If on Tuesday you sense a little lunacy in the air, you might not be mistaken. The full moon may not turn us into hirsute, rabid werewolves, running about on all fours, but it does make us go a little peculiar. According, that is, to a long line of anecdotal and circumstantial evidence.
The latest 'proof' came from police in Brighton, southern England, who calculated that arrests for disorder, affray, licentiousness and drunken debauchery in the seaside town rose and fell with the lunar cycle.
Simply put, a full moon is a lunar phase that occurs when the moon is at the opposite side of the Earth from the sun when the three celestial bodies are in as straight a line as possible. This happens once every 29.5 days, which is why it doesn't always happen once a month, at least in the western calendar - it does in the Hindu, Thai, Islamic, Celtic, Hebrew and Chinese calendars.
At that time, the hemisphere of the moon facing the Earth (the near side) appears perfectly round because it is fully lit by the sun. Of course, on the other side of the Earth (the far side) during this phase, there appears to be no moon because it is not illuminated at all. Lunar eclipses are only possible during full moons as the moon passes through the shadow cast by the Earth.
Brighton's cops are by no means the first to spot behavioural changes around full moons. Scholars at Germany's Turbingen University have claimed police reports show a marked increase in binge drinking around a full moon, while a three-month psychological study on 1,200 inmates at a northern English prison showed a rise in violent incidents. Then there's an American study that showed a full-moon tripling of murders and a 35 per cent rise in aggravated assaults in Toledo, Ohio.
It's not just violence. The full moon has also been aligned with a rise in casino payouts, kidnappings, traffic accidents - up 50 per cent, claimed one insurance firm recently - and sleepwalking. Epilepsy is more common too, while airline passengers are tetchier. And, how shall we put this, humans become more frisky, according to professor Michal Zimecki in Poland; fertility rates, menstruation and birth rates are affected by the lunar cycle too. Believe it or not, hamsters turn their wheels 'more dizzily' - that's faster to you and me - over the full moon.
The words 'lunacy' and 'lunatic' derive from Luna, the ancient Roman goddess of the moon - that 3,500km-wide glowing orb in the sky located some 390,000km away. So does a full moon always lead to a full loon?
No. Just because two things happen at the same time does not mean there is a cause and effect. Surgeons in Bradford, England, reported twice as many dog bites over a full moon while a study at Sydney University, Australia, found no such link.
Quite why we should go a little barmy, however, is a mystery. Pragmatists claim an Earthly reason - the light is to blame. The lighter the night, the more we go out and play, say sociologists, hence the more accidents, fights and lusty encounters. In the past, people simply partied more at full moons because they had more light, plus it signalled either the start of a new month, or the end of an old one (depending on how you look at it).
If a hamster could pop out of its cage and party, presumably it would. But it can't - all it can do is turn its hamster wheel 'more dizzily'.
Of course, the real question here is not whether the full moon makes us mad but who paid for a study on the full moon's effects on hamsters and what did they hope to gain from it?