Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: paul.fr on 19/04/2007 00:11:30

Title: Period syncronisation
Post by: paul.fr on 19/04/2007 00:11:30
I've heard it said that, when women live together, students for example, their periods syncronise! Why does this happen and how dangerous would it be to visit them at the wrong time of the month?
Title: Period syncronisation
Post by: Carolyn on 19/04/2007 00:30:23
I don't have the answer to the first part of your question, but wanted to add they don't have to live together.  My best friends and I (in total 5 of us)were inseparable and generally had the same cycle.

As far as the second part of your question.  I would say it could be life threating! [;D]  I WILL NOT visit my daughter at her dorm during that time.  It's a real b****fest.
Title: Period syncronisation
Post by: neilep on 19/04/2007 02:05:52
Don't you girlies follow the lunar cycle ?.....well..I have heard that some girlies do !

This has got me curious.

Do you girlies - for the most part- keep to the same menstrual cycle regularity through out your lives ?....at regular intervals ?

I do realise there are times when it is conditioned to happen..ie: when taking certain contraceptive pills (or all of them..I don't know).

have you had  " periods" when you've menstruated every two weeks ?..three weeks...six weeks etc ?...
Title: Period syncronisation
Post by: Carolyn on 19/04/2007 02:19:04
Can only speak from my personal experience, and it's been a long time since I was a teenager.  I seem to recall that during my teenage years every few months it was off by a day or so, which made my cycles change a few times a year.  This was true for my friends as well. Once I started taking contraceptives, they stayed regular....that's about all the bc pills were good for. [:)]
Title: Period syncronisation
Post by: another_someone on 19/04/2007 03:10:47
Lots of things can affect periods.

Girls who have too little fat (anorexics, or some sports women) will simply switch off their periods.  Some women have complaints such as PCO that can go from no period to ultra heavy periods, and switch between.  Then there are birth control pills that only give one period every 3 months.  Those not on contraceptive pills can have all sorts of reasons why their periods will have all sorts of variability both in intensity of periods, and in regularity of them, their being delayed, or missed (hence the issue about whether women can be pregnant without realising it - if you are one of those women who do not have clockwork periods, then you may not notice that you have missed a few periods).
Title: Period syncronisation
Post by: another_someone on 19/04/2007 03:18:44
Incidentally, many women are not capable of tollerating the contraceptive pill, so that is not for them an option as to how to get their periods back to being regular.
Title: Period syncronisation
Post by: Karen W. on 19/04/2007 05:18:33
Mine were always irregular and heavy. They would hit between cycles of 20 days to 36 days depending. A severe cold flue or stress can also delay said period. The one time I used birth control I took them without fail and have a wonderful blond haired 19 year boy to show for it! Our primary birth control was Rhythm.. I hate pills and they did not work!LOL for me.. as such I chose to not give them the second chance! LOL

As for womens periods. I work with many women, every time we get a new co worker my period messes up or is delayed. within two months we are all 7 of us having our periods the same week when we all started out on separate cycles..! I really don't get it, but know it does happen.. It is a weird phenomenon!
Title: Period syncronisation
Post by: rosy on 19/04/2007 14:15:06
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I've heard it said that, when women live together, students for example, their periods syncronise!

It's true. I live with three other girls...
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Why does this happen
Mechanistically, I believe it's down to different pheromones being emitted at different times of the month. The effect can be replicated by getting women to smell sweat from another woman at a different point in the cycle each day (by rubbing as swab on her upper lip, I think).
I guess it might be evolutionarily useful to be synchronised with nearby women since if you've got a bloke and there's a week each month when he can't get you pregnant it's probably as well as if in that same week he can't wander off and get some other woman pregnant (in terms of getting maximum resources for your child and not having to share your man's foraging capabilities with some other woman)... anyway, that's today's piece of dodgy speculative anthropology...
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and how dangerous would it be to visit them at the wrong time of the month?
Depends. Sometimes dangerous, sometimes merely inconveniently tearful.
Title: Period syncronisation
Post by: paul.fr on 19/04/2007 14:26:12
Depends. Sometimes dangerous, sometimes merely inconveniently tearful.

Rosy, i think i would prefer a lot of angry women to the tearful type.
Title: Period syncronisation
Post by: Karen W. on 20/04/2007 04:43:54
Depends. Sometimes dangerous, sometimes merely inconveniently tearful.

Rosy, i think i would prefer a lot of angry women to the tearful type.

I cry but there is generally one day I am grouchy. tears are better, less stress! emotions and tears help clean out bad sad or other feelings and relieve tension!
Title: Period syncronisation
Post by: another_someone on 20/04/2007 15:47:07
I guess it might be evolutionarily useful to be synchronised with nearby women since if you've got a bloke and there's a week each month when he can't get you pregnant it's probably as well as if in that same week he can't wander off and get some other woman pregnant (in terms of getting maximum resources for your child and not having to share your man's foraging capabilities with some other woman)... anyway, that's today's piece of dodgy speculative anthropology...

Thinking about this a bit, I would make a slightly different guess.

Firstly, I would guess that it is not menstruation that is synchronised, but ovulation (which then inevitably means that menstruation will follow in synch).  One reason why I think this more likely is that most species do not naturally menstruate - menstruation comes about from ovulation that has not lead to pregnancy, and the more common event in nature is that ovulation will be followed by pregnancy.

Secondly, as you say, it is about competition for men, but it is as much about males being attracted by the pheromones associated with ovulation.

There is, I believe, some evidence that there is a higher probability of a woman being raped during the period she is ovulating.  As unpleasant a side effect as that may be, it does imply that ovulation can change male behaviour, even in humans (it certainly can in other species).

Clearly, if 5 females are living together, without a male, then all 5 of them ovulating together will increase the likelihood of attracting a nearby male than would only one female ovulating on her own.

Where 5 females are in a harem, with a resident male, then the first female who is ovulating will probably have access to the male when he is freshest, but equally, another female ovulating very soon afterwards might yet be able to compete with the first - but the fifth female to ovulate might have a disadvantage.

The other possibility is that if all five females ovulate at the same time, the male will pretty much have is hands (maybe not his hands) full coping with it all, and if he cannot cope with it all at once, it gives some of the females a chance to play away.  The smell of 5 females ovulating will no doubt have also attracted males other than the dominant male in the harem, all seeking to sneak in and have their own opportunity while the dominant male is busy elsewhere.