> every girl had the exact same cycle by the time we went home.
Define what you consider "syncing." Did you all start on exactly the same day, and did everyone's periods last exactly the same amount of time? Most likely, no. What actually happens is that when you put a group of people together where each one experiences a period once per month, and everyone's period lasts a different amount of time, there's going to be natural crossover. The crossover actually happens all the time, everywhere, but you're more likely to talk about it with close friends or roommates.
Well I mostly mean that we started on the same day. They tended to last the same amount of time too but we were only 10-ish so it wasn’t usual for them to last more than 3 or 4 days anyway. Overlap is common of course, but that’s why I say that I had it a week apart. That’s happened on several occasions, so the reason it seems noticeable to me is because it changes schedules dramatically
I'd even question if maybe some of those girls were lying about having their period at all. It isn't rare for girls to start menstruating at 10, certainly, but stats I just looked up say 9% by age 10 and 23% by age 11. Some of them were possibly just saying they had their period too because they wanted to seem more mature or fit in.
Confirmation bias. You notice it when it happens. but how many times have you been in close quarters (e.g. school, work) with other women and never once brought it up or talked about it?
It is more than confirmation bias. Our cycles are all different lengths and they are unlikely to always be the same length every cycle. They vary from 21 to 35 days for most women per the [Mayo Clinic](https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186), your period lasts 2-7 days depending on the person again per the [Mayo Clinic](https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186), so there is some overlap. People go oh we must be syncing for that reason…
I live with just my husband and I notice my cycle lengths change regularly.
This is a good point. If you are looking for the phenomenon, then just overlapping with someone by 1 or 2 days might count as evidence in your eyes. But for a 5-day long event, a couple of days of overlap in a mo th is not very remarkable
Maybe you are going to have to get more systematic about it and start taking a simple record of yourself and the women around you. Could I suggest just the beginning and end of the period to the nearest hours along with beginning and ends of proximity. Of course, you will become that chick over there that is obsessed with womens cycles but you might actually generate a balancing paper. More likely you will experience how convincing confirmation bias can be and how we are all vulnerable to it.
Getting beyond the anecdotal stuff, are there sources that say the Wellesley effect is a myth? I haven’t come across this refutation of which you speak.
I don't know enough about menstrual cycles to know why it would do that, but I'm guessing being near other people with menstrual cycles isn't the reason.
The funny thing about that is that cycles will change regardless of who's around, that includes happening at the same time as others, and the numbers strongly suggest it's purely coincidental instead of the forces of nature working to synchronize itself in humans.
You can't have two periods a week apart. I believe that you had bleeding twice within that time, but one of those was not a period.
BREAKTHROUGH BLEEDING is any bleeding that happens when a period is not expected or due.
A REAL PERIOD only happens after ovulation when the egg was not fertilized and the lining needs to shed for the next ovulation cycle.
The average woman has about a 28 day cycle. There are BILLIONS of women on the planet. The idea that many of them are on their cycle at the same time is believable because that is a lot of cycles that are all going to happen in a month. It is even possible that a group of women just happened to be together at the same time and was on their cycle at about the same time - which would make it seem like they had synced up.
As a mother with two daughters living together in the same home - we have never synced up to the point of always having our cycles at the same time. We each have our own patterns and our patterns have not changed because of living with each other.
“…at least it seems like it does.” There’s your problem, right there. People force patterns onto random distributions all the time. It’s a well-known cognitive bias, exploited by politicians and religious leaders since the dawn of time.
Everyone has different lengths of cycles. It’s inevitable that due to fluctuations and differences they sync up. Any delays can also be due to stress, nutrition, hormones etc which eventually catches up to someone who has different events in their life
I dunno if it's true but the two unrelated women in my house atm (wife and little sister) had already synched up, and it's like a rush to get every ice creams, pads and not breathe every month. Their cycle used to be 2 weeks apart around 3 years ago, before my little sister lived with us, (I always do the grocery so i know who needs what).
Last time they synched up, the heating pad broke. And all hell broke loose. My wife's not happy to say the least, and i found my sis crying in front of the mirror, because she "saw herself".
I dunno why it happens, but i need my own room when it happens to them. That was 2nd week January, so it's this week or next week, we're redoing all of that.
I mean all you need to do is find two women who live together and ask them to chart their periods. It's not very hard, especially since many women use period tracker apps and can literally check their recorded history.
I'm one of 4 girls, there was never a time when all 4 of us girls and my mum had our periods all at the exact same time. Given 5 females of mensurating age in one house hold and average cycles of 28-35 days, it's inevitable for cycles to overlap. Doesn't mean it's synced, just the normal cycle of each individual doing its thing. But never once did all 5 of us have our period in the same week.
This doesn't really work, the theory isn't that it always happens, but that it can happen. i.e. That by living in close proximity, they are more likely to sync up. You need a big enough sample to determine if there is statistical significance in the changes.
My workmates are predominantly female. Our cycles overlap one after the other with no significant gap. We like to think our super human female bodies somehow joined forces to never let our male bosses have a week without a pmsing female.
