Lunacy

The last couple of nights have featured a pretty dramatic full moon, and perhaps not entirely coincientally, Scientific American has a story up about an old chestnut, the so-called "lunar lunacy effect," the belief that the full moon has some kind of effect--usually a bad one--on human behavior.

One survey revealed that 45 percent of college students believe moonstruck humans are prone to unusual behaviors, and other surveys suggest that mental health professionals may be still more likely than laypeople to hold this conviction. In 2007 several police departments in the U.K. even added officers on full-moon nights in an effort to cope with presumed higher crime rates.

There have been serious attempts to study whether such a phenomenon exists, and actual evidence in support of the effect has not been forthcoming:

Florida International University psychologist James Rotton, Colorado State University astronomer Roger Culver and University of Saskatchewan psychologist Ivan W. Kelly have searched far and wide for any consistent behavioral effects of the full moon. In all cases, they have come up empty-handed. By combining the results of multiple studies and treating them as though they were one huge study—a statistical procedure called meta-analysis—they have found that full moons are entirely unrelated to a host of events, including crimes, suicides, psychiatric problems and crisis center calls. In their 1985 review of 37 studies entitled “Much Ado about the Full Moon,” which appeared in one of psychology’s premier journals, Psychological Bulletin, Rotton and Kelly humorously bid adieu to the full-moon effect and concluded that further research on it was unnecessary.

I guess the first question that always struck me when the lunar lunacy theory came up is, what would be the mechanism for it? That is, how can the moon affect behavior? Apparently, there have been attempts to ascribe the phenomenon to tidal forces, since the human body is mostly composed of water, but

First, the gravitational effects of the moon are far too minuscule to generate any meaningful effects on brain activity, let alone behavior. As the late astronomer George Abell of the University of California, Los Angeles, noted, a mosquito sitting on our arm exerts a more powerful gravitational pull on us than the moon does. Yet to the best of our knowledge, there have been no reports of a “mosquito lunacy effect.” Second, the moon’s gravitational force affects only open bodies of water, such as oceans and lakes, but not contained sources of water, such as the human brain. Third, the gravitational effect of the moon is just as potent during new moons—when the moon is invisible to us—as it is during full moons.

I read some time ago (can't remember where) that this theory may have originated in the very real phenemenon that, back before there were streetlights, on nights when the moon was full you had more people out at night, and more opportunities for mischief. The SciAm article also suggests one other source of the myth:

before the advent of outdoor lighting in modern times, the bright light of the full moon deprived people who were living outside—including many who had severe mental disorders—of sleep. Because sleep deprivation often triggers erratic behavior in people with certain psychological conditions, such as bipolar disorder (formerly called manic depression), the full moon may have been linked to a heightened rate of bizarre behaviors in long-bygone eras.

I don't know; that does seem like a bit of a reach. Anyway, I have to go turn into a werewolf now...