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The full moon doesn't make you crazy, study confirms

A nearly full moon sets over waters of Cook Inlet and a children's whale slippery slide just before sunrise on Tuesday, at Elderberry Park in downtown Anchorage, Alaska. Anchorage's next full moon is Wednesday.
A nearly full moon sets over waters of Cook Inlet and a children's whale slippery slide just before sunrise on Tuesday, at Elderberry Park in downtown Anchorage, Alaska. Anchorage's next full moon is Wednesday.Dan Joling / AP

When there's a full moon (like the one Wednesday), there's a tendency to blame some people's strange behavior on it. But a new Canadian study dismisses this popular belief and suggests that more people with psychological problems do not show up at hospital emergency rooms during a full moon.

Researchers found little evidence that the moon's lunar cycles were linked to an increased incidence of mental health concerns. 

In other words, the moon's behavior seems to have no effect on human behavior on planet Earth. Sure, the word "lunatic" derives from the Latin word "luna" for "moon," but science has found little connection between the moon and madness.

Even so, that won't stop some of us from thinking that lunar cycles can influence psychological symptoms. By one estimate, 80 percent of nurses and 64 percent of doctors who work in the emergency department believe it affects patients' mental health.

In the study, which will appear in the journal General Hospital Psychiatry, researchers reviewed medical records from two hospitals in Montreal over a three-year period. They looked at nearly 800 patients who came to the emergency room for unexplained chest pains, meaning doctors aren't sure what caused their heart trouble.

Researchers studied unexplained chest pains because people with this complaint often suffer from many psychological difficulties, including panic attacks, anxiety and mood disorders, and suicidal thoughts.

They also investigated this topic because the research team was already conducting a study on panic attacks and unexplained chest pains. And the emergency department personnel would often make comments, such as "This would be a good night for research because it's a full moon," says study researcher William Foldes-Busque, PhD, an assistant professor of psychology at the University of Quebec in Montreal, Canada. So, experimenters knew some health professionals already had this perception in their heads, but they wanted to see if the idea had any truth to it.

After patients completed a mental health evaluation, scientists then analyzed data to find out if their psychological symptoms revealed any seasonal patterns or lunar phase influence. Researchers were able to determine which one of the moon's four phases -- new moon, first quarter, full moon, or last quarter -- was present on the day each patient came to the emergency room.

The study