Women’s Menstrual Cycles May Have Once Been Synced With The Moon, But Artificial Light Has Disrupted That
It was once a commonly held belief that women’s menstrual cycles were linked to the moon’s cycles, a theory that researchers from Julius-Maximilians-Universität Würzburg (JMU) think is highly likely. Although in this day and age, it appears that these cycles no longer always line up.
Were the cycles synced up due to the moon’s gravity? The moon, after all, does play an important role in moving our tides, but it also does another thing for our planet — it provides a source of natural light at night.
Instead of only the moon’s gravity, the JMU research team wondered if it was actually the moon’s natural light that impacted a woman’s menstrual cycle. After analyzing decades of data, the team found that perhaps the introduction of artificial light may have caused the moon and menstrual cycles to fall out of sync.
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Menstrual Cycles and the Moon
For this study, led by Charlotte Förster, a senior professor at JMU, the team collected 50 years’ worth of menstrual cycle data.
“The results showed that the menstrual cycles of women whose records were made before the introduction of light-emitting diodes in 2010 and the widespread use of smartphones were significantly synchronized with the cycle of the full and new moon,” Förster said in a press release.
The study results, published in Science Advances, show that since 2010, women’s cycles have been most synchronized in January, as this is when the sun, moon, and Earth’s gravitational forces are at their strongest. These findings have led the research team to believe that humans may have an internal “moon clock” that syncs with the moon’s natural light and its gravitational force. But the “moon clock” and moon cycle have been disrupted by artificial light.
Do Humans Have a Moon Clock?
Humans aren’t the only creatures that have moon clocks, according to Förster, and many species’ reproductive cycles are linked with specific phases in the moon cycle.
“Moon clocks are widespread in marine organisms, but have not yet been proven in humans,” said Förster in a press release.
The evidence that the moon plays a significant role in a woman’s menstrual cycle is also still up for debate. Regardless, the evidence from this study shows that women’s menstrual cycle timing has changed in the last 50 years.
The study also examines how the moon’s light can impact other body cycles, including the sleep cycle. Different research led by Basel researcher Christian Cajochen and Washington biologist Horacio de la Iglesia found that people tended to sleep less around the full and new moon, a phenomenon that applies to people who live in more urban areas filled with artificial light.
Improving Women’s Health
After further examination of the data, the research team believes that both moonlight and the moon’s gravity affect humans.
“However, our study shows that increased exposure to artificial light severely impairs the synchrony between the menstrual cycle and the lunar cycle,” said Förster in a press release.
The team found that the artificial light outshines the natural moonlight and can actually shorten a menstrual cycle. These non-syncing cycles only seemed to increase with the advent of LED lights and blue light from phone screens and computers, compared to traditional lighting like gas lanterns or regular light bulbs.
“LEDs have much higher energy than gas lanterns and light bulbs. In addition, they have a high proportion of blue light, to which our photoreceptors in the eye are particularly sensitive,” said Förster in a press release.
The research team hopes that these results can help improve women’s health.
“Since period length appears to be a possible age-dependent marker for female fertility, our findings could be relevant not only for human physiology and behavior, but also for fertility and contraception,” Förster concluded in a press release.
This article is not offering medical advice and should be used for informational purposes only.
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