synchronised periods

LegacyUser

I live with 4 girls in rented accomadation and we have noticied that all our periods happen around the same time of the month. do you and your friends / flatmates periods synchronise? Do you think its strange? is there any reason why this happens us?

On the positive side at least one of the girls always has some nurofen!

vicecreamsundae

i read about this before that they don't actually synchronise at all. something about how statistically, there are going to be a few months where they seem synched, and then a few months when they're not, and then they will again, but theyre not ACTUALLY synching.

Faith

I don't know, years ago I spent two weeks on the Asgard (RIP). Nearly all of the girls got our periods at the same time - mine was over a week early. I wasn't supposed to have it while I was on board at all. It was bizarre.

LegacyUser

Quote from http://en.wikipedia.org/wiki/Menstruation
Beginning in 1971, some research suggested that menstrual cycles of co-habiting human females became synchronized. A few anthropologists hypothesized that in hunter-gatherer societies, males would go on hunting journeys whilst the females of the tribe were menstruating, speculating that the females would not have been as receptive to sexual relations while menstruating.[5][6] However, there is currently significant dispute as to whether menstrual synchrony exists

Yes me and my sister are sychronised. Not too sure about wikipedias explanation though as to why it happens.

Piste

This is all taken from "Elephants on Acid and other Bizarre Experiments" by Alex Boese:

Female rats housed together ovulate at the same time, which is attributed to pheromones.

During the 70s a student called Martha McClintock recruited 135 of her dorm mates to participate in a study whereby three times during the year they recorded data about the date of onset of their recent menstrual cycles, with whom they spent most of their time and whether they had been in the presence of men (the research was carried out at an all-female liberal arts college called Wellesly).

The results were that at the beginning of the year the menstrual cycles were all over the map but nine months later a high percentage of them were menstruating at almost the same time. The phenomenon was most pronounced amongst close friends.

McClintock subsequently did a further investigation in 1998 where she instructed 9 women to wear sweat-collecting pads in their armpits for 8 hours, she then wiped the sweaty pads beneath the noses of 20 other women (who didn't know what was being wiped under their nose). She found that the cycles of the women in the second group altered depending on whether they were wiped with the sweat of a woman early or late in her cycle. She concluded that pheromones contained in the sweat were responsible for this.

McClintock, M. K. (1971). "Menstrual Synchrony and Suppression." Nature 229: 244-45

ismiseuisce

I think it might be true.

I was in boarding school for my 6 secondary school years and I always used to notice that after a few months of living together (4-9 girls per dorm), the girls in the dorms that I was living in would end up all getting periods around the same time.

I don't know much about the science of it and it might just be coincidence but it did happen every year.

Panthro

Im a bloke that used to share a house with 4 ladies, I did notice that roughly once a month their mood seemed to change (buts thats because it was around the time of the month that the rent was due!hah!)
I do remember them talking about seeming to synchronise since moving into the house together, so there may be a grain of truth in it, but other than that I wouldn't have a clue.

up for anything

I always used to have a 24 day menstrual cycle but for two years when I worked in on particular office it changed after the first few months to a 28 day cycle and there were about 12 out of 14 of us down one end of the floor we worked on who would start our period within the same two days every month. When I left there my cycle went back to 24 days.

Scarinae

When I was younger I used to get my period at the same time as my mum and my sister. Where I live at the moment I appear to be in sync with one of my flatmates, but not the other two, funnily enough the one I'm in sync with would be the one I spend the most time with.

eimearcmh

I lived with 3 other girls at one stage, we were/are all friends and quiet close. One month one of the girls thought she was pregnant and thought her period was late. We had been pretty much in synch before so we had a fair idea who was due next. She was convinced she was pregnant bless her, but we tried to comfort her and explain that she normally gets her period the day after *Mary* and Mary hadn't hers yet. Mary was due the next day and sure enough my friend had her's the day after that. Bit of relief there!

baby and crumble

yeah, i went to boarding school for 6 years and all of us in my dorm ended up synced. i tell you, the lc year was a nightmare. everyone hormonal and stressed at the exact same time!!!!

I've lived in a few houseshares, when I shared with all girls, and we spent nearly all our time together, it seemed our cycles got closer together, but not exactly synced. Sharing with two girls where we mostly did our own thing, there was no evidence of this. Similiarly two other house shares where there were two of us girls, and two guys, it didn't happen at all. I'm not sure if I believe it, if the first time wasn't just coincidence, or whether it was directly related to the amount of time we actually spent together.

