The idea that the full moon drives unusual human behavior — sometimes called the "lunar effect" — has been tested extensively in peer-reviewed research. A landmark 1986 meta-analysis covering approximately 100 studies concluded there is no causal relationship between lunar phases and human behavior. Subsequent large-scale studies on emergency room admissions and psychiatric hospitalizations have consistently returned null results, including a 2011 NIH-cited study finding no link between full moons and increased ER visits.
Some narrower studies have reported small correlations — for example, modest sleep disruption around the full moon in certain individuals — but these findings are inconsistent, not reliably replicated at scale, and fall far short of establishing causation. A review published on PMC (NIH) concluded that most lunar-health associations dissolve under rigorous methodological scrutiny, with surviving signals too small to support sweeping causal claims.
The persistence of the lunar effect belief is largely explained by cognitive bias: the full moon is visually salient, so people notice and remember events that coincide with it while forgetting the many uneventful full moons. Medical News Today notes this is reinforced by confirmation bias among both the public and some healthcare workers. The scientific consensus, drawn from meta-analyses and high-quality epidemiological data, is that the lunar effect on human behavior is a myth.