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How the Full Moon Might Affect Our Sleep Cycle and Menstruation, According to Scientists

How the Full Moon Might Affect Our Sleep Cycle and Menstruation, According to Scientists

Two recent studies have shown that the moon's light can keep us up longer and women might temporarily have menses synced with the lunar cycle.

There are some pieces of knowledge passed down through generations that sound like old myths but there could be a grain of truth there. Humans have always looked to nature to provide guidance to live their daily lives, and the moon has had a big part in it. Now, it has been found that people go to bed later and sleep fewer hours before a full moon and menstrual cycles seem to temporarily synchronize with moon cycles.

From werewolves to mood swings, the moon has inspired many a lore, but two new studies have revealed that the full moon can indeed influence some parts of our lives. In a study published in the journal Science Advances, a team of scientists from the University of Washington, the National University of Quilmes in Argentina and Yale University have shown that sleep cycles seem to sync with the lunar cycle.

In the study, Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions, the scientists found that our sleep is most affected three to five days before the full moon.

Source: Getty Images | Photo by Dag Sundberg

"Moonlight intensity is sufficient to allow outdoor activities, and it is likely to prevent sleep initiation; in contrast, and importantly, it is unlikely to wake somebody who has already fallen asleep. In this context, it is primarily moonlight available during the first hours of the night that is more likely to drive changes in the onset of sleep," the study said.

To conduct the study, the team studied college students in the city of Seattle, Washington, and also those living in indigenous communities in northern Argentina. They needed the two different environments to study environments with a variety of access to electricity. They used sleep-monitoring wrist devices to monitor 98 individuals living in three Toba-Qom indigenous communities in Formosa, Argentina and used sleep data from 464 college students in the Seattle area, according to Space.com.

Source: Getty Images | Photo by Artpartner-images

They found that the connection between sleep and lunar cycles was more linked in communities without access to electricity. However, people living in places with electricity were also affected. "We see a clear lunar modulation of sleep, with sleep decreasing and a later onset of sleep in the days preceding a full moon," lead author Horacio de la Iglesia, a professor of biology at the University of Washington, said in a statement. "And although the effect is more robust in communities without access to electricity, the effect is present in communities with electricity, including undergraduates at the University of Washington."

Source: Getty Images | Photo by Roos Koole

The other study, Women temporarily synchronize their menstrual cycles with the luminance and gravimetric cycles of the Moon, also published in the journal Science Advances, scientists found that women whose menstrual cycles last longer than 27 days showed "intermittently synchronized with cycles that affect the intensity of moonlight," according to a statement, reported Space.com.

The study was a 32-year-long one and included 22 women. They found that the synchronization no longer worked as the participants grew older. The link was also reduced with more access to artificial light. They concluded that "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," according to the statement.

Source: Getty Images | Photo by Catherine McQueen

"At certain intervals, the rhythm of these individuals’ menstrual cycles appeared to oscillate in synchrony with the synodic lunar month. Menses onsets occurred close to its full moon or its new moon phase, with the full moon phase predominating," the research read.

References:

https://advances.sciencemag.org/content/7/5/eabe0465

https://www.space.com/full--moon-affects-human-sleep-menstrual-cycle

https://www.washington.edu/news/2021/01/27/moon-sleep/

https://advances.sciencemag.org/content/7/5/eabe1358

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