Malari

I've never noticed this, but then I suppose I assume that most girls I've lived with are on the pill. But maybe they aren't. What percentage of young women in Ireland is on the pill I wonder...?

LizT

This happened to me, mine came over a week early and I discovered that one of girls I was on a trip with had hers at the same time. I wouldn't normally think anything of it but my period is almost never early and if it is, it's only a day or two early!

Ms. Chanandler Bong

http://www.guardian.co.uk/society/2005/aug/25/health.lifeandhealth

LegacyUser

Interesting article catreyn - I def think that there is some truth that women who work / live very close together get their periods synchronised. However I wudnt really discuss my period with work colleagues - wud you?

My sisters periods seem to last 4 days whereas mine last 5 or 6 days but we both seem to have our period pretty much at the same time of the month - alot of hormones! Neither of us are on the pill.

Wibbs

It's a funny one if true(and I reckon there's something to it). Why would nature want a group of women to sync? What advantage does it give them, or the men they're around? Human's are unusual in that the female hides her fertility, except at the time of menstruation. The theory being that the man will hang around more, because he's never sure when she's fertile. You would think along those lines it would be better for women to vary all over the place?

Ms. Chanandler Bong

I know of a bunch of women who were living together & on the Depo-Provera injection - by the time the next injection was due, they were at each other's throats & the doc asked one of them whether she was sharing a house with anyone else who was taking it. She mentioned that there were 5 of them all taking it. Doc told her that she wouldn't give her a script for it as it affected the hormones of women around her as well & if there were five of them taking it in the one house...!
I know my boyf is able to tell when I'm due, knows how long my cycle is an' all which struck me as a bit freaky until the day I was listening to Ray Darcy & himself & Will were telling Jenny & Mairead when they were due their periods!:D Their reactions were priceless!

Xiney

Wibbs wrote: »

It's a funny one if true(and I reckon there's something to it). Why would nature want a group of women to sync? What advantage does it give them, or the men they're around? Human's are unusual in that the female hides her fertility, except at the time of menstruation. The theory being that the man will hang around more, because he's never sure when she's fertile. You would think along those lines it would be better for women to vary all over the place?

That's because you're thinking about it from the man's advantage point of view Wibbly

It's ok, we won't throw you out.

If women's periods are synced, then the man's opportunity to knock more than one woman in the same group up is limited - assuming he'd have to dedicate some time and attention to courting her (at the time in question I believe a suitable gift was an antelope or something) before she'd agree to bear his children, he wouldn't have the ability to go out and get more than one cave girl preggers.


Edit: I should add that this is something I just thought of in the past five minutes and I have no actual basis in fact - it's just another way of looking at it.

_Whimsical_

Piste wrote: »

This is all taken from "Elephants on Acid and other Bizarre Experiments" by Alex Boese:

Female rats housed together ovulate at the same time, which is attributed to pheromones.

During the 70s a student called Martha McClintock recruited 135 of her dorm mates to participate in a study whereby three times during the year they recorded data about the date of onset of their recent menstrual cycles, with whom they spent most of their time and whether they had been in the presence of men (the research was carried out at an all-female liberal arts college called Wellesly).

The results were that at the beginning of the year the menstrual cycles were all over the map but nine months later a high percentage of them were menstruating at almost the same time. The phenomenon was most pronounced amongst close friends.

McClintock subsequently did a further investigation in 1998 where she instructed 9 women to wear sweat-collecting pads in their armpits for 8 hours, she then wiped the sweaty pads beneath the noses of 20 other women (who didn't know what was being wiped under their nose). She found that the cycles of the women in the second group altered depending on whether they were wiped with the sweat of a woman early or late in her cycle. She concluded that pheromones contained in the sweat were responsible for this.

McClintock, M. K. (1971). "Menstrual Synchrony and Suppression." Nature 229: 244-45

This effect is actually known as the "Wellesly effect" after the women's college in which it was first studied.

I read that their initial research was on hamsters and provided some compelling results to suggest that periods do synchronise among females in the same environment. They came to the conclusion that pheromones were responsible for this effect in the following way

Firstly they placed two hamsters in the same air tight clear box/cage sharing the same water & food and found that their periods synchronised after a short time.

Then they placed a partition in the air tight cage so the two hamsters were unaware of each others presence and were not sharing the same food & drink supply but did share the same air. Again their periods synchronised.

