The mysticism of the Moon and that of female bodies - in an "era in which medicine was in its infancy - led the Greek philosopher Aristotle to maintain, in the fourth century, that:"Menstruation tends to occur naturally during the waning moon […]. For this time of the month it is colder and wetter due to the decay and disappearance of the Moon ".
, and also a connection between menstruation and the moon. This could be based on the similar duration between menstrual cycles and lunar cycles.
A question of timing
A complete revolution of the Moon around the Earth takes 27 days, 7 hours and 43 minutes. A cycle of moon phases, during which the amount of the lunar surface we are able to see from Earth increases and decreases, takes 29.5 days. The length of menstrual cycles can range from 25 to 30 days, with the median duration of a menstrual cycle being 28 days.
The Chinese study
A 1986 study conducted by the Gynecology Department of Canton Traditional Chinese Medical College in Guangzhou seemed to show the link between menstrual and lunar cycles. The research studied the cycles of 826 participating women, aged between 16 and 25, over "4 lunar months in different seasons". The focus of the research "was based on the concept of traditional Chinese medicine that human physiological rhythms show synergism with other natural rhythms".
The results. A high percentage of women had menstruated around the new moon. This led the Chinese researchers to deduce that the periods of ovulation (the moment in which the egg is released from the ovaries and moves towards the fallopian tubes, which normally occurs on the fourteenth day of the cycle, if this lasts for 28 days) tended to coincide with the full moon.
The most recent studies
However, more recent research contradicts the idea that menstrual cycles often synchronize with the phases of the moon. For example, a 2013, one-year retrospective study that appears in the journal Endocrine Regulations - did not find "the synchrony of the phases of the moon with the menstrual cycle". This study tracked 980 menstrual cycles in 74 women of reproductive age for one calendar year.
A more recent study, commissioned by the company that programs the Clue cycle tracking app in 2016, concludes that the synchrony between menstrual and lunar cycles is a “myth.” This research, which analyzed over 7.5 million cycles menstrual, suggests that periods most likely "do not synchronize with the lunar cycle." The researchers collected data on menstrual patterns from 1.5 million Clue users, which were subsequently analyzed. The results: From the data they have, period start dates fell randomly during the month, regardless of the moon phase.
, however, suggests that there may be a synchrony between moon phases and menstrual cycles. This small-scale study analyzed the menstrual patterns of 22 participants who tracked the start of their period up to age 32. The data showed that those whose menstrual cycles were longer than 27 days had intermittent synchrony with two of lunar cycles: the luminance cycle and the gravimetric cycle.
- The luminance cycle refers to the different intensity of the moon's light as its position relative to the Sun changes and passes through its different "phases", from the new moon to the full moon.
- The gravimetric cycle refers to the cyclic difference of the Moon's attraction to Earth as it orbits our planet. Since the Moon's orbit is elliptical, it is sometimes further away from the Earth, sometimes it approaches.
Its cycle from perigee (when it is closest to Earth) to apogee (when it is farthest from Earth) lasts 27.5 days. Depending on where it is in its orbit, the Moon exerts a different gravitational pull on different parts. of the Earth.
A third lunar cycle - the tropical month or the mean time of the Moon's revolution from anywhere in its orbit to that same point - also seemed to be linked to the "beginning of the period, albeit" to a lesser extent, "according to the study's authors. .
The team also noted that as menstrual cycles intermittently synchronized with lunar cycles, the likelihood of synchrony faded as participants grew.
The researchers observed that the moon's light intensity cycle appeared to be the most influential lunar cycle in terms of its effect on the onset of menstruation. In ancient times, fertility and moon phases were connected, but with the modern lifestyle. , the relationship has changed significantly.
humans - the "body clocks" that regulate our biological patterns - refer to the cycles of our natural environment. For example, they looked at fluctuations in blood melatonin levels during the menstrual cycle.
Levels of melatonin - which is a key hormone for regulating circadian rhythms, and in particular the sleep-wake cycle - peak just before menstruation begins and decline, overall, the closer a woman approaches menopause.
There is also some evidence to suggest that the full moon affects sleep, essentially disrupting the duration and quality of sleep. Furthermore, it seems evident that artificial light can interrupt sleep-wake cycles and have a negative impact on the duration and quality of sleep. How, then, does artificial light affect women's natural synchronicity with lunar cycles over time? Artificial light affects various aspects of circadian rhythms, but there is no scientific evidence on how it could interfere with menstrual cycles.
