Scientific studies on the effect of the lunar cycle on humans are inconclusive. Some studies showed measurable effects others have shown none. There are certainly animals that depend on the tides that are affected by the moon but any affect on people is probably slight. I know doctors and nurses who swear that there are more births during the full moon and law enforcement who swear that there is more crime during full moons. Of course, since there is an expectation of an affect it could influence behavior and expectation bias could explain perceived affects even if there are none.
I think it's a load of crap like horoscopes and astrology.