“The full moon affects human behavior and increases crime”

The idea that the full moon stirs up erratic human behavior, including an increase in crime, has roots in ancient beliefs. The very word "lunatic" derives from "luna," the Latin word for moon, reflecting historical associations between lunar cycles and changes in mental state. Ancient Greek and Roman scholars, like Aristotle, even theorized that the brain, being largely water, would be affected by the moon's gravitational pull much like ocean tides. Before the widespread use of artificial lighting, the bright full moon could have genuinely disrupted sleep, potentially leading to altered behavior or exacerbating existing mental health conditions for some individuals.

However, numerous scientific investigations have consistently debunked this long-held notion. Extensive meta-analyses, combining the results of dozens of studies, have found no statistical correlation between the moon's phases and incidents like crime rates, psychiatric hospital admissions, or general human behavior. For instance, studies analyzing violent behavior in prisons or hospital admissions related to crime show no uptick during a full moon. While some older, less rigorous studies claimed a link, more robust research has often identified methodological flaws or found no significant connection, with some even suggesting a decrease in certain offenses during a full moon. The moon's gravitational force, while powerful enough to influence vast oceans, is simply too weak to affect the water within the human body in any significant behavioral way.

Despite the scientific consensus, the belief persists largely due to a psychological phenomenon called confirmation bias. People tend to notice and remember unusual events that happen to coincide with a full moon, while readily forgetting the many times a full moon passes without incident, or when strange occurrences happen during other lunar phases. This selective memory, coupled with anecdotal stories passed down through generations and reinforced in popular culture, helps keep the myth alive, even among professionals like emergency room staff or police officers who might anecdotally report busier shifts during a full moon.