Then they placed each hamster in a seperate air tight cage side by side so they could see each other but did not share the same supplies or air and found the periods of these hamsters did not synchronise.

Then they put a partition between these two cages so they hamsters could not see each other and were not sharing supplies but they put an air pipe leading from one cage to another so that the same air was circulating between the two cages. Again periods synchronised between these two hamsters. So it was clear that what was stimulating the synchronising of periods was air born so must have been pheromones.

Obviously they did many multiples of the above experiments before deciding they were valid results.

This example is often used in books and lectures on neurobiology to illustrate how your society can influence your individual biology. It's quite freaky when you actually think about that.

Another interesting thing that the research on human women in Wellesly college revealed was that generally the periods of women in a social group tend to synchronise with the women who is most socially dominant/influencial within the group!
I don't think thats thoroughly researched though so it might not be true.

I can't find a source for all that now but I'll look later. It's mainly from a lecture series on The Neurobiological Origins of Individuality by Robert Sapolsky who is highly respected in his field. He is professor of Biological Sciences, and Professor of Neurology and Neurological Sciences, and by courtesy, Neurosurgery, at Stanford University.

SugarHigh

How close to someone elses does it have to be for it to be considered synced up?

Even if you were to go by start date alone the max difference could really only be about 2 weeks.

Wibbs

SugarHigh wrote: »

How close to someone elses does it have to be for it to be considered synced up?

Even if you were to go by start date alone the max difference could really only be about 2 weeks.

True. I think they have to be in very close proximity over time. An ex of mine moved with three other women and after about 6 months her's went in sync with them. Interestingly (well for me being a curious bugger about such things), they all synced, but they synced to one of the women. Either by moving up to her date or dropping back. Hers didnt change and she was like clockwork apparently. Which in that admittedly teeny tiny sample may suggest that there might be an "alpha" woman with the strongest hormone/pheromone output that others sync to? Personality wise she was among the quietest but maybe signals were the strongest.

How did I hear all this? They had a party one night and I was the only bloke and we were all well hammered so it came out in convo.

squeakyduck

This happened to me and two of my flatmates on first year. We were all going around moaning and holding our stomachs one night, and I was like I came on today.....oh me too, ME three! We all had a laugh about it, curled up under a duvet with a movie and loads of chocolate!

It's mad to think it happens though!

Casey_81

Thats mental - does kinda explain my messed up cycle though..

I work in IT, so am mostly surrounded by guys.

But since i started my a new job about 5-6mths ago it has all settled down.. must have synched up with some of the girls that work there...

Herbal Deity

Birthday problem, anyone?

Something similar going on here I reckon. The probability of a number of women having their period at a similar time is a lot higher than it might seem intuitively.

Maybe there's some pheremonal basis though, *shrug.

spurious

I'm amazed so many people seem to not know this happens.

Wibbs

Wibbs wrote: »

It's a funny one if true(and I reckon there's something to it). Why would nature want a group of women to sync? What advantage does it give them, or the men they're around? Human's are unusual in that the female hides her fertility, except at the time of menstruation. The theory being that the man will hang around more, because he's never sure when she's fertile. You would think along those lines it would be better for women to vary all over the place?

Maybe the other women have a higher chance of getting a guy then you want to step on and outdo them! I mean biologically speaking not "steal her bf" kinda way
I suppose it if varies all over the place you don't know who'll have first pick

Faith

Herbal Deity wrote: »

Birthday problem, anyone?

Something similar going on here I reckon. The probability of a number of women having their period at a similar time is a lot higher than it might seem intuitively.

Maybe there's some pheremonal basis though, *shrug.

Right, but this refers to your cycle actually changing to synchronise with another person, not just that you randomly have the same cycle from the get-go.

Herbal Deity

Forgive me if I'm wrong, but cycle lengths vary, and almost always aren't 100% regular 100% of the time, no? Therefore, your periods will almost certainly begin to correlate with other women at some points, while not doing so at other points.

And what defines synchrony? Starting on the exact same day? Within 1/2/3 days of each other? Given that the max time between two women starting their periods will be about 14 days, how liberal one is with their definition of synchrony can massively impact the probability of it being a random occurrence.

I'm not saying that they don't naturally sync due to pheromones, the jury is still out on that, but I think that there's quite a high potential to think that they are syncing when they are not.

Basically, what vicecreamsundae said. Or this.

Hersheys

I synced with my housemate. But then we both started on the pill and she had issues initially and ended up on a different schedule to me, but without the pill, we'd probably sync again!