No matter what the doctors say, women insist that they really do synchronize their menstrual cycles when they spend a lot of time together.
In response to a question by a listener of The Body Odd Podcast, Dr. Billy Goldberg explained that even though women think they're sharing cycles, it's just sheer coincidence, a statistical overlap during the normal 28-day cycle. "There's a lot of contradictory stuff, but there's no evidence that people do synchronize their periods," he said.
No matter, the ladies shared their stories of shared periods. A number of women credit the "alpha female" of a group for controlling everyone else's cycle, with one joking that she is the "dominant uterus" among her friends. Women in the military and co-workers experience it. A nurse in a hospital department calls it "very dangerous" when they all get into sync.
Families share — mothers say they influence their daughters' schedules — and sisters ending up with the same periods. As one e-mailed, "I have three sisters and we were synchronized while we were living at home. My dad once said it was nice because it was only one week of hell instead of a whole month."
Read on for more responses:
My friends and I joke that I have the "DOMINANT UTERUS!" No matter where they were in there cycles, I'd pull them onto mine! Within a month we'd be all together: laughing one minute, cranky, crying, and eating chocolate the next!
Lindsay, Mission, Kan.
In school I will tell my friends about the horrible cramps that I am having and how I might be a week early. My closest Friends B.P. and C.J. will tell me the same thing. That they are having bad cramps and that they started a week early. We are usually a day apart. It is so crazy how it happens!!
Bethany, Owendale, Mich.
During volleyball season in high school, because everyone was on the same schedule of eating and exercising, the entire team would pms one week then the next get week get our period. We'd all be asking each other for a tampon. Our coach brought in a huge box of toiletries so we wouldn't have to keep missing practice to run home and change!
Hannah, Bel Air, Md.
In college, it took three months for my roommate and I to get into the same "period pattern." We thought it was weird until we saw some articles on the internet about this phenomenon.
Eve, Camas, Wash.
I know for a fact that females' periods can be synchronized. Years ago (I'm 53 now) when I was 29, a friend was 36, and her daughter was 15, our periods were at various times of the month. However, after about six months of my husband and I spending a lot of time with this family, all three of us ended up with our periods at the same time and for the most part each of us had around 4 day periods. Odd, yes. True, yes. This is linked to the pheromones each of us have that are what draws men to us and that is what causes women who are together a lot to have synchronized periods.
Martha, Lakewood, Wash.
My college roommates and I used to talk about this! I am 49 years old and have 4 daughters ages 14-25. When my two oldest were teens, the 3 of us always managed to have our periods (and PMS) at the same time. As my third one became mature, and the other two moved out to go to college, her and I had them at the same time. Since that time I have had a hysterectomy, but my younger two now are in sync. My 25 year old recently moved back in with me, and she is now in sync with my youngest. My third is away at college and claims her and her roommate are now in sync. We've been talking about it for years!! I believe it!!!
Kathy, Denver, Colo.
Yes, I served 20 years in the military and found out that, if you work and live day to day with other women your periods do synchronize. Early in my career, I lived with six women in a room and we all had periods that synchronized at the same time. Also noticed daughter's and mother living in the same house hold synchronize or have periods at the same times. Amazing isn't it.
Dennise, Clarksville, Tenn.
Yes....with my my daughters when they all lived at home, and also with a best friend. The time of the month changed dramatically when my children began the experience.
Lin, Portola, Calif.
When I worked at a mall, my period use to be in sync with my manager and assistant manager's for a few months. Then in the last year, my sister, niece and I had our periods in sync. We would see each other practically every day as my dad was in the hospital and we'd go visit him. After a month of going together in the car, whenever one person started, the other two would start a day after or so.
Ann, Calif.
I think that women seem to have their periods synchronized with out even knowing it. Take for instance my sisters and myself. We all mark the start and ends of our periods on separate calendars, and as long as we all are participating in the same amount of physical activity we have noticed that we tend to fall within one week of the others' periods. The moment one of use is more or less active than the others the thing goes out of sync.
Grace, Niles, Ill.
