Research ArticlePHYSIOLOGY

Women temporarily synchronize their menstrual cycles with the luminance and gravimetric cycles of the Moon

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Science Advances  27 Jan 2021:
Vol. 7, no. 5, eabe1358
DOI: 10.1126/sciadv.abe1358

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  • RE: Women temporarily synchronize their menstrual cycles with the luminance and gravimetric cycles of the Moon
    • Ioannis ILIAS, MD, PhD, Elena Venizelou Hospital, Athens, Greece

    We were impressed with the study of Dr Helfrich-Förster et al. [1].

    It would be interesting - for the sake of completeness - to indicate how data were handled during time periods of travel and/or stays at different locations (if any).

    Furthermore, the gravitational influence seems more "potent" than that of moonlight per se; even in rural settings - albeit with access to electricity or artifical light - a 40 Watt table lamp gives at least 14 lx whereas moonlight gives 0.32 lx maximum [2].

    Incidentally, in an older study of 980 menstrual cycles in a calendar year in 74 women (and analyzed with cross-approximate entropy) we did not find any association between lunar phases and the menstrual cycle [3]. However, the study by Dr Helfrich-Förster far surpasses this number in menstrual cycles and is thus more reliable.

    References
    [1]. Helfrich-Förster C, Monecke S, Spiousas I, Hovestadt T, Mitesser O, Wehr TA. Women temporarily synchronize their menstrual cycles with the luminance and gravimetric cycles of the Moon. Science Adv 2021; 7: eabe1358,
    DOI: 10.1126/sciadv.abe1358
    [2]. Kyba C, Mohar A, Posch T. How bright is moonlight? Astronomy & Geophysics 2017; 58: 1.31–1.32. DOI: 10.1093/astrogeo/atx025.
    [3]. Ilias I, Spanoudi F, Koukkou E, Adamopoulos DA, Nikopoulou SC. Do lunar phases influence menstruation? A year-long retrospective study. Endocr Regul. 2013; 47: 121-2. DOI: 10.4149/endo_2013_03_121.

    Competing Interests: None declared.

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