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Synchronised Menstrual Cycles- True or Not?

Mr Manifesto

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I'm a male, for those of you who don't know, or can't tell despite my deep, masculine voice. I've been wondering about the veracity of claims that women who live together will, over time, synchronise their menstrual cycles.

I checked this website which said,

Most women have either heard of or experienced the phenomenon of bleeding in synch with their fellow sisters. But what causes it? And how does it affect your fertility?

There is very little scientific research on this topic so it is difficult to arrive at one definitive answer. It is probably a combination of factors that has changed and evolved over the centuries.
Click to expand...

There's something about 'little scientific research' that sets off the ol' warning bells.

Part of me thinks that, because the 'bleeding' stage of menstruation takes place over several days, a period of overlap between two women is seen as 'synchronisation'. So, if woman A starts menstruating on Monday, is finished by Wednesday, and her flatmate starts on Wednesday... Hey, synchronisation?

But what do I know? Thankfully, I won't have the dubious pleasure of experiencing mestruation. Does anyone know if this phenomena really exists, has been scientifically studied?
 
I don't know if there's been any actual research. I know when I lived with female roomates (and once in an all-female dorm) I never noticed any particular synchronization with anybody else.

The problem with that, however, is that pretty much everybody I knew (including me) was on the pill, and when you take the pill, your menstrual cycle is regulated by the hormones in the pill, so there's no way for the synchronization (if it could actually happen) to come about. Unless of course two girls were on the same schedule for the pill. That would also create a false sense of synchronization.
 
well, my understanding was that it was one of two identified human pheromones. i'm stuck at home, but will try to get you the official paper later today.

the two pheromones are:
--contact pheromone that assists parent/child bonding
--mentrual inducing pheromone

basically, any of the "pheromones" offered for sale to make guys sexy are unlikely to work (or at least not in the way you want them to :))
 
[on the pill and glad for it... so should Mr Manifesto, or he would be dead by plastic spoon]
 
My wife (a skeptic, BTW) tells me that this indeed happens, especially when the group she's working with is relativley small, and they see each other quite regularly. She said she's experienced this almost every place she's worked.

Avian
 
Found it!

Regulation of ovulation by human pheromones
Stern K, McClintock MK
NATURE
392 (6672): 177-179 MAR 12 1998

Document type: Article Language: English Cited References: 30 Times Cited: 121 Explanation

Abstract:
Pheromones are airborne chemical signals that are released by an individual into the environment and which affect the physiology or behaviour of other members of the same species(1). The idea that humans produce pheromones has excited the imagination of scientists and the public, leading to widespread claims for their existence, which, however, has remained unproven. Here we investigate whether humans produce compounds that regulate a specific neuroendocrine mechanism in other people without being consciously detected as odours (thereby fulfilling the classic definition of a pheromone). We found that odourless compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary (underarm) compounds from the same donors which were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing-hormone surge of the recipients and lengthened their menstrual cycles. By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.

KeyWords Plus:
WOMENS MENSTRUAL CYCLES, OVARIAN-CYCLE, ESTROUS SYNCHRONY
 
I do know that twice in my life, once when I worked for a few years with about 6 other women, and another time when I was younger and lived for a year with three other women, we did indeed become synchronized.
 
Good lord. Now that women are joining the armed forces in larger numbers , would a female-only battalion constitute a biochemical weapon of mass hysteria??
The thought of several thousand women, trained to kill, armed to the teeth and simultaneously suffering from PMT is too awful to contemplate.
 
Some menstrual cycles occur every 21 days, some are 28, some are 12, some 23, etc... it makes sense if they all come together one day... and and cycle at the same time. Does this happen consistently? Also, some cycles last 7 days, some 3 days, some 14 days, etc.... are these effected too?
 
I can't quote any scientific evidence. The governing force that would cause this would be pheromones which are chemical signals that are put off by a person. They are rather like hormones, but instead of working within the system, they work without.

Now for my own belief is based completely on anecdotal evidence - I grew up in a house with 4 females, and we all menustrated at the same time although my menustral cycles were much shorter and lighter than my mother and sister. A friend of mine and I who went to college together, had the same classes and the spent an inordinate amount of time with each other, our cycles eventually began to match to the day.

As for scientific evidence, well, I have none nor have I seen any research for this, and my anectdotal evidence may be mere coincidence. I will say from my perspective that I hypothisize that it is true.
 
Julia said:
I do know that twice in my life, once when I worked for a few years with about 6 other women, and another time when I was younger and lived for a year with three other women, we did indeed become synchronized.
Click to expand...

I have the same experience and interestingly the effects of PMS syndrome were much milder.One should expect that our area would be "heavily mined", I mean, all those women experiencing PMS syndrome together but nope we didn't have any problems of sort. Now that I work with a bunch of men that's another story...
 
Soapy Sam said:
Good lord. Now that women are joining the armed forces in larger numbers , would a female-only battalion constitute a biochemical weapon of mass hysteria??
The thought of several thousand women, trained to kill, armed to the teeth and simultaneously suffering from PMT is too awful to contemplate.
Click to expand...

This is such a ridiculous stereo-type. People, yes even women [gasp], have good days and bad days and their own opinions and actions, and ED forbid we actually have a bad day or be in a bad mood because it is MASS HYSTERIA!! Pfeh.
 
That's another interesting problem. Not all women have the same menstrual cycle. I know one woman who mestruates every two weeks. So how is it possible to have synchronisation?
 
Re: Found it!

um, this seems to have been missed before.

bug_girl said:
Regulation of ovulation by human pheromones
Stern K, McClintock MK
NATURE
392 (6672): 177-179 MAR 12 1998

Document type: Article Language: English Cited References: 30 Times Cited: 121 Explanation

Abstract:
Pheromones are airborne chemical signals that are released by an individual into the environment and which affect the physiology or behaviour of other members of the same species(1). The idea that humans produce pheromones has excited the imagination of scientists and the public, leading to widespread claims for their existence, which, however, has remained unproven. Here we investigate whether humans produce compounds that regulate a specific neuroendocrine mechanism in other people without being consciously detected as odours (thereby fulfilling the classic definition of a pheromone). We found that odourless compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary (underarm) compounds from the same donors which were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing-hormone surge of the recipients and lengthened their menstrual cycles. By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.

KeyWords Plus:
WOMENS MENSTRUAL CYCLES, OVARIAN-CYCLE, ESTROUS SYNCHRONY
Click to expand...
 
so, to elaborate:
ovulation syncs, but that doesn't mean that ~menstruation~ syncs. Depending on where you are in the cycle when you are exposed to another woman's pheromone, it will take some time to adjust.

some women seem to be "queen bees," and emit large amounts of pheromones. i had a friend who we all avoided like the plague when she had her period, since we would all immediately start too.
 
bug_girl said:
so, to elaborate:
ovulation syncs, but that doesn't mean that ~menstruation~ syncs. Depending on where you are in the cycle when you are exposed to another woman's pheromone, it will take some time to adjust.

some women seem to be "queen bees," and emit large amounts of pheromones. i had a friend who we all avoided like the plague when she had her period, since we would all immediately start too.
Click to expand...

And how this is explained in terms of... Natural behavior. I don't know the right term so bare with me. All I want to ask is how and in what way Nature profits from this synchronization?
 
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