One for the ladies...

[Adora]

A question:

When you move to a new group of living-mates (housemates, roomates, family changes etc) do you find that your menstration cycle changes to that of another woman in the house, or even that other females menstration cycles change to be more in-sync with yours?

It's just a little phenomenon that I think happens a lot but is never spoken about. I've heard of certain research in places to do with pheremones and such of "Alpha females" (the ones who dictate the cycle in the household) but there's not a lot of talk/research done on a wide scale.

I mean, I've had personal experience with it, even just being in some people's house for less than 2 weeks can sometimes change mine, or make other women's change to mine (heh heh heh). Just wondering if anyone else has had any experience of it. And yeah, if any of you fellas have witnessed it in groups of females, go ahead and share.

[viscousmemories]

I've heard enough women talk about it that I've always assumed it was true, but I don't have any scientific reason to believe it or personal experience with it. :D

[wade-w]

The phenomenon is called menstrual synchrony. The straight dope (http://www.straightdope.com/classics/a2_306.html) cites a study of 135 women in a college dorm. As far as I know, why this happens is not well understood.

[LadyShea]

Thanks for the link wade, interesting stuff.

I have had this happen with every female I have lived with. When there were 4 of us working together in a small office, we were all 4 on the same cycle, not fun for the men in the office when we were all PMSing! I always just assumed it was pheremone related.

[The Lone Ranger]

I dunno. Obviously, I have no direct experience, but it may one of those things that "everybody knows" is true when, in fact, it isn't.


Schank, J. C. Journal of Comparative Psychology. 2002. A multitude of errors in menstrual-synchrony research: replies to Weller and Weller (2002) and Graham (2002). 116(3):319-322.

Abstract:

This article replies to commentaries by A. Weller and L. Weller (2002) and by C. A. Graham (2002). The author of this reply argues that A. Weller and L. Weller merely defined away the problem of cycle variability for synchrony by assuming either that all cycles are 28-days long or that the expected difference between 2 cycles is 1/4 the mean of the cycles of 2 rhythms. In her commentary, C. A. Graham stated that A. Weller and L. Weller's later research did not use recall data, but the author of this reply shows that this is not true. Menstrual-synchrony research taken as a whole is plagued by a multitude of systematic errors that lead inevitably to the conclusion that there is no evidence for menstrual synchrony among women.

(My emphasis.)

One of Schank's major points is that the notion of menstrual synchrony is based on a very small number of studies, and most of the studies claiming that women living together synchronize their menstrual cycles have relied on very suspect data-gathering. In such studies, the women are sometimes simply asked if this happens, and allowed to compare notes with their housemates. As numerous studies have shown beyond any doubt, the human memory isn't anywhere near as reliable as we like to think, and when people are allowed to discuss whether or not a thing occurred in a group, dissenters tend to be quickly shushed, even if they're right.

Cheers,

Michael

[LadyShea]

Here's (http://www.moltx.org/bibliography.html) a bibliography of various studies to start some research.

Michael, that paper you posted was from a Psychology journal, and didn't conduct a study, simply reviewed other studies, correct? I don't know that his conclusions are necessarily gospel either as I read that at least one study actually brought the subjects to live together specifically to test the issue, so not all of them rely on self reporting.

Looks like there is evidence for and against, I don't think there is anything conclusive, and taking the pill or other homronal birth control can affect the group as well. All I know is it has happened to me.

[The Lone Ranger]

Quite correct -- Schank's study is a review of other studies, though he has apparently done some research of his own on the phenomenon, and the Journal of Comparative Psychology is actually quite a well-respected journal as I understand it.

Anyway, I don't know whether menstrual synchonry is a widespread phenomenon or not. I'd always heard that it was, and assumed so, until I actually looked it up and found that the evidence wasn't as ironclad as I'd heard.

Cheers,

Michael

[Edit for a typo.]

[LadyShea]

Here's an interesting Japanese study link (http://chemse.oupjournals.org/cgi/content/full/25/4/407)

It shows that there was a correlation between women that synchronized together within a study group (38% of the study group synchronized) and their ability to smell a putative pheremon.
All the women who were synchronized could detect 3-androstenol

[LadyShea]

Quite correct -- Schank's study is a review of other studies, though he has apparently done some research of his own on the phenomenon, and the Journal of Comparative Psychology is actually quite a well-respected journal as I understand it.

Yes, it's a very well respected journal, I just failed to see why a phenomena that would be chemically or physiologically based would be discussed in a psychology journal....but perhaps he thought it was psychosomatic or something.

Anyway, I don't know whether menstrual synchonry is a widespread phenomenon or not. I'd always heard that it was, and assumed so, until I actually looked it up found that the evidence wasn't as ironclad as I'd heard.

Quite right, all of this should be viewed with skepticism.

[The Lone Ranger]

Here's an interesting Japanese study link (http://chemse.oupjournals.org/cgi/content/full/25/4/407)

It shows that there was a correlation between women that synchronized together within a study group (38% of the study group synchronized) and their ability to smell a putative pheremon.

