Moon and menstrual cycle connection: Myth or science?

Menstrual cycle, a natural monthly biological occurrence in women, has long been connected with various superstitions, religious practices and beliefs. Many people across different civilisations have also believed that a woman’s menstrual cycle has a mysterious connection to the moon. The idea isn’t entirely surprising as both follow a similar rhythm. The average menstrual cycle lasts about 28 to 29.5 days, while a lunar month spans roughly 29.5 days. But is this similarity enough to assume a real connection between menstruation and the moon? What do the latest studies say?

What science says
A recent study published in the reputed journal 'Science Advances' has revisited this intriguing question. The research suggests that the onset of menstruation in women with cycles longer than 27 days may show a slight correlation with the moon’s cyclical rhythm and with high tides. However, the report also highlights that this connection weakens as women are increasingly exposed to artificial light or as they age. For those whose menstrual cycles are shorter than 27 days, no significant link with lunar phases has been observed. "Fertility decreases with age, as does synchronisation with the moon. Menstrual cycle shortens with age, and it also shortens with exposure to artificial light at night," as per the study. 

What influences the menstrual rhythm
The study looked into 176 menstrual records over periods of 2 to 37 years, which means 6 years, from those who don't use oral contraceptives. The study also cautions against using the moon as a guide for conception planning in humans. They emphasise that a woman’s menstrual rhythm is influenced by more complex biological systems such as the hormonal, circadian and endocrine functions.