Does a full moon make crime rates go up?

Summary

More or Less – “Does a Full Moon Make Crime Rates Go Up?”

BBC Radio 4 | Aired: July 4, 2026
Host: Lizzie McNeil
Guest: Eric Chudler, Neuroscientist, University of Washington

---

Episode Overview

This episode of More or Less investigates whether the widely held belief that crime rates spike during a full moon holds any statistical water. Host Lizzie McNeil, with expert guest Eric Chudler, delves into studies, old legends, and the science behind lunar lore—ultimately weighing myth against robust data. The discussion skillfully blends skepticism with curiosity, dissecting evidence from policing anecdotes, behavioral science, and peer-reviewed research.

---

Key Discussion Points & Insights

The Origin of the Full Moon-Crime Belief

• Inspector Andy Park (Brighton, 2007) noticed peaks in violent crime around paydays and full moons, sparking local discussion and this episode’s central question.
• The term "lunacy" itself traces back to “lunaticus,” Latin for “moonstruck”—hinting at the deep roots of lunar superstitions.

  “People have long suspected the moon of meddling with our minds. In fact, the word lunacy comes from the Latin lunaticus, meaning moonstruck.” (A, 00:37)

Gravitational Theories—Do They Hold Water?

• Chudler explains the popular notion: if the moon moves oceans (tides), might it not move us?
• Physics says no—the moon's gravitational impact is minuscule on human bodies compared to the ocean, and is unchanged during new versus full moons.

  “The gravitational pull of the sun and the moon on the Earth during a full moon is about the same as it is as a new moon... The only difference is the reflection of the sun on the moon that we see.” (B, 02:27)

What Does the Data Say?

Major Studies

• Host summarizes a major study from Brisbane, Australia (2004–2011):
  • No detectable spike in crime or mental health incidents during full moons compared to other nights.
• Of roughly 24–25 peer-reviewed studies on lunar phases and crime, only 3–4 found any positive correlation; most found none, or even a decrease.

  “In my mining of the published literature... three or four have shown a positive correlation between the full moon and any abnormal behavior. The other ones have shown no correlation at all.” (B, 03:49)

• Different studies use varying definitions of “full moon” (single day vs. several days around it) and often cover only a small number of lunar cycles—reducing statistical power.

Methodological Problems

• Many positive-correlation studies fail to control for variables like weekends, holidays, weather (cloud cover), or event nights.

• Cloudiness could affect whether the moon’s visible—mirrored humorously in references to “Harry Potter” (Remus Lupin’s transformations).

• Short study periods and inconsistent methodology undermine conclusions about causality.

  "Some studies have said... just that one day that the full moon occurs. Other studies have said, well, we’re going to take the full moon plus a few days before and a few days after... Different studies have used different ways to classify and do their statistics.” (B, 05:21)

Correlation vs. Causation

• Chudler stresses: association does not imply causation.

  “They’re correlating some abnormal behavior... to a different phase of the moon. And just because two variables vary with each other, it doesn’t mean that one variable causes the other.” (B, 06:10)

Why Does the Belief Persist?

• Much evidence is anecdotal—especially among police, nurses, emergency workers.

  • Two studies showed these professions are more likely to believe in lunar effects.

  “Social workers, emergency doctors, nurses, police officers... have the strongest beliefs that the full moon affects behavior.” (B, 06:34)

• Beliefs can trigger self-fulfilling prophecies:

  • Example: Sussex police deploying more officers during full moons led to more recorded crime—not lunar effects, but increased policing.

  “Because more police officers were put on the street looking for crime, more crime and more arrests could be made. So it’s a self-fulfilling prophecy.” (B, 07:02)

• The timing of full moons often coincides with weekends or student nights (83% in 2007 in Brighton, 75% in 2006), where social activity is naturally higher.

  “Having been a student in Brighton a few years later, I suspect discounted drinks and stag parties might have been the real culprits.” (A, 07:39)

• Confirmation bias: people notice dramatic events during a full moon, but ignore similar happenings at other times.

