"The lunar cycle seems to influence human sleep, even when one does not 'see' the moon and is not aware of the actual moon phase," says Christian Cajochen of the Psychiatric Hospital of the University of Basel. ... The data show that around the full moon, brain activity related to deep sleep dropped by 30 percent. People also took five minutes longer to fall asleep, and they slept for twenty minutes less time overall. Study participants felt as though their sleep was poorer when the moon was full, and they showed diminished levels of melatonin, a hormone known to regulate sleep and wake cycles.
This is interesting.
But remember, the phase of the moon tells you how much of the moon is lit up at night, not how much of the moon there is out there. Perhaps the idea is that when sun and moon are on opposite sides of the earth, their gravity fields are working against each other. I remember how excited I was to find out if people had coloured auras and if the position of stars affected character and does putting a used razor blade inside a pyramid shape re-sharpen the blade. Biorhythms were the rage. Many anglers swear by the sollunar tables. It's our nature to want to believe this stuff prematurely.
Bring on the documented research.