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For centuries, people have wondered whether the menstrual cycle was linked to the phases of the moon.

It’s easy to see where the idea came from. For starters, the average menstrual cycle lasts for about 29 days, the same as the lunar cycle.

We know that the moon controls the globe’s tides, so it isn’t so far-fetched to imagine that the moon might influence the internal tides of the menstrual cycle. While many scientific studies rebuke the hypothesis, the general public remains fascinated by the idea that menstruation and the moon may be linked.

For instance, on the day of the blood moon in 2019, people took to social media to express their curiosity and bewilderment at getting their periods during this astrological event.

So is there a link between menstruation and the moon? Let’s see what the evidence has to say.

One of the first people to suggest a link between menstruation and the moon was none other than Charles Darwin, who observed the link between the length of the menstrual cycle and that of the lunar cycle.

Since then, numerous studies have attempted to draw a conclusion about whether there’s proof of a real connection.

A famous 1986 study claimed that there was in fact a link. After testing 826 women, the researchers found that 28.3 percent of women began their periods “around the new moon.” Another study in 1987 supported this study’s findings.

A 1977 study found that women who began their cycle on the new moon had a greater chance of becoming pregnant.

But what do more recent studies say?

A 2013 study that analyzed 74 women over 1 calendar year found that there was “no evidence of synchrony.”

Even more recently, a 2021 study suggests that human menstrual cycles may once have been synchronized with the lunar cycle, but that artificial light and modern lifestyles have disrupted that link.

The study evaluated eight women who tracked their periods for 19 to 32 years. Five of the women studied synced up with the moon intermittently. For three of the women, the periods of synchronization occurred most frequently with the full or the new moon.

However, a 2019 study by the period tracking app Clue used data from 1.5 million users and found that there was no discernible link between the moon and natural menstruation.

According to the study, while around 30 percent of women do begin menstruating on or around the new moon, this doesn’t necessarily mean there’s meaningful connection.

“Statistically speaking, assuming that periods start at random times, about 1 in 2 people will have their period start ±3 days from either the full or new moon,” the study notes.

Evidently, there is a discrepancy in the research.

Clue’s study explains that statistically, every woman will sync up with the lunar cycle at certain points in their lives, but this could simply be a random coincidence.

It’s plausible that ancient humans were more in sync with the moon, but there’s no clear answer without further research.

What else (if anything) does the moon influence?

While it’s unclear whether the moon really does influence the menstrual cycle, other types of moon synchronicity have been noted.

A 2021 study found that both rural and urban communities experienced distinctive patterns of sleep oscillations throughout the lunar cycle. Around the time of the full moon, most people slept fewer hours and went to bed later, while during the new moon, people were more likely to sleep longer hours.

A 2017 study found that there may be a link between the moon and mental health, specifically bipolar cycles and the lunar cycle. Two of the study participants exhibited links between their mood cycles and their menstrual cycles, with both frequently starting on either the full or new moon.

In another 2017 study, however, no link was found between the full moon, or any lunar phase, and increased numbers of psychiatric episodes.

“If lunar effects exist, they are probably small or infrequent, making them difficult to validate statistically,” notes the study.

While the scientific community is still undecided on the potential synchrony of the moon and menstruation, numerous traditions and cultures believe there’s a spiritual link.

There are even modern rituals linking menstruation and the moon.

In a gathering called The Red Tent, women come together on the new moon to reflect and bond. The ritual is named after a 1997 novel of the same name that recounted how women in biblical times were ordered to conceal themselves from society during menstruation.

In Ancient Greek culture

The word “menstruation” derives from the Latin and Greek word for moon, mene.

In Ancient Greece, physicians believed that the moon and the monthly menstrual cycle were linked. During a woman’s period of menstruation, she was thought to be spiritually and mentally powerful.

In Indigenous cultures

In numerous indigenous cultures, there’s a history of menses being linked to the new moon.

In the Ojibwe tradition, menstruation is known as “moon time.” Traditionally, women take refuge at home during this time to rest and reflect.

“Women have great power during their moons,” Patty Smith of the Leech Lake Band of Minnesota Ojibwe told Rewire News Group. “As they bleed, they are sloughing off the accumulated experience and stress of being a woman. Some of those experiences are painful or may contain negative energy, so we want to be careful that we don’t interrupt that process.”

In the tradition of the Yurok tribe in California, moon time is also a prominent part of the culture.