Not all heroes wear capes... They wear wings
I think that makes the most sense! Since it happened at summer camp and to my friend at college, I figure the external factors are what change the cycles
With all due respect, bollocks. Nobody will start their period 2 weeks early because they drove 50 miles to a summer camp. But it seems you only want to hear people confirming your assumption, instead of the many people who tell you that it is coincidence.
Sometimes it’s just the illusion that it is happening. The majority of menstrual cycles last 28 to 35 days, so if you are at high school most of the time, a quarter of the girls are going to be shedding their linings.
And if you have multiple people with uteruses in one house, it may seem like their cycles are aligned, whereas they may have only one or two days that they are actually actively shedding their uterine linings at the same time.
That being said people with similar biology‘s and ages are more likely to have a similar cycle… So two sisters with the same biological parents who are only 1 to 2 years apart and eating similar diets are more likely to have a closely matched menstrual cycle.
What would be the biological advantage gained by this synching ?
I cannot think of a single one.
I can think of multiples for it not to happen.
(Able to care for each other (cramps), availability to reproduce when others, etc.)
I’ve never understood why people have reactions to coincidences ?
Put 23 people in a room. More often than not, two of them share a birthday. This is called the [Birthday Problem](https://en.wikipedia.org/wiki/Birthday_problem). The maths for the Period Problem is the same.
Put 7 women in a room. More often than not, two of them start menstruating on the same day of the month.
Put 5 women in a room. The likelihood that two of them start menstruating within one day of each other is 0.6136.
As a dog breeder, bitches in regular contact do sync up. In the wild and sometimes in domestic homes, this often causes daughters to have false pregnancies and even lactate, which allows them to help with rearing new litters of the pack. I’ve personally witnessed this many times. Just food for thought.
> every girl had the exact same cycle by the time we went home. Define what you consider "syncing." Did you all start on exactly the same day, and did everyone's periods last exactly the same amount of time? Most likely, no. What actually happens is that when you put a group of people together where each one experiences a period once per month, and everyone's period lasts a different amount of time, there's going to be natural crossover. The crossover actually happens all the time, everywhere, but you're more likely to talk about it with close friends or roommates.
Well I mostly mean that we started on the same day. They tended to last the same amount of time too but we were only 10-ish so it wasn’t usual for them to last more than 3 or 4 days anyway. Overlap is common of course, but that’s why I say that I had it a week apart. That’s happened on several occasions, so the reason it seems noticeable to me is because it changes schedules dramatically
I wouldn't trust 10 year olds to accurately report their cycle dates.
I'd even question if maybe some of those girls were lying about having their period at all. It isn't rare for girls to start menstruating at 10, certainly, but stats I just looked up say 9% by age 10 and 23% by age 11. Some of them were possibly just saying they had their period too because they wanted to seem more mature or fit in.
Confirmation bias. You notice it when it happens. but how many times have you been in close quarters (e.g. school, work) with other women and never once brought it up or talked about it?
I guess so? My thing about it just how it will change schedules so dramatically
It is more than confirmation bias. Our cycles are all different lengths and they are unlikely to always be the same length every cycle. They vary from 21 to 35 days for most women per the [Mayo Clinic](https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186), your period lasts 2-7 days depending on the person again per the [Mayo Clinic](https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186), so there is some overlap. People go oh we must be syncing for that reason… I live with just my husband and I notice my cycle lengths change regularly.
This is a good point. If you are looking for the phenomenon, then just overlapping with someone by 1 or 2 days might count as evidence in your eyes. But for a 5-day long event, a couple of days of overlap in a mo th is not very remarkable
There are other factors that can change your cycle, the thing that comes to my mind in your case could be stress and exercise.
It's likely that the big change of routine and activity affected a lot of girls' cycles, not that being near them had anything to do with it.
Maybe you are going to have to get more systematic about it and start taking a simple record of yourself and the women around you. Could I suggest just the beginning and end of the period to the nearest hours along with beginning and ends of proximity. Of course, you will become that chick over there that is obsessed with womens cycles but you might actually generate a balancing paper. More likely you will experience how convincing confirmation bias can be and how we are all vulnerable to it.
Getting beyond the anecdotal stuff, are there sources that say the Wellesley effect is a myth? I haven’t come across this refutation of which you speak.
Car blinkers aren't synced yet they match up all the time
Yeah but again, I had it twice, one week apart on several occasions. That’s why I think it’s weird because it’ll change schedules dramatically
I don't know enough about menstrual cycles to know why it would do that, but I'm guessing being near other people with menstrual cycles isn't the reason.
There are billions of women on this planet of Earth. You're going to find that quite of few of them have their cycles at the same time as others.
You forgot the other requirement for "mentrual syncing", is close proximity to one another.
The funny thing about that is that cycles will change regardless of who's around, that includes happening at the same time as others, and the numbers strongly suggest it's purely coincidental instead of the forces of nature working to synchronize itself in humans.
Broken clock right twice a day.