  “They might notice that the moon is full on a particular day when something happens in their job... but they don’t notice when these same things happen at different times of the month.” (B, 08:16)

---

Notable Quotes and Memorable Moments

• On the limits of moon’s power:

  “No tidal surges of bad behavior. Sadly.” (A, 02:02)

• On the enduring appeal of lunar lore:

  “Minor obstacles like scientific evidence have never been particularly effective at spoiling a good story.” (A, 02:49)

• On Remus Lupin and plot holes:

  “Now, some might call that a plot hole. Others, compelling evidence.” (A, 04:49)

• Closing flourish:

  “There is no compelling statistical evidence that the full moon causes crime to go up, nor is it made of cheese, but it is made of rock and heavy metal. Rock on, little moon, rock on.” (A, 08:31)

---

Important Segment Timestamps

• 00:37 – “Lunacy” and Brighton crime origins
• 01:09 – Framing the big question: Does the full moon increase crime?
• 02:27 – Explaining the moon’s gravitational pull
• 03:16 – Study: Brisbane police call data (no lunar effect)
• 03:49 – Review of overall studies (almost all negative)
• 05:21 – Problems with study time frames and definitions
• 06:10 – Correlation does not equal causation
• 06:34 – Professions most likely to believe in lunar effect
• 07:02 – Self-fulfilling prophecy & Sussex police
• 07:39 – Full moons and social calendars (weekends, student nights)
• 08:16 – Explanation of confirmation bias

---

Summary

The More or Less team thoroughly debunks the myth that full moons are linked to increased crime. Despite persistent anecdotes and cultural myths, rigorous statistical analysis shows no consistent correlation—and certainly no causal effect. The episode highlights the power of confirmation bias, self-fulfilling prophecies, and the human tendency to seek patterns in chaos. But the moon’s crime-fighting days, it seems, are pure fiction—best left to werewolves and wizards.

Transcript

[A]

Hello and thanks for downloading the More Or Less podcast. We're the programme that looks at the numbers in the news life and in the waxing and waning of crime. And I'm Lizzie McNeil. It's 2007 in Brighton, southern England, UK, a city not unfamiliar with antisocial behavior. Inspector Andy park decided to look into what factors cause crime to peak within the city. He studied violent crimes recorded over the past year and noticed that there was an uptick every time it was payday and during the full moon. Now, people have long suspected the moon of meddling with our minds. In fact, the word lunacy comes from the Latin lunaticus, meaning moonstruck. Ouch. One listener, Richard, saw references to the moon's criminal effects, but was skeptical.

[B]

It is said that crime rates go up when it's a full moon. Is there any statistical validity to this?

[A]

We all know the moon has a dark side, but is it really that dark? This week, we're finally holding the moon to account and asking, does the full moon make the crime rate go up?

[B]

Many people believe that the full moon causes changes in behavior. But just because people believe it, doesn't make it true.

[A]

That's Eric Chudler, a neuroscientist from the University of Washington who's been collecting studies on the effect of the moon on behavior for, well, many a moon.

[B]

People have thought that perhaps because the gravitational effect of the moon and the sun on our tides make changes, perhaps because the body and the brain is full of water, that's perhaps why the moon might affect our behavior.

[A]

Now, while this theory has a certain poetic charm to it, the science says otherwise. Sure, the Moon's gravitational pull is powerful enough to shift entire oceans, but when it comes to humans, the laws of physics dictate that we're simply too small for it to make any meaningful difference. No tidal surges of bad behavior. Sadly,

[B]

the gravitational pull of the sun and the moon on the Earth during a full moon is about the same as it is as a new moon. When we can't see the Moon at all, the gravitational pull is about the same. So the only difference is the reflection of the sun on the moon that we see. So why don't people. Aren't people concerned with a new moon? Why are they only concerned with a full moon?

[A]

Why indeed? Still, minor obstacles like scientific evidence have never been particularly effective at spoiling a good story. To spoil a good story, you really need social science.

