However water goes down the Antipodean plughole in the opposite direction to here in Europe. That is caused by the Earth's rotation - just as cyclones and anticyclones rotate in opposite directions. In this case the macro matches the micro - but not with the gravitational pull of the moon.

If you really wanted to look for a potential factor it would be cosmic particles. They are passing right through us all day and all night, passing through the latticework of atoms like tennis balls thrown through scaffolding. They do, very occasionally, hit the structure.

We know roughly how often they hit Earth (and thus us), but we don't know exactly where they come from. There are lots of sources. All active stellar bodies emit them. But trackng any particular cosmic particle back to its source is impossible AFAIK.

You can't be me, I'm taken

Tides -> oceans -> gravity-> people's moods seems to be based on Argument by Similarity - the idea that just because two things look similar, they must be connected in some deep way.  

But how does being made of water change anything? The tides go up and down. They don't have moods or personalities. They're completely predictable and mechanical.

So where do changes in mood and behaviour come from?

The only connection is a poetic one - moods ebb and flow, the sea ebbs and flows (even though tides are mechanical), so therefore, an obvious link.

But isn't this just taking a metaphor literally?

Being made of water doesn't really make anyone moody, surely?

Do unemotional people have less water in their bodies than moody people?

Not in that sense, anyway.

(I'm not sure levity is either, but the jury is still out on that one.)

With all of these things you have to be sure there's a What before you start asking about the How. Acupuncture built up a fairly solid body of evidence for itself over a long time, and eventually the medical profession grudgingly started to take it seriously.

With something like moon lore, there are two problems. The first is that if you look at crime records, hospital admission records and other hard data there doesn't seem to be any real effect. This could be because studies have asked the wrong questions, but the current state of what's known isn't encouraging.

But assuming there's a real effect - my problem with a statement like 'It words on the tides, so of course it works on humans' is that it's a pseudo-how.

It's fine for people who want to believe it, but if you accept it it closes down further curiosity.

Once you believe you know what's happening, you lose interest in anything that might challenge that - and might also deepen your understanding beyond the usual received explanations.