Myth debunked: Full moon does not increase incidence of psychological problems

Details on the study can be found on the website of the scientific journal General Hospital Psychiatry.

To determine whether the widespread belief linking the moon to mental health problems was true, researchers evaluated patients who visited emergency rooms at Montreal's Sacré-Coeur Hospital and Hôtel-Dieu de Lévis between March 2005 and April 2008. They focused specifically on 771 individuals who showed up at the emergency room with chest pains for which no medical cause could be determined. Psychological evaluations revealed that a sizeable number of these patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

Using lunar calendars, the researchers determined the moon phase in which each of these visits occurred. The results of their analyses revealed no link between the incidence of psychological problems and the four lunar phases. There was one exception, however; anxiety disorders were 32% less frequent during the last lunar quarter. "This may be coincidental or due to factors we did not take into account," suggested Geneviève Belleville. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

This study's conclusions run contrary to what many believe, including 80% of nurses and 64% of doctors who are convinced that the lunar cycle affects patients' mental health. "We hope our results will encourage health professionals to put that idea to rest," said Dr. Belleville. "Otherwise, this misperception could, on the one hand, color their judgment during the full moon phase; or, on the other hand, make them less attentive to psychological problems that surface during the remainder of the month."

In addition to Geneviève Belleville, the study was coauthored by Guillaume Foldes-Busque, Mélanie Dixon, Évelyne Marquis-Pelletier, and Sarah Barbeau from Université Laval's School of Psychology; Julien Poitras and Richard Fleet from Université Laval's Faculty of Medicine; Jean-Marc Chauny and Jean Diodati from Université de Montréal; and André Marchand from UQAM.