[B]

There's been a number of studies over the past, say, 50 years or so where people have looked at the statistics behind the correlation between the full moon or the phase of the moon and crime.

[A]

One study from Australia analyzed the calls made to Brisbane Police between 2004 and 2011 concerning incidents of things like domestic violence, racial rape, murder, fatal traffic accidents, and mental health crises. The data showed no increase during nights of the full moon compared to non full moon nights, neither in volume nor type of incidents. In fact, the majority of studies show no correlation between a full moon and criminal activity.

[B]

In my mining of the published literature, these are in peer reviewed studies. There are about 24 or 25 studies that have looked specifically at criminal activity. And I would say that out of those 24, 25 studies, three or four have shown a positive correlation between the full moon and any abnormal behavior. The other ones have shown no correlation at all.

[A]

One study even found a decrease. But what about those three or four studies that showed a positive correlation? Were they in towns inhabited by werewolves or more lunarly sensitive folk? Alas, probably not.

[B]

We need to control for when did that full moon happen? For example, did they happen on weekends, did they happen on holidays and things like that? Also, did those studies happen on cloudy days where people could see the moon? And a lot of those variables just are not controlled in most studies.

[A]

Cloud cover arguably does matter. After all, as all Harry Potter aficionados know, Remus Lupin managed to remain perfectly human and until the moon burst through the clouds as he stepped out of the shrieking shack. Now, some might call that a plot hole. Others, compelling evidence. A more grounded explanation is that brighter nights simply make things easier to spot, including crimes. Eric also points out that some of these studies weren't exactly long running either.

[B]

Those three or four studies that have shown a positive correlation have usually used just a small number of full moon cycles, cycles like ovary year that would give you approximately 12 full moons. It's not as powerful as a study that would look over a longer period of time. Different studies have used a different criteria for what they consider to be a full moon. Some studies have said that we'll look at the statistics of just that one day that the full moon occurs. Other studies have said, well, we're going to take the full moon plus a few days before and a few days after. We're going to consider that for our data to analyze. So different studies have used different ways to classify and do their statistics.

[A]

Another problem is that these studies are not able to prove a causal link.

[B]

They're correlating two variables. They're correlating some abnormal behavior like the number of murders or the number of crisis calls. And they're correlating that to a different phase of the moon. And just because two variables vary with each other, it doesn't mean that one variable causes the other.

[A]

The belief that full moons cause spikes in crime is largely from anecdotal evidence.

[B]

Two studies that were done about 30 years or so ago looked at the different professions of people who believe in this. And what they found is that social workers, emergency doctors, nurses, police officers, they have the strongest beliefs that the full moon affects behavior.

[A]

And this brings us back to the story we mentioned at the opening of this program back in Brighton in 2007, and that uptick in crime.

[B]

One reason why I think people believe that the full moon affects behavior is a self fulfilling prophecy. In 2007, a police department in Sussex said that they had noticed that there was more crime. And so because there was going to be more crime in a full moon, the police department could put more police officers on the street. And because more police officers were put on the street looking for crime, more crime and more arrests could be made. So it's a self fulfilling prophecy, not because the full moon has some magical effect on the brain, but rather people are looking for particular behavior, so it reinforces their belief.

[A]

Now, I've looked into the dates of the full moon for 2007 and 2006. In 2007, 83% of the full moons occurred on student nights or weekends. In 2006, it was 75%. Now, having been a student in Brighton a few years later, I suspect discounted drinks and stag parties might have been the real culprits. Emergency service workers belief in the power of the moon could also be due to confirmation bias. Humans like to find patterns in chaos. Full moons often draw our attention.

[B]

They might notice that the moon is full on a particular day when something happens in their job and they assign blame to something like the full moon. But they don't notice when these same things happen at different times of the month.

[A]

So there you go. There is no compelling statistical evidence that the full moon causes crime to go up, nor is it made of cheese, but it is made of rock and heavy metal. Rock on, little moon, rock on. And that's all we have time for this week. If you have any questions or comments, please write in to more or lessbc.co.uk until next week. Goodbye.