4 min readNew DelhiAug 1, 2026 03:01 PM IST
Tahira Kashyap had a recent brush with the popular concept of period syncing, where, as the name suggests, two women or more spending significant time together eventually get their period simultaneously. In her latest Instagram video, she talks about it in detail:
“I want to discuss a phenomenon that I came across. Women across the world are syncing. So this June, either women had their period twice, or they missed it. I haven’t deep-dived into it yet, but some are connecting it to the myth of two new moons, though there was only one new moon and one full moon this month. So, I asked my friends across cities, and those who responded in the groups, including me, experienced the same. Twice, or skipped,” she shared in the video.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
Dr Shilpa Agarwal, Consultant Gynaecology & Obstetrics and Fetal Medicine Specialist, Jaslok Hospital and Research Centre, Mumbai, says that menstrual cycle synchronisation, often called period syncing, refers to the belief that “individuals who menstruate and spend significant time together — such as roommates, close friends, family members, or partners — eventually begin experiencing their menstrual periods around the same time”.
Although this idea is widely recognised in popular culture, she says that scientific research has not found reliable evidence to support it.
How did the concept gain traction?
“The concept first gained attention after a study published in 1971 by researcher Martha McClintock. Her work suggested that women living together in a college residence appeared to develop more closely aligned menstrual cycles over time. She proposed that chemical signals, known as pheromones, might influence hormonal activity and contribute to this synchronisation,” shares Dr Agarwal.
However, subsequent research raised concerns about the original study. Agarwal elaborates further that scientists pointed out limitations such as a relatively small sample size, weaknesses in the statistical analysis, and a failure to account for the natural variability of menstrual cycles. “As a result, many researchers questioned whether the observed synchronisation reflected a genuine biological process,” she adds.
So, what’s the possible explanation?
According to Dr Agrawal, a more widely accepted explanation is based on normal cycle variation. “Menstrual cycles are rarely identical in length and are not always the commonly cited 28 days. In healthy adults, cycle lengths typically range from 21 to 35 days and may vary slightly from one month to the next,” she shares. And because of these natural differences, the “timing of two people’s periods may occasionally overlap purely by chance and later drift apart again”.
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Her belief is that these temporary overlaps can create the impression that their cycles have synchronised, even though no biological influence is occurring.
Quoting recent studies involving larger populations and improved research methods, Dr Agarwal said that they have generally failed to demonstrate consistent menstrual synchronisation. “The occasional coincidence of overlapping periods is most accurately explained by the natural variability of menstrual cycle lengths and the role of chance, rather than by hormonal communication or close social interaction,” she concludes.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.