Women's menstrual cycles temporarily synchronize with Moon cycles

January 27, 2021

An analysis of long-term menstrual cycle records kept by 22 women for up to 32 years shows that women with cycles lasting longer than 27 days intermittently synchronized with cycles that affect the intensity of moonlight and the moon's gravitational pull. This synchrony was lost as women aged and when they were exposed to artificial light at night. The researchers hypothesized that human reproductive behavior may have been synchronous with the moon during ancient times, but that this changed as modern lifestyles emerged and humans increasingly gained exposure to artificial light at night. While previous research suggests that women with menstrual cycles that most closely match lunar cycles may have the highest likelihood of becoming pregnant, lunar influence on human reproduction remains a controversial subject. To address this long-standing mystery, Charlotte Helfrich-Förster and colleagues examined long-term data on the onset of menstrual cycles spanning an average of 15 years, including records from 15 women age 35 or younger and 17 women over 35. To uncover any times during which the women's menstrual cycles occurred in sync with lunar cycles, the researchers displayed the data as raster plots (graphs that show time-based relations) along with fluctuations in the moon's cycles. The researchers found that most women's menstrual cycles aligned with the synodic month (the time it takes for the moon to cycle through all its phases) at certain intervals. Menstrual cycles also aligned with the tropical month (the 27.32 days it takes the moon to pass twice through the same equinox point) 13.1% of the time in women 35 years and younger and 17.7% of the time in women over 35, suggesting that menstruation is also affected by shifts in the moon's gravimetric forces. Furthermore, the researchers observed greater synchronization between lunar and menstrual cycles during long winter nights, when women experienced prolonged exposure to moonlight. While the moon's luminescence and gravimetric cycles each appeared to only weakly affect menstrual cycles on their own, the findings suggest that these cycles exhibit a stronger effect together, with menstrual cycles most in sync with lunar rhythms when the moon is nearest to the Earth. (Note: This study includes one author (Ignacio Spiousas) in common with the study by Casiraghi et al., highlighted in this same issue of Science Advances.)
-end-


American Association for the Advancement of Science

Related Artificial Light Articles from Brightsurf:

Light from rare earth: new opportunities for organic light-emitting diodes
Efficient and stable blue OLED is still a challenge due to the lack of emitter simultaneously with high efficiency and short excited-state lifetime.

Guiding light: Skoltech technology puts a light-painting drone at your fingertips
Skoltech researchers have designed and developed an interface that allows a user to direct a small drone to light-paint patterns or letters through hand gestures.

Painting with light: Novel nanopillars precisely control intensity of transmitted light
By shining white light on a glass slide stippled with millions of tiny titanium dioxide pillars, researchers at the National Institute of Standards and Technology (NIST) and their collaborators have reproduced with astonishing fidelity the luminous hues and subtle shadings of 'Girl With a Pearl Earring.'

Seeing the light: Researchers combine technologies for better light control
A new technology that can allow for better light control without requiring large, difficult-to-integrate materials and structures has been developed by Penn State researchers.

Artificial brains may need sleep too
Neural networks that become unstable after continuous periods of self-learning will return to stability after exposed to sleep like states, according to a study of simulated spiking neural networks, suggesting that even artificial brains need to nap occasionally.

Controlling artificial cilia with magnetic fields and light
Researchers have made artificial cilia, or hair-like structures, that can bend into new shapes in response to a magnetic field, then return to their original shape when exposed to the proper light source.

Artificial pieces of brain use light to communicate with real neurons
Researchers at The University of Tokyo, University of Bordeaux and at Ikerbasque have created a way for artificial neuronal networks to communicate with biological neuronal networks.

Scientists use light to accelerate supercurrents, access forbidden light, quantum world
Iowa State's Jigang Wang continues to explore using light waves to accelerate supercurrents to access the unique and potentially useful properties of the quantum world.

Artificial synapses on design
Memristive devices behave similarly to neurons in the brain. Researchers from the J├╝lich Aachen Research Alliance (JARA) and the technology group Heraeus have now discovered how to systematically control the functional behaviour of these elements.

Synthetic chloroplast enables light-powered CO2 fixation in artificial biological systems
Combining microfluidics and the natural photosynthetic membranes from spinach plants, researchers have developed 'synthetic chloroplasts,' which are capable of mimicking complex and life-like photosynthetic processes, a new study reports.

Read More: Artificial Light News and Artificial Light Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.