatchlings navigate to the water using the natural reflection of the moon and stars on the ocean’s surface. Instead of heading for the sea, they head for the local bar!

The effect on human reproduction is obviously less catastrophic, but still worth noting. The abstract says:
To increase reproductive success, many species synchronize reproductive behavior with a particular phase of the lunar cycle. The human menstrual cycle has also a period close to that of the lunar cycle, and recent studies suggest a temporary synchrony between menstrual and lunar cycles. Nevertheless, lunar influence on human reproductive behavior remains controversial. Here, we analyzed long-term menstrual records of individual women from the past 24 years and compared them with records from the past century. We show that women’s menstrual cycles recorded before the introduction of light-emitting diodes in 2010 and the extensive use of smart phones significantly synchronized with the Moon, while those after 2010 coupled to the Moon mostly in January. We hypothesize that the high gravimetric forces between the Moon, Sun, and Earth every January are sufficient for this coupling, while the increasing exposure to artificial light at night impinges on synchrony at other times.

Free PDF download from the link below, for anyone who understands science better than I do!

www.science.org/doi/10.1126/sciadv.adw4096

I know! Same here... 🤯

My 1st period was in 1967, even back then my cycle was @ least 31days(& always was till it wasn’t!)
What’s more i was in boarding sch. & none of us ever seemed to be even slightly in sync with moon phases or each other.

Eh? What about those of us who have or had 21 day cycles ?

I always felt lucky having a long cycle. It meant that I had at least one fewer period per year than most women!

OK I'm starting to feel a bit of a chump. I thought it was an interesting article, and I believe everything I'm told, especially when it's in a scentific journal and not the National Enquirer (mind you I'd probably believe that too, if I read it!).

Oh shush 🫣

Awww…. It happens to us all.

@Beachtastic if it makes you feel any better I went to boarding school and I had synced with all of my dorm mates (there for 10 years in total) and my daughter is also synced with her dorm mates. It's not a crazy idea that if you sync with 3 people you are in a room with every year you will think this is true. We did!

I tracked my cycles for years and they were always 31 - 33 days....and in fact over a year there was six x 31 days and 6 x 33 days, a bit like there being 6 x 30 and 6 x 31 day months in a year.

Me and my 3 female housemates all synced eventually when we lived together.

We only managed to live together for six months as it showed all of us how much our lives were run by our cycles - we'd be looking at the other person thinking 'why are they making such a mountain of this' then same thing would happen to the other person, and everyone would be baffled at them turning small things into crises 😂 Eventually we worked out it was hormones and there was one blissful month when we all synced.

😀

You didn't sync. You coincided.

In a house with four women, all of them will be with one week of each other's periods, statistically.

I know this is constantly dismissed by experts (men probably), but in my experience, it has always been true. As a teen both me and my sister synced with my mum, or it seemed we were always on at the same times. And the same when DSD lived at home we seemed to sync up, and now myself and both my dds all seem to have our periods at the same time.

I've never lived with as many women in as close proximity as sleeping in the same room with no contraceptives used, so I would really like to see any studies that use the same delimitations. I do wonder if the hormones in the pill and coil affect the pheremones in the same way they block the ability to be attracted to dissimilar MHCs.

I cannot believe the paper in the OP passed peer review. I have huge issues with its sampling and conclusions.

Firstly, it excluded anyone whose cycle wasn't 28 days long, nearly three quarters of the available women. So of course you're going to find patterns related to the moon, just by chance, when you do that. You're creating bias right right from the start.
It then showed that that women in the US and Europe synched to different parts of the lunar cycle. If the moon is such an influence, why arent all women synched to the same time. Why is there up to a week's difference? It even found differences in timing between French and Italian women. The moon is nearly 400,000km away. The distance between France and Italy is absolutely negligible in comparison, so something else must be going on.
And finally, back to sample size, several paragraphs refer to the American woman. Woman. Singular. There is no way conclusions can be based on a sample size of one.

"Peer review" really isn't all it's cracked up to be.

It's spoken like some kind of sacred mantra, but it's open to all sorts of errors, abuse, fraud, subjectivity and nonsense. As evidenced here.

Andrew Wakefield in The Lancet comes to mind!

I just came across it today and completely bought into the whole idea. I will never understand statistics 😞 (""lies, damned lies, and statistics")... and despite being quite long in the tooth, it has never crossed my mind that there was anything questionable about the menstrual cycle being tied in to the lunar cycle. It's just one of those things I've accepted since childhood. A bit like that myth about not swimming straight after lunch. My mum used to make us wait an hour!

It's not just statistics you need to get to grips with here, it's probabilities. For eg, it is highly probable that in a room of over n people, where n is about thirty, two of them will have the same birthday. (This is a fact.)

Just as it is highly probably that, of say five women living together, two of their cycles will coincide in any given month. (I made that one up, but you see what I mean.) And that may also coincide with a full moon. But it is not caused by the moon. Or the fact that they are living together.

And now, for the absolute comic that illustrates Correlation does not equal causation:

Ohhhh, it's all so disappointing! 😂 I thought I was onto something really interesting!

I accept that correlation ≠ causation, but can never quite get my head round how you work out probability (I'm rubbish at maths 🤡). And where the hypothesis is appealing, I'm quite happy to override probability in favour of whatever I want to see "proven."

Just as well I'm not a scientist, really 😉