The Short Version
The claim that full moons cause increased unusual human behavior is not supported by scientific evidence. Multiple large-scale studies, meta-analyses, and medical reviews consistently find no meaningful increase in ER visits, psychiatric admissions, crime, or other "unusual events" during full moons. While some isolated studies report small correlations with specific subgroups (e.g., sleep disruption or certain psychiatric conditions), these findings are inconsistent, not replicated at scale, and do not establish causation. This is a persistent cultural myth contradicted by the weight of research.