Research Article Effects of Full-Moon Definition on Psychiatric Emergency Department Presentations Varinder S. Parmar, 1 Ewa Talikowska-Szymczak, 1 Emily Downs, 2 Peter Szymczak, 1 Erin Meiklejohn, 2 and Dianne Groll 1 1 Department of Psychiatry, Queen’s University, 752 King Street West, Kingston, ON, Canada K7L 4X3 2 Department of Psychology, Queen’s University, 99 University Avenue, Kingston, ON, Canada K7L 3N6 Correspondence should be addressed to Varinder S. Parmar; vsp908@gmail.com Received 30 October 2013; Accepted 18 December 2013; Published 12 January 2014 Academic Editors: C. Damsa and P. Eisenburger Copyright © 2014 Varinder S. Parmar et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. Te lunar cycle is believed to be related to psychiatric episodes and emergency department (ED) admissions. Tis belief is held by both mental health professionals and the general population. Previous studies analyzing the lunar efect have yielded inconsistent results. Methods. ED records from two tertiary care hospitals were used to assess the impact of three diferent defnitions of the full-moon period, commonly found in the literature. Te full-moon defnitions used in this study were 6 hours before and 6 hours afer the full moon (a 12-hour model); 12 hours before and 12 hours afer the full moon (a 24-hour model); and 24 hours before and afer the day of the full moon (a 3-day model). Results. Diferent signifcant results were found for each full-moon model. Signifcantly fewer patients with anxiety disorders presented during the 12-hour and 24-hour models; however, this was not true of the 3-day model. For the 24-hour model, signifcantly, more patients presented with a diagnosis of personality disorders. Patients also presented with more urgent triage scores during this period. In the 3-day model, no signifcant diferences were found between the full-moon presentations and the non-full-moon presentations. Conclusions. Te discrepancies in the fndings of full moon studies may relate to diferent defnitions of “full moon.” Te defnition of the “full moon” should be standardized for future research. 1. Introduction Te belief that the lunar cycle is associated with the onset and severity of psychiatric symptoms has persisted since the middle ages [1]. Tis belief still occurs in some mental health professionals, who report that the agitation of psychiatric symptoms induced by the full moon results in increased admissions, suicides, homicides, and emergency department (ED) visits [1–4]. Opinion surveys conducted with ED per- sonnel also indicate the belief that the demand for patient services increases during the full moon [4, 5]. Te belief that the lunar cycle infuences the frequency and severity of emergency psychiatric presentations is clearly widespread. However, few studies conducted to date have found consistent evidence in support of a lunar efect [1– 3, 5–13]. Te bulk of lunar research has found no relationship between lunar activity and ED psychiatric presentations [5– 10]. Tese fndings suggest that psychiatric ED presentations are not infuenced by the phases of the lunar cycle. Despite being in the minority, some retrospective studies have found a relationship between the frequency of criminal behaviour or psychiatric crises and the lunar cycle [11, 12]. Templer and Veleber found that a disproportionate number of suicide attempts, emergency and counseling telephone calls, acute psychiatric hospital admissions, arrests, and schizophrenia hospital admissions occurred during the full and new moons [11]. Other researchers have found a rela- tionship between criminal behavior and the lunar cycle. Several criminal ofences including rape, robbery and assault, burglary, property and automobile thef, drunkenness, and disorderly conduct have been found to occur more frequently 3 days prior to and following the full moon than at other times Hindawi Publishing Corporation ISRN Emergency Medicine Volume 2014, Article ID 398791, 6 pages http://dx.doi.org/10.1155/2014/398791