In an article for the American Ethnological Society, Thomas Buckley spoke to a woman from the Yurok tribe who said that moon time is a time of strength.

It’s “the time when [a woman] is at the height of her powers,” she told Buckley. “Thus, the time should not be wasted in mundane tasks and social distractions, nor should one’s concentration be broken by concerns with the opposite sex.”

The women of the Yurok tribe also isolated themselves from men and family members during their moon time. They sometimes visited a “sacred moon time pond” where spiritual bathing rituals were performed.

Women of the tribe believe that they were all synced with the moon in ancient times.

According to the Yurok woman from Buckley’s article, if a woman from the tribe ever fell out of synchronization, she would “get back in by sitting in the moonlight and talking to the moon, asking it to balance [her].”

In Ayurveda and Hindu culture

Many Hindu and Buddhist traditions also point to a link between the lunar cycle and menstruation.

According to Ayurveda, blood, or rakta in Sanskrit, is believed to be governed by Chandra, the moon. Women were traditionally believed to be healthier when their cycles were in sync with lunar rhythms.

According to the medieval yogic text known as the Vasishtha Samhita, women were considered to be lunar in nature while men were considered to be solar. It was believed that the lunar cycle affected the various stages of menstruation.

Other spiritual traditions

Alicia Meek, founder of Wild Moon Sacred Cycles, practices Wicca and leads women in ceremonies to “preserve and carry forward ancient feminine practices while restoring cyclical consciousness on Earth.”

Though there’s no scientific evidence to support it, Meek believes that the four main phases of the lunar cycle correlate with the menstrual cycle.

  1. Menstrual, or New Moon
  2. Follicular, or Waxing Moon
  3. Ovular, or Full Moon
  4. Pre-menstrual, or Waning Moon

In addition, menstruating at particular times in the lunar cycle is believed by some to bring out certain attributes.

White moon cycle

According to Meek, those who are synced up to begin menses with the new moon and ovulation with the full moon are said to be on a white moon cycle.

Some believe that this type of cycle occurs when a menstruating person is “most fertile” or most ready to parent. It’s said to bring out a reflective quality.

Red moon cycle

People who find themselves menstruating on the full moon are said to be in the red moon cycle.

The spiritual meaning of having a period on the full moon, according to Meek, is an opportunity to embrace your passionate, outgoing, and sexual side.

Pink moon cycle

The pink moon cycle is associated with a time of transition and refers to when menses begins on the waxing moon.

The purple moon cycle

The purple moon cycle is associated with healing and refers to when menses begins on the waning moon.

Some who take part in ritualistic moon time practices believe that beginning menses on the new or full moon has benefits on mood, energy levels, and sense of spiritual connection, though this isn’t supported by science.

Track your cycle

Want to get to know your cycle and how it relates to the moon?

If you want to experiment with the link between your period and lunar phases, you can try tracking apps like:

You can take note of whether your cycle aligns with the lunar cycle. Then work with your natural flow to feel your best throughout your period.

For instance, take time to rest and reflect during the menstrual phase and use the ovulation phase to exert more energy and get things done.

Get synchronized

Although there’s no scientific reason to do so, believers say there may be ways to sync your cycle with the moon, including:

  1. Become more aware of the moon and its phases.
  2. Direct your energy in specific ways throughout the lunar cycle and your menstrual cycle.
  3. Sleep without digital light in your room.

By emulating the patterns of the moon, some say you may find that your period naturally syncs with lunar rhythms.

For instance, you can choose reflective and inward-looking activities during the new moon, and more social, connective activities during the full moon.

“If a woman wanted to switch to a white moon cycle,” Meek says, “then she would focus more on creating her home sanctuary, spending her time at home, and grounding inward during the new moon.”

There’s something magical and mysterious about the idea that your body might be working in sync with the moon.

While many scientific studies refute the idea of a connection, countless people and cultures have found spiritual meaning in honoring the link between the menstrual cycles and the cycle of the moon.

While there’s no strong evidence that there’s a connection, tracking your cycle’s relationship to the moon can’t hurt. It may simply be a way to connect more deeply to your body and to the natural world.

Meg Walters is a writer and actor from London. She is interested in exploring topics such as fitness, meditation, and healthy lifestyles in her writing. In her spare time, she enjoys reading, yoga, and the occasional glass of wine.