New study identifies potential link between Moon's phases and menstrual cycle

The association between human menstrual cycle and lunar phases goes back several centuries. While a definitive scientific link between the two was missing, a recent study has indicated that the menstrual cycle rhythms are regulated by the body's internal clock. But at the same time, there is a subtle association with the lunar orbital period.

The French and American researchers analysed data from nearly 27,000 menstrual cycles of over 3,000 women across Europe and North America. They discovered patterns referred to as "phase jumps", the way in which the menstrual phases can adjust to align with the body's internal clock.

"If the cycle lengthens, for any reason, this clock-based process adapts to quickly shorten it," neuroscientist Claude Gronfier, from The University of Lyon in France, told BBC Science Focus.

Add WION as a Preferred Source

What does it mean?

It simply means that if the Moon did have any role in the length of human menstrual cycles, it would be more of a backseat driver with the body's own internal clock firmly at the wheel, the new study, reported in the Science Alert, suggests.

The human body's circadian rhythm, with a period slightly over 24 hours, remains stable regardless of external factors like sunlight exposure. However, disruptions such as jetlag can cause this rhythm to drift out of sync.

The study notably identified a weak yet statistically significant relationship between menstrual and lunar cycles, varying by geographical location.

For instance, menstrual cycles in Europe often began during the waxing crescent phase, whereas in North America, they tended to coincide with the full moon.

Also watch |Menstruation: Study maps brain changes during periods

This is also because of the geographical difference in lifestyle variances, such as sleep-wake cycles, between populations on different continents.

The study, published in Science Advances, suggests that understanding how genes regulate the menstrual cycle's chronobiology could pave the way for novel approaches to treating ovulation disorders. However, the researchers acknowledge the need for larger-scale studies to confirm these findings and explore their clinical applications fully.

What is the bottom line?

The study does not produce anything conclusive about Moon's role in determining the human menstrual cycle. But statistically, there is a link between geography as well as the body's internal clock in governing menstrual rhythm.

(With inputs from agencies)