Lunar and Geophysical Influences on the Menstrual Cycle: A Recent Study
A โคrecent study publishedโ in โข Science Advances investigated the relationship between human menstrual cycles and lunar rhythms, finding continued, though โevolving, synchronization. Researchersโ analyzed data fromโค multiple sources, including historicalโ and contemporary menstrual cycle tracking data, and Google trends searches related toโ menstrual โขpain, toโฃ explore the influence of lunar cycles – synodic, โanomalistic, and tropical – on menstruation.
The study โconfirmed a โขhistorical trend of menstrual onsetโ aligning withโ lunar phases. Specifically,โ a tendency โforโ cycles to synchronize with โฃthe full or new moons was observed, particularlyโค around the winter solstices and duringโฃ lunar standstills, periods of heightened gravitational andโฃ light influence. However, this synchronization with the synodic month (approximately 29.5 days) has weakened since 2010, coinciding withโ the increased prevalence of artificial light at night.
Despite the โdiminishing influence of the synodicโค month, synchronization with the anomalistic month โ(~27.55 days, โbased on the Moon‘s elliptical orbit) and the tropical month โ(~27.3 days,โ based โคonโ the โSun’s apparent โmovement) persisted, and in some cases, even strengthened after 2010.โ This suggests a potential increase in theโค relative influenceโ of gravitational cyclesโค as โlight-basedโค cues became less dominant.Synchronization with โฃbothโฃ the anomalistic and tropical cyclesโข was mostโข pronounced during the winter solstice, when Earth is closest to the sun (perihelion).
Geographical variations were also noted. In Italy, menstrual onset exhibited a bimodalโข pattern, peaking two days โbefore both the full and new moon, potentially โฃlinked to higher light โขpollution levelsโ in the โdata collection โregion. Germany, though, showedโข a single peak โ1.5 daysโ before the full moon.
Longer lunar cycles โalsoโ demonstrated an โฃeffect. โMenstrual onset โคshowed โคstrong synchronization with the full moon during minor โlunar standstills, coinciding with the Sarosโ series #137 eclipse sequence, which amplifies โgravitational effects. โ Major lunar standstills, conversely, showed weaker synchronization, biased towards the new โขmoon.
Supporting evidence came โfrom Googleโ Trends data,โ revealing peaks in searches for “period pain” and related โขterms at perihelion in several countries. Interestingly, this pattern โขwas not global,โฃ being absent in italy, France, and New Zealand, and occurring in theโ Southern Hemisphere duringโข summer months, challenging the hypothesis that moonlight alone โขdrives the observed synchrony.
The researchers conclude thatโ both lunar luminescence and gravimetric cycles influence human menstrual cycles, with the menstrual cycle acting as an internalโฃ clock partially aligned with theseโ external rhythms.They propose that โขgravity may โexert its influence indirectly through broader geophysical effects.Moreover, theโ study suggests that menstrual cycles were likelyโฃ more strongly synchronizedโค with the moonโข in the past,โ before theโฃ widespread adoption โขof artificial lighting.
Source:
Forster, C. H., Domene, โฃE. D., Montagnese, J. J. and S., et al. (2025). Synchronizationโฃ ofโฃ women’s menstruation with the Moon has decreased but remains detectable when gravitationalโค pull is strong. Science Advances.doi: https://www.science.org/doi/10.1126/sciadv.adw4096