That's an interesting idea -- it has long been assumed that if menstrual synchrony occurs, it must have a pheromonal basis. Presumably, women who couldn't detect the pheromone(s) in question wouldn't be susceptible.

There's actually quite a bit of evidence that pheromones play a larger role in our behavior than most people would suspect. For example, it's been pretty convincingly shown that most women find men whose blood MHC factors differ from their own [and therefore are unlikely to be close relatives] more attractive than men whose blood MHC factors are similar to theirs [and therefore are likely to be close relatives].

Cheers,

Michael

[LadyShea]

That's an interesting idea -- it has long been assumed that if menstrual synchrony occurs, it must have a pheromonal basis. Presumably, women who couldn't detect the pheromone(s) in question wouldn't be susceptible.

Right, and it makes sense that so many other studies are inconclusive, because they didn't factor in that people differ in their ability to detect pheremones.

There's actually quite a bit of evidence that pheromones play a larger role in our behavior than most people would suspect. For example, it's been pretty convincingly shown that most women find men whose blood MHC factors differ from their own [and therefore are unlikely to be close relatives] more attractive than men whose blood MHC factors are similar to theirs [and therefore are likely to be close relatives].

Yes, it's really fascinating. Pheremone detection is at such a, I don't know, primitive level of our physiology, we aren't conscious of it.

I was reading just now, that regular contact with males has also been known to regulate and/or change a woman's menstrual cycle as well.

[godfry n. glad]

Um...

Leonard Shlain, author of Sex, Time and Power, a physician and writer, seems to take the issue of menstrual synchrony as a given. How long has the medical community accepted it? He cites Barbara McClintock, 1971 article "Menstrual Synchony and Suppression," Nature 229:244-45 in his comment:

Another feature indicative of Gyna sapiens' radical reproductive makeover is the mysterious way a close-knit group of women synchronize their menses. Nobel Prize laureate Barbara McClintock demonstrated that unconciously detectable pheromones emitted by alpha female in the group mediated this mysterious process.

pp52-53, Sex, Time and Power 2004, Penguin Books, NY

He then continues with:

Women who menstruate together must by necessity also ovulate together. Contemporary societies typically comprise large numbers of unrelated strangers constantly in flux who rare congregate in one place for any extended period of time. In contrast, ancestral women often lived most of their lives in close association with female members of their tribal group or clan whom they knew quite well. Our modern disruption in the living arrangements under which women lived for over 99 percent of our species' history has profoundly attenuated and obscured what was formerly a transformative evolutionary reproductive trait.

ibid, pg.53

godfry

[JoeP]

Anyway, I don't know whether menstrual synchonry is a widespread phenomenon or not. I'd always heard that it was, and assumed so, until I actually looked it up and found that the evidence wasn't as ironclad as I'd heard.
Of course not - loss of iron is to be expected. :runaway:

[Talulah]

There was a long thread on this on II a while back. Basically, the issue is the cycles were counted as "in sync" if they had an overlap of so many days. Statistically it is probable that you would overlap a few days with another woman's cycle ANYWAY. Another interesting point it that hardly any lesbians syncronize or claim to syncronize. This could be for several reasons, I suppose but the most probable is that lesbians have a more intimate knowledge of when each other are having their periods and therefore know that their cycles will converge for a while then grow apart then converge again.

However, I don't doubt it totally. When I was in college my 5 week cycle shortened to 4 weeks when living with my roommate and then went back to 5 weeks afterward (although even this "evidence" that living with Jennifer had an effect on my period is doubtful. It could have been hormonal changes that were independant of the situationn as now I am not exactly clockwork and haven't been for some time.), where it has remained even though living with diana. Diana has no effect on my cycle at all and ours are not syncronized in the least. Like I said, they come together for a few months then slowly grow apart then come back together because of our different cycle lengths.

[godfry n. glad]

Statistically it is probable that you would overlap a few days with another woman's cycle ANYWAY.

Probable? In what sense? Out of the entire set of females ovulating, the probability would be 5/29, wouldn't it? If you're saying that there are those that have 6/29, or 7/29 menses. Even an overlap of two days of 7 days would include only 12 days of the 29 day cycle. The likehood of all being synchonized being "coincidence" goes down as the number of women involved goes up. Right? So every subsequent overlap would have to overlap one of the two dates shared. What would be telling is a dormitory situation where a large number of menstruating women lived together on a relatively stable basis over an extended period of time...like a college dorm. I'd have to be more than just roommates. The effect would have to be noticeable beyond two women.

I'd say that's possible...but probable?

Am I missing something?

godfry

[Talulah]

I am not sure what you are getting at. In the famous study, only some of the women overlapped and I think they counted them as syncronized if they had a 2-3 day overlap. I don't remember. Then you have to know how long the study was, how many were on birthcontrol, how many were already having their periods at the same time. That throws off the statisics. Then, you would have to keep following to see how many continued to be in sync and how long it lasted.

I am not discounting the possibility of women affecting each other's periods, I just think the synchcronization is largely a myth.

[Talulah]

Plus, I have lived in a college dorm and people were having periods all the time from the evidence in the trashcans, although every few weeks it would seem to look like more were having theirs. But it wasn't the same week every month.