“The full moon causes unusual behavior in people”

The notion that the full moon triggers unusual or erratic human behavior is a deeply ingrained cultural belief with roots stretching back to antiquity. The very word "lunacy" and "lunatic" derive from "luna," the Latin word for moon, reflecting ancient associations between lunar phases and mental instability. Historical texts, like those from ancient Greece and Rome, including writings by Hippocrates and Pliny the Elder, suggested that the brain, being a "moist" organ, was susceptible to the moon's influence, much like the tides. This idea persisted through the Middle Ages and into later centuries, with some legal and medical professionals even attributing madness to lunar cycles.

Despite the enduring popularity of this myth, extensive scientific research has consistently debunked any direct correlation between the full moon and human behavior. Numerous studies examining data on crime rates, hospital admissions, accidents, and mental health episodes have found no significant statistical link to lunar phases. For instance, a 1986 meta-analysis of around 100 studies concluded there was "no causal relationship between lunar phenomena and human behavior," often identifying statistical flaws in papers claiming to find such a link. More recent studies, including one analyzing nearly 18,000 individuals treated at psychiatric wards over a decade, similarly found no evidence that the moon influences mental well-being.

The persistence of this belief can largely be attributed to cognitive biases, particularly "illusory correlation." People tend to notice and remember unusual events that happen during a full moon, while uneventful full moons are quickly forgotten. This selective memory reinforces the perceived connection, even when objective data shows otherwise. Furthermore, anecdotal evidence from professions like teaching, nursing, or law enforcement, where people often share stories of "crazy shifts" during a full moon, contributes to the myth's longevity, despite scientific evidence to the contrary.