i'm not sure... i guess it is a lunar cycle (a monthly cycle) but i'm not sure about the in phase with full moon thing...

because...

women who live together tend to cycle together. i think they tend to converge on around the same time...

but everyone can't cycle with the moon or they wouldn't alter when women moved.

it is kinda interesting...

amazing how our bodies react to pheremones (i guess it is about that) lol.