Lunar Cyclic Behavior?

[General Trelane (Retired)]

The Skeptic's Dictionary does a pretty good job of debunking this tripe.

My experience in customer service roles have shown me that people are in fact crazier than usual during a full moon.

Even when I haven't previously noted it as being a full moon, so there's that lack of expectation thing in my case.

It's called confirmation bias and selective memory, and it's why anecdotal evidence is scientifically useless. I await your controlled study to confirm that there in fact is a correlation worthy of discussion.

Well the orbit of the moon affects the sea's tides and if it can affect water, it can also affect humans, when they mostly made out of the stuff.

[and later]

. . .I am no longer going to press such a silly theory forward.

Good for you. But to build on previous rebuttals, I'll point out one more thing.

If the moon's mechanism for affecting behaviour is its tidal force, then since this force varies inversely with the square of the distance, it would be a maximum at perigee (moon closest approach to Earth). Note that the sidereal lunar period (time from perigee to perigee) is 27.5 days whereas the synodic lunar period (time from full moon to full moon) is 29.53 days (they're not the same length because the Earth moves, which means that the moon has a little further to go than one complete orbit to reach the next full moon). So perigee can occur during any phase of the synodic period. Why then would there be a correlation to a 29.5-day full-moon cycle instead of a 27.5-day orbital cycle?

Yes, we can and do get higher tides at full moons; this is because at full moon, the sun, Earth, and moon are in line, so it gets a small boost from the sun's tidal force. But the moon is opposite the Earth from the sun at a full moon, so the boost is even larger during a new moon when it's on the same side, yet nobody ever suggests that crazy behaviour is linked to the new moon! In fact, the strongest tides occur on a new moon at perigee.

I've heard people spouting the theory that the 28-day moon cycle corresponds roughly to the 28-day menstrual cycle, and thus percieved behavioral changes might somehow relate to primal urges for procreation.

Mind you, I take such claims with a grain of salt. . .

But the synodic lunar period is 29.53 days. And women don't menstrate in unison. So a huge grain of salt is required indeed! Yet it has earned certain authors a lot of money.