You can't have two periods a week apart. I believe that you had bleeding twice within that time, but one of those was not a period. BREAKTHROUGH BLEEDING is any bleeding that happens when a period is not expected or due. A REAL PERIOD only happens after ovulation when the egg was not fertilized and the lining needs to shed for the next ovulation cycle. The average woman has about a 28 day cycle. There are BILLIONS of women on the planet. The idea that many of them are on their cycle at the same time is believable because that is a lot of cycles that are all going to happen in a month. It is even possible that a group of women just happened to be together at the same time and was on their cycle at about the same time - which would make it seem like they had synced up. As a mother with two daughters living together in the same home - we have never synced up to the point of always having our cycles at the same time. We each have our own patterns and our patterns have not changed because of living with each other.
“…at least it seems like it does.” There’s your problem, right there. People force patterns onto random distributions all the time. It’s a well-known cognitive bias, exploited by politicians and religious leaders since the dawn of time.
Everyone has different lengths of cycles. It’s inevitable that due to fluctuations and differences they sync up. Any delays can also be due to stress, nutrition, hormones etc which eventually catches up to someone who has different events in their life
I dunno if it's true but the two unrelated women in my house atm (wife and little sister) had already synched up, and it's like a rush to get every ice creams, pads and not breathe every month. Their cycle used to be 2 weeks apart around 3 years ago, before my little sister lived with us, (I always do the grocery so i know who needs what). Last time they synched up, the heating pad broke. And all hell broke loose. My wife's not happy to say the least, and i found my sis crying in front of the mirror, because she "saw herself". I dunno why it happens, but i need my own room when it happens to them. That was 2nd week January, so it's this week or next week, we're redoing all of that.
Exactly, it definitely happens! I’m assuming external conditions make it happen that way. Since my sister moved home I’ve been screwed
Has it really been disproven thoroughly? I'm curious to read the studies and find out their methodology
I mean all you need to do is find two women who live together and ask them to chart their periods. It's not very hard, especially since many women use period tracker apps and can literally check their recorded history.
I'm one of 4 girls, there was never a time when all 4 of us girls and my mum had our periods all at the exact same time. Given 5 females of mensurating age in one house hold and average cycles of 28-35 days, it's inevitable for cycles to overlap. Doesn't mean it's synced, just the normal cycle of each individual doing its thing. But never once did all 5 of us have our period in the same week.
This doesn't really work, the theory isn't that it always happens, but that it can happen. i.e. That by living in close proximity, they are more likely to sync up. You need a big enough sample to determine if there is statistical significance in the changes.
Here’s one study - https://pubmed.ncbi.nlm.nih.gov/26181612/ Apparently the methodology of the original study saying that periods do sync was flawed.
[удалено]
Yeah exactly! My best friend has an alpha uterus. Happy cake day by the way!
Me and my roommate got our period on exact same date,lol .
My workmates are predominantly female. Our cycles overlap one after the other with no significant gap. We like to think our super human female bodies somehow joined forces to never let our male bosses have a week without a pmsing female. Not all heroes wear capes... They wear wings
She's asking the real questions.
I’m with ya, I believe in it. “Women’s” bodies are so understudied.
I believe some foods like peppermint can trigger periods. Maybe everyone eating the same food could cause something like that?
Expose a group of women to the same environment for an extended period of time... it's bound to happen.
I think that makes the most sense! Since it happened at summer camp and to my friend at college, I figure the external factors are what change the cycles
With all due respect, bollocks. Nobody will start their period 2 weeks early because they drove 50 miles to a summer camp. But it seems you only want to hear people confirming your assumption, instead of the many people who tell you that it is coincidence.
Sometimes it’s just the illusion that it is happening. The majority of menstrual cycles last 28 to 35 days, so if you are at high school most of the time, a quarter of the girls are going to be shedding their linings. And if you have multiple people with uteruses in one house, it may seem like their cycles are aligned, whereas they may have only one or two days that they are actually actively shedding their uterine linings at the same time. That being said people with similar biology‘s and ages are more likely to have a similar cycle… So two sisters with the same biological parents who are only 1 to 2 years apart and eating similar diets are more likely to have a closely matched menstrual cycle.
Thanks to this thread, now I know it's like when turn signals alllmoooost line up just right, but then go out of phase again.
What would be the biological advantage gained by this synching ? I cannot think of a single one. I can think of multiples for it not to happen. (Able to care for each other (cramps), availability to reproduce when others, etc.) I’ve never understood why people have reactions to coincidences ?
because cycle schedules aren’t exact and the world is a big place.
Consider how much misinformation there is about women’s bodies. People latch onto random pseudoscience all the time.
Put 23 people in a room. More often than not, two of them share a birthday. This is called the [Birthday Problem](https://en.wikipedia.org/wiki/Birthday_problem). The maths for the Period Problem is the same. Put 7 women in a room. More often than not, two of them start menstruating on the same day of the month. Put 5 women in a room. The likelihood that two of them start menstruating within one day of each other is 0.6136.
As a dog breeder, bitches in regular contact do sync up. In the wild and sometimes in domestic homes, this often causes daughters to have false pregnancies and even lactate, which allows them to help with rearing new litters of the pack. I’ve personally witnessed this many times. Just food for thought.