Is the full moon change how we sleep? Does it synchronize with menstrual cycles?
What may sound like old school myths may have a truth. People go to bed later and sleep less hours before a full moon and menstrual cycles apparently temporarily synchronizing with lunar cycles, scientists have found in two new studies.
Throughout history, humans have associated our daily lives with the changing sky, specifically the changing faces of the moon. Lore surrounding the phases of the moon ranged from full moons inciting werewolves to the cycle of the moon affecting how we feel and our daily mood.
But oddly enough, it seems that some of these long stories have roots in real science.
Related: The moon: 10 surprising moon facts
Sleep with the full moon
In a study published today (January 27) in the journal Science Advances, a team of scientists from the University of Washington, the National University of Quilmes in Argentina and Yale University show how sleep cycles appear to change with the lunar cycle.
They found that in the days before the full moon, people tended to go to bed later and sleep less hours. For this work, the team studied university students in the city of Seattle, Washington, and also among those living in indigenous communities in northern Argentina, two different environments where there is a variety of individual access to electricity due to how artificially light the participants.
Using wrist monitoring devices, they studied 98 individuals living in three indigenous Toba-Qom communities in Formosa, Argentina, and also used sleep data from 464 university students in the Seattle area (the data from the university students was originally collected for a separate study.).
The team found that although the relationship between sleep cycles and lunar cycles is a bit clearer in communities without access to electricity, it appears that the connection still occurs in areas with electricity as well.
“We are seeing a clear lunar modulation of sleep, with sleep declining and falling asleep later in the days before a full moon,” said lead author Horacio de la Iglesia, a professor of biology at the University of Washington. said in a statement. “And while the effect is more powerful in communities without access to electricity, the effect is present in communities with electricity, including undergraduate students at the University of Washington.”
In these groups, they showed that the nights were after a full moon when people slept the least and went to bed one last time. These nights also had more light the night sky after dusk when the washing moon becomes brighter.
“We assume that the patterns we observed are an innate adaptation that enabled our ancestors to take advantage of this natural source of evening light that occurred at a specific time during the lunar cycle,” said author Leandro Casiraghi , a postdoctoral researcher from the University of Washington in the biology department.
Menstrual and lunar cycles
Scientists find that sleep cycles are not the only human function affected by the moon. This is not a new idea. In fact, people have long suggested that there is a connection between lunar and menstrual cycles, and some myths even suggest that fertility and lunar cycles have some kind of connection, a controversial story.
In a separate study, which was also published today in Science Advances, researchers have shown that while all the myths surrounding this connection may not hold, there may be a connection between menstrual cycles and lunar cycles.
By analyzing the records of the menstrual cycle held by 22 women up to 32 years. They examined long-term data on the onset of the menstrual cycle with data averaging 15 years in length, including information from women under and over 35. They compared these data with fluctuations in the lunar cycles to see how the two were drawn up.
They found that some of the women who participated showed those whose menstrual cycles lasted longer than 27 days “occasionally synchronized with cycles that affect the intensity of the moonlight”. according to a statement. The team found that this synchronization was slowly lost over time as the participants got older, and found that the link was reduced with increased exposure to artificial light.
More specifically, they conclude that ‘menstrual cycles are also aligned with the tropical month (the 27.32 days it takes the moon to move twice through the same equator) 13.1% of the time in women 35 years and younger and 17.7% of the time in women older than 35, indicating that menstruation is also affected by shifts in the moon’s gravimetric forces, “according to the statement.
Email Chelsea Gohd at [email protected] or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.