Not carried away by a moonlight shadow: No evidence for associations between suicide occurrence and lunar phase among more than 65,000 suicide cases in Austria, 1970-2006

OBJECTIVES: Belief in lunar effects on abnormal or deviant human behavior ("moon madness") is old, common, perpetuated by the media and notably widespread among health professionals, and may thus have public health consequences. This study investigated lunar effects on one particular outcome (completed suicide) for which the literature appears unsettled, owing to some recent reports with positive findings. METHODS: The timing of all 65,206 suicides (46,451 men; 18,755 women) officially registered in Austria between 1970 and 2006 was analyzed with respect to the phases of the moon. This was the first such study based on national data conducted outside the USA, with the database comprising the second-longest study period and the second-largest sample ever investigated in this subject area. RESULTS: Observed proportions of both male and female suicide occurrence did not deviate from expected proportions during the new, crescent, full, and decrescent moon quarters or from those expected for 3-day windows centered around new and full moon, relative to the interphase. Subgroup analysis (by sex and year), additionally conducted for demonstration purposes, yielded results conspicuously resembling those of related studies with positive findings; namely, sporadically emerging significant findings that were entirely absent in the overall analysis and directionally erratic, thus suggesting they were spurious (false positive). CONCLUSIONS: This large-sample evidence strongly suggests no lunar effects on the timing of completed suicide. Scattered previous evidence in support of such effects in all likelihood was spurious; that is, was due to statistical type 1 errors or erroneously taking calendrical periodicities of suicide occurrence that are real as evidence for lunar effects.