Does Crime Increase During a Full Moon? The Science Says No

Ask any veteran police officer or ER nurse about full moons, and you'll likely hear the same story: things get weird when the moon is full. Assaults spike, emergency calls flood in, and chaos seems to reign. It's such a widespread belief that many departments brace for impact when the lunar calendar rolls around. There's just one problem—science can't find any evidence it's actually happening.

What the Research Actually Shows

Scientists have been testing the full moon-crime connection for decades, and the results are remarkably consistent: there's nothing there. A massive 1985 meta-analysis examined 37 separate studies on lunar effects and found that moon phases accounted for less than 1% of the variance in behaviors typically labeled as "lunacy." That's statistician-speak for "basically nothing."

More recent studies have reinforced this conclusion. A 2010 analysis of five years of San Antonio crime data found zero relationship between lunar phases and reported crime. In Los Angeles, researchers who tracked the correlation between full moons and crime starting in 2018 reached the same conclusion: crime does not rise when the full moon does. A German study examined over 23,000 aggravated assaults between 1999 and 2005 and found no lunar correlation whatsoever.

The Murder Exception That Isn't

The claim gets even more specific sometimes: murder is supposedly the only crime that doesn't increase during full moons. But this doesn't hold up either. Studies looking specifically at homicide rates have found no lunar pattern. In fact, one frequently cited correlation between moon phases and Miami-Dade County homicides was later debunked when statisticians discovered the original researchers had used flawed methodology.

So Why Do People Believe It?

The persistence of this myth despite overwhelming evidence is a textbook case of confirmation bias. When something unusual happens during a full moon, we notice and remember it. When a full moon passes uneventfully, we forget. When crime spikes on a regular Tuesday, we don't connect it to anything cosmic.

Police officers and emergency workers are especially susceptible because they're primed to expect chaos during full moons. That expectation colors their perception of events. A busy night during a full moon becomes evidence of the lunar effect; a busy night on any other phase gets chalked up to random chance.

The One Real Connection

There is one grain of truth buried in the legend, though it has nothing to do with gravitational pull or mystical influence. A 2016 study found that outdoor crime—specifically outdoor crime—increased slightly with brighter moonlight. The reason? Visibility. Criminals can see what they're doing better when there's more natural light. Indoor crime showed no correlation whatsoever.

So the next time someone insists that full moons bring out the worst in humanity, you can set them straight: it's one of the most thoroughly researched and consistently debunked myths in behavioral science. The moon may light up the night sky, but it doesn't unlock some hidden criminal instinct in the human brain. That's just our pattern-seeking minds playing tricks on us.