This is true what arches said about the moon. I do this.
I haven't had a period since 19 as I had a hysterectomy but still have PCOS so
I have to rely on the moon for my cycle.
Its good to sleep on the 13, 14, and 15 night of the luna calendar with your curtains open to get the rays of the moon. Your cycle will regulate like the tides of the ocean.
I regularly fast on these days especially too.
I also wax on the 13th luna day as the hair grows back slower lol. You can cut your hair according to the moon too.