Full Moons and Helicopter Emergency Medical Services (HEMS) Activations in The United States

A long-standing misconception in emergency medicine is that full moons are associated with increased patient volume. Although there has been ample work debunking this belief, virtually no scholarship has tackled this question from the perspective of helicopter emergency medical services (HEMS). We examined a national-level database populated by EMS agencies throughout the United States (NEMSIS) and compared three-day periods containing every full moon in 2019 with control three-day periods one week immediately before and one week immediately after a given full moon. The daily average number of HEMS activations was then compared. A significant increase was defined as full moon periods having at least 20% more HEMS activations than the control periods before and after the full moon. In 2019, full moons had a daily average of 496 HEMS activations, and non-full moon periods had a daily average of 510 HEMS activations. Furthermore, no months saw full moons having a significant increase in HEMS activations. Our data provides important support for the idea that full moons do not translate into increased HEMS activations.