I have 2 stories for you. While working in a small office with four female staff, one began using birth control pills and within three months all of us were on the same schedule — including the boss who was quite embarrassed that her period arrived almost two weeks earlier than expected. The second story, now that I have a daughter who is 12, she began her first period on the same schedule as mine.
Leslie
Every woman that I have either lived with or spent a lot of time with has within a few months started having menstrual cycles at the same time, give or take 2 days.
Nampo, Idaho
That's something nurses have known about for years! In my dept of our hospital we all get on the same cycle, regardless of birth control pills. Very dangerous!
Rhonda, Kan.
Yes, I sure have and all my coworkers hate me for it. Well, not hate, really. My period determines when everyone else's is going to be. For example: one of my co-workers, who is also my best friend, is on the Pill. It doesn't matter when she's supposed to have it, she has it two days after I start mine. We at first thought it was a fluke but we quit working with each other for six months and she didn't have a period at all. A week after we started working together again daily — I started my period. And so did she. So far, after working only a month at this place, I have switched two women's periods. Two down, about seven to go. God help those poor customers!!
Amanda, Odessa, Texas
Every time I work in a small office with several women, we end up being synchronized with our periods. We have noticed that the dominant personality is usually the period that dominates the synchronized periods.
JC, Provo, Utah
One place I worked, where we shared an open office, all 6 of us got our periods at the same time. My cycle was real regular and those that weren't ended up on my schedule. One of my colleagues was really grateful, because it was the first time she had ever been regular. I was always in sync with my sister and Mom too. (I started at 12 and am still going at 54, it was totally regular up til last year.)
Shelley, Henderson, Nev.
Okay, weird as this sounds, I have a non-spayed female cat whose cycles of being in heat are synced up with my period. This has been going on for several years now. I was out of town for three months recently, and my husband said she didn't go into heat the entire time I was away. VERY strange, but true.
Robin, Texas
When I was in basic Air Force training, by the end we were in-synch. My daughter and I are now synched as well. Don't know what it means.
Natalie L., Fayetteville, N.C.
Yes. we have 4 adult females in our home and their periods are close together. the two males in the house have no relief.
Ellie, Ware, Mass.
Absolutely. My sisters, niece, and I have been on the same schedule for years. The rule of thumb is whoever is on the strongest birth control will lead the rest of us. For example, I was on a low-dose birth control pill and began spotting. I had to adjust my pill schedule. It turns out I had adjusted to my niece and sisters.
Jennifer, Olathe, Kan.
At many different times in my life I've had friends whose periods synched with mine. I was probably the "alpha" due to the fact that I was always on birth control pills so my periods were extremely regular. I've had it happen with roommates in college, which stood to reason since we lived together. But as an adult I've also had it happen with several different women who were just good friends that I saw on a regular basis, even though we never lived in the same house.
Lisa P., Ft. Lauderdale, Fla.
Yes - right after college, my 3 friends and I backpacked throughout Europe. Most of us had just finished our periods or were currently on our periods, so we were happy that it would be only once that we would deal with it (the trip was for a month). One of my friends said that she had irregular periods, every two weeks. The rest of us had very normal periods. She ended up getting her period two weeks later, then I got my period a day later, then another friend got her period a day later. We thought our other friend would get hers too, but she didn't. Not sure why, but we were completely synchronized in Europe!!
April O., San Diego, Calif.
Absolutely! I shared a dorm in high school with 20 other girls, two to a room. We had three cycles going on... maybe three "alpha" females. Very strange, yet very predictable.
Elizabeth
I have three sisters and we were synchronized while we were living at home. My dad once said it was nice because it was only one week of hell instead of a whole month of hell.
Anonymous
When I left home for college my two sisters missed their periods for over a month. I was dubbed "Fertile Myrtle" by my mom when she also saw differences in her period cycle. At college, I never missed a period or was late/early. However, all three of my roommates either were late or early until we were all within about 2 days of each other. We were roommates for three years and all remained on the same cycle. I totally believe in synchronized periods and apparently I'm a "synch-er"!
Hannah, Colo.