Many myths have always circulated around menstrual cycle women. The latter begins on the first day of rules and ends on the eve of the next period. It lasts on average 28 days, but it can vary from one woman to another, or from one cycle to another. It is divided into 3 phases: the follicular phase avant l’ovulationthe ovulatory phase around the 14th day and the luteal phase after ovulation.
Among the ideas that revolve around the menstrual cycle of women, the latter would be, like the tides, influenced by the phases of the moon. Indeed, the resemblance between the duration of the lunar cycle and that of the menstrual cycle has encouraged questions around the links between these two phenomena. According to this theory, the lunar cycle acts as an external synchronizer of the menstrual cycle.
Are the menstrual cycle and lunar cycle associated? The answer from a study
A study published on April 10, 2024 in the journal Science Advances precisely looked at the potential existence of a internal biological clock which would regulate the menstrual cycle and which would be synchronized with the lunar cycle. To carry out this work, the scientists compared data from more than 27,000 menstrual cycles in 2,303 European women and nearly 4,800 cycles in 721 North American women, the majority of whom were under 35 years old.
At the end of the study, the researchers first noted the overall stability of the average duration of each participant’s cycles, despite differences in successive cycles. “A few shorter cycles could thus compensate for a series of a few longer cycles so that the total cycle length oscillates around the usual length of the menstrual cycle” detailed René Ecochard, one of the authors of the study, in a press release. “The duration of a cycle could therefore depend on the duration of previous cycles”, he concluded. Claude Gronfier, another author of this research, added that “the observation of this phenomenon argues in favor of the existence of an internal clock finely regulating menstrual cyclesitself synchronized by a cyclical environmental event”.
Lunar cycle: it would have a minimal but significant influence on the menstrual cycle according to scientists
Furthermore, the researchers also observed an occasional but significant association between the menstrual cycle and the lunar cycle. However, they noted a major difference in this synchronization between the data from Europeans and those from North Americans. Indeed, for European women, the cycle most often began at the waxing phase of the moon, while it began more often at the full moon for North Americans. “Despite this astonishing difference that we are unable to explain at the moment, the links identified between the lunar and menstrual cycles, due to their proximity to certain phenomena that we observe in chronobiologiesuggest that the periodicity of menstruation and ovulation could be influenced, in a modest but significant way, by the lunar cycle”, specified Claude Gronfier.
Synchronization of the menstrual and lunar cycle: how to explain this phenomenon?
Numerous hypotheses have been put forward by the existence literature to explain this minimal association between the menstrual cycle and the moon: an effect of light on physiology, the weight of gravitational attraction, or even a mechanism based on internal clock. If the researchers of the study did not agree on any definitive answer, they suppose that this synchronization could be the consequence of vestiges of the evolution of the human species, which would have acquired an internal clock close to that of the lunar cycle.
While there is still a lot of research to be done to decipher the link between the menstrual cycle and the lunar cycle, these first discoveries already represent a big step forward, according to the scientists in the study. “Confirming the existence of an internal clock coordinating the menstrual cycle, as well as the mechanisms involved in its synchronization, could make it possible to apply so-called ‘circadian’ medicine approachespersonalized, already used in oncology and for the treatment of sleep disorders or depression, for example, for problems such as ovulation disorders and of fertility”, concludes Claude Gronfier.
Sources :
- Evidence that the woman’s ovarian cycle is driven by an internal circamonthly timing system – Science Advances – 10 avril 2024
- Regularity of the menstrual cycle: a biological clock modulated by the moon? – Inserm – April 10, 2024
- The menstrual cycle – QuestionSexuality_
