According to the hypothesis raised by the researchers, the menstrual cycle can synchronize with the lunar cycle to increase the chances of reproduction, as happens in certain animals. It is the current changes in life with staggered schedules of the day/night cycle and the omnipresence of artificial lights, which has disrupted the process.
- The lunar cycle and the menstrual cycle of women were once synchronized according to researchers.
- As in certain animals, the synchronization of the two cycles makes it possible to optimize the chances of conceiving a child.
- However, with the rise of artificial lights and the shift in sunrise and sunset times, the two cycles have gradually become out of sync.
As the Moon can change the reproductive cycle in some animals, can it affect the menstrual cycle in women? Moon and menstrual cycle have resonated together for millennia and Charles Darwin, himself, the father of the theory of evolution, believed in the influence of the Moon on menstruation. According to researchers at the University of Würzburg (Germany), there is indeed a link between the menstrual cycle and the lunar cycle. The results of this study were published on January 27, 2021 in the journal Science Advances.
A rhythm that women would have lost
The researchers hypothesize that human reproductive behavior and the female menstrual cycle were synchronized with the Moon in ancient times, but our current lifestyles and artificial light have largely altered this synchronization.
“We know of many animal species whose reproductive behavior is synchronized with the lunar cycle to increase reproductive success, says Charlotte Förster, holder of the chair of neurobiology and genetics at the University of Würzburg. Given that women’s menstrual cycle is similar in length to the lunar cycle at around 29.5 days, a link seems likely.”. Older studies already evoked this link, by demonstrating for example that women whose cycle is synchronized with that of the Moon have a greater probability of becoming pregnant.
In order to verify the veracity of this hypothesis, the researchers studied the progress of the menstrual cycles of 22 women who had recorded the rhythm of their menstruation in a notebook, including one participant who noted her entire menstrual cycle for 32 years. This data was then compared to the lunar cycle in place at that time. “Scientifically speaking, the Moon exhibits three distinct cycles that periodically change its luminance and the gravity with which it strikes the Earth.analyzes Charlotte Förster. On the one hand, there is the change between the full moon and the new moon which takes place on average every 29.53 days with slight variations. On the other hand, the Moon does not circle the Earth in a fixed orbit. On the contrary, its position varies with respect to the equator. It is sometimes further north, sometimes further south. This cycle lasts 27.32 days. The third cycle is a little longer, with an average of 27.55 days. It results from the fact that the Moon accompanies the Earth in an elliptical orbit and is therefore sometimes closer, sometimes further away.”
Synchronization according to age
All these changes in the position of the Moon have an impact on the lunar light received by the Earth but also on gravity, as can be seen with the tides. Note, however, that the Moon does not affect all women. As the researchers report, on average, in women under 35, menstruation is synchronized with the full moon or new moon in just under a quarter of cases. Beyond the age of 35, this synchronization barely operates once in ten.
The synchronization of the lunar and menstrual cycles not only decreases with age, it also fluctuates depending on exposure to artificial light sources at night. Typical “night owls”, who go to bed late and leave the lights on longer, do not exhibit obvious synchronization with the Moon.
For Charlotte Förster and her colleagues, all these observations suggest that the human organism can react not only to rapid changes in gravity, as perceived by the equilibrium system, but also to slow and periodically recurring gravitational changes.
However, she remains aware of the limitations of her study due to the relatively small number of women studied. She hopes to develop a future study using a mobile phone to reach more people and better count menstrual cycles. This will make it possible to study the relationship between the menstrual and lunar cycles and the influence of artificial light on a large number of women throughout the world.
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