You and the Moon
There has always been a stong connection between the moon and the menstrualcycle. The moon has its own cycle, growing full from a tiny sliver, andthen shrinking back down again. A full cycle the moon (a synodic month)lasts 29 and one half days. The moon's cycle is clear, and very predictable,and it was the first way we measured a month.
Oddly - or perhaps not oddly at all - the human menstrual cycle is verysimilar to the moon's cycle. The average length of the human menstrualcycle is about 28 days, which is closer to the moon's cycle than any othermenstruating animal. Also, women think of the space between their periodsas a "month" even though it might not be a calendar month. Somewomen call their period "the monthlies".
This old association of months, moons and menstruation is even presentin our language. Menstruation comes from the Latin word "menses"which means the menstrual flow, but is also the plural form of the word"mensis" which means month. These Latin words for month probablycame from the Greek word for moon: mene. The root word "mens"is found in words having to do with measurement - like the word mensuration,which means the act of measuring. The word for the first time a girl menstruates- menarche - is made up of the Greek word for month (men) and the wordfor beginning (archie). So you can see how closely related are the ideasof measuring time, the moon and menstruation.
In different places at different times all over the world, people haveassociated the full moon with ovulation and dark of the moon with menstruation.In some places, when the moon dissapears from the sky it was said to bemenstruating. Another name for a period is "moontime." Some womenstill notice that they tend to bleed either at the full of the moon orthe dark of the moon, but not at the quarters. Legends of different culturessay that all women used to bleed together, matching their cycles to thecycle of the moon. The moon has always been associated with women. Thinkof the goddess Diana, the goddess of the moon, and the hunt.
An interesting side note to this is that experiments have shown thatwomen with irregular menstrual cycles have become more regular by sleepingwith a soft light on in their rooms (to stand in for the light of a fullmoon) during the fourteenth, fifteenth and sixteenth days of their cycle,the days they would ideally be ovulating. After a few months, their cyclesregulate. This is called the Dewan effect, and it seems to show a connectionbetween light and the menstrual cycle. Perhaps it also explains old traditionsin which women went out and talked to the moon when they were having difficultieswith their periods.