Full Moons & First Responders: Fact vs. Fiction

Rather listen?
Full blog audio at the bottom.


If you’ve been on shift long enough, you’ve probably said it—or heard it—on a busy night:
“Must be a full moon.”

The idea that people act differently when the moon is full is centuries old. In fact, the word lunatic comes from Luna, the Latin word for moon.

But how much of this is real, and how much is just tradition that is passed around?

What the Science Actually Says

1. Brain Structure Changes—Yes, Really

A 2025 MRI study scanned healthy volunteers during four different lunar phases. Researchers found measurable changes in brain structures like the ventricles, hippocampus, and thalamus. The largest differences showed up between the new moon and the third quarter.

The cause is still unknown. It could be gravity, circulation, hydration status, or something else entirely.

The study was small, so we can’t draw hard conclusions. But it’s the most direct physical evidence yet that lunar cycles might influence human biology.

(Source: ResearchGate – Changes in Brain MRI Under Different Lunar Cycles)

2. Sleep Changes Are the Most Consistent Finding

Across multiple studies, people sleep differently around a full moon:

  • Less total sleep

  • Less deep (NREM) sleep

  • Longer time to fall asleep

This effect shows up even in controlled lab environments with no exposure to moonlight. That suggests there may be an internal biological rhythm tied to the lunar cycle.

Less sleep can make people more irritable, impulsive, or emotional. That could be one reason some nights feel more intense for responders.

(Sources: Cleveland Clinic, PMC7322537)

3. Behavior and Emergencies: No Consistent Spike

Large-scale reviews find no reliable link between full moons and increases in violent crime, psychiatric admissions, or ER visits.

Some small studies have noted a rise in outdoor accidents during bright moonlight. But this is likely due to better visibility and more nighttime activity, not the lunar phase itself.

(Source: Medical News Today)

Why the Myth Lives On

Station talk & stories: We remember the wild nights on a full moon. The quiet ones fade from memory.

History & language: For centuries, folklore and medicine have linked the moon to human behavior.

Expectation bias: If you expect a busy shift, every call that proves you right stands out.

What It Means for the Job

Even if the moon isn’t actually stirring things up, plenty of people end up sleeping less and feeling more on edge. If you’re heading into a full moon shift, have a couple of quick resets ready for when things get jumpy.

We’ve got a sleep reset blog with off-shift ideas you can actually use—without ditching energy drinks or overhauling your routine. Things like brown or pink noise, weighted blankets, and other ways to take the edge off so you’re not carrying the shift home.

Sources:

  • ResearchGate – Changes in Brain MRI Under Different Lunar Cycles: A Cross-Sectional Study

  • Cleveland Clinic – How the Moon Affects Humans

  • National Library of Medicine – Lunar Cycle Effects on Human Sleep

  • Medical News Today – Do Full Moons Affect Human Behavior?

 

 


Previous
Previous

Are First Responder Kids More Likely to Follow in Their Parents’ Footsteps?

Next
Next

Should Families See the Body After Traumatic Death? First Responder Perspectives.