The Aggressive Behavior of Individuals with Intellectual Disabilities is Not Affected by a Full Moon: A 17-Year Study

Abstract Due to past inconsistent results of research concerned with a possible full moon effect on the behavior of individuals with intellectual disabilities, a longer-term study was conducted. Over 17 years, no relationship was found between 210 days with full moons and 12,200 incidents of aggression that were dangerous enough to require intense physical restraint. Furthermore, and contrary to such an effect, percentage of restraint-free days was not lower during the full moon. There was less aggression and restraint during weekends and some holidays with full moons. Results suggested that a stronger social versus geophysical process might be related to past positive findings of a lunar effect and that weekend and holiday periods need to be considered as potential confounding variables. Because of the negative stereotypes associated with the full moon and unusual behavior, it is imperative that studies that find this relationship be replicated.