Does Crime Increase During a Full Moon?

The full moon over Manhattan viewed from New Jersey.
By Richard Dahl on August 14, 2019 2:05 PM

If tradition counts for anything, you might want to stay home behind locked doors on the night of Thursday, Aug. 15.

But that’s a big if.

Thursday, Aug. 15, is the date of the next full moon in the U.S. and Europe — and you’ve no doubt heard that full moons are responsible for an escalation of looney behavior, including an increase in crime. After all, there’s no shortage of evidence that police and emergency-medical personnel consider full moons to be their busiest times.

Is There a Connection? Well…

But that’s the trouble. The widely held belief by these public servants is apparently based largely on what they think is true. When the relationship between lunar phases and crime is more scientifically examined, a different story emerges: No connection exists. Or at least not much of one.

  • Crosstown, a nonprofit news organization in Los Angeles, has been monitoring the correlation between crime and full moons in that city since the beginning of 2018 and has found that “crime does not necessarily rise when the full moon does.”
  • Last year, the Richmond Times-Dispatch newspaper conducted a similar examination in that Virginia city over a year and found there was only a minor uptick on full-moon nights.
  • A 2010 study by Roger Williams University examined the lunar-crime relationship in San Antonio over five years and found that “the moon’s phase was not related with the level of crime and disorder reported to the police.”
  • A Mayo Clinic study in 2005 found “no association between the full moon and increased patient contacts” in the clinic’s psychiatric emergency department over a four-year period.
  • While dated, a 1985 examination of lunar-influenced crime and other behaviors, provides the most extensive review, looking at 37 other studies on the topic and concluding that “phases of the moon accounted for no more than 1% of the variance in activities usually termed lunacy.”

And Yet, Many People Are Unconvinced

In his 2003 book, “Sync: The Emerging Science of Spontaneous Order,” Cornell University professor Steven Strogatz includes a segment about the “spooky effects (that) have been ascribed to phases of the moon,” and argues that the correlations “always evaporate” upon closer examination. “Yet, many sensible people” — presumably including police and emergency-room staff — “continue to believe otherwise.”

If the evidence linking lunar phases to human behavior is so meager, why do so many people believe it exists? It might be what psychologists call “confirmation bias” — meaning that people are more likely remember things when they fit with what they believe.

So if you believe that the moon changes people and you witness a crime during the full moon on Thursday night, you’ll have something like proof and you can ignore the research.

And, if you're lucky, you might see a werewolf.

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