With a full moon coming early tomorrow morning, maybe you're contemplating John Fogerty's classic take on the matter, in Creedence Clearwater Revival's "Bad Moon Rising": "Don't go around tonight/Well it's bound to take your life/There's a bad moon on the rise."
Go ahead—ponder the words and hum the catchy melody, but remember that any claims about the moon's perceived influence over our affairs are, as a new analysis highlights, almost surely complete malarkey.
"The moon is innocent," writes University of California-Los Angeles astronomer Jean-Luc Margot.
Despite countless studies demonstrating full moons—or new moons, or harvest moons, or whatever moons—have no effect on psychological disorders, sleep patterns, or really anything except lunar ranging experiments, the belief persists that the shimmering silver orb visiting us roughly every 29.5 days actually has some power over us. It even persists among emergency room nurses and doctors, substantial majorities of whom believe full moons increase ER admissions, according to a 1987 study titled, appropriately, "Lunacy." Believers also include a number of scientists, who continue to publish studies claiming a connection between the moon and crime, hospital admissions, and lots of other things.
Beliefs lead to action, and flawed beliefs have real societal costs, as illustrated by recent debates over vaccines and climate change.
Margot felt he had to do something about that. So, as he details in a new paper, he picked out a study of admissions to hospitals in Barcelona that suggested admissions were higher on full moon days.
Margot noted problems with the statistical tests in the Barcelona study, variations in the length of the lunar cycle that may have biased results, and the fact that there were a number of days throughout the lunar cycle where admissions were very nearly as high as on full moon days. Margot also takes issue with the Barcelona study's speculation that the moon could influence us through tidal effects on our blood, an idea Margot politely suggests is based on "misconceptions" about how tides work.
Though the authors of the original paper dispute some of the criticisms in an accompanying back-and-forth, Margot remains steadfast and argues that persistent interest in a moon-human connection has more to do with cognitive biases—particularly confirmation bias, which leads us to more readily accept evidence supporting claims we already believe—than anything else. That echoes the conclusions of a 2014 Max Planck Institute study that suggested publication bias, an effect that discourages publishing null results or the absence of an effect, may explain the frequent claim that full moons affect sleep.
The persistence of such beliefs doesn't bode well for us, Margot argues. Beliefs, he says, lead to action, and flawed beliefs have real societal costs, as illustrated by recent debates over vaccines and climate change.
"The study illustrates how intelligent and otherwise reasonable people develop strong beliefs that are not aligned with reality. Allowing your brain to develop beliefs that are inconsistent with indisputable facts is poor brain hygiene. It's like allowing your teeth to decay," he writes on his website. And really, nobody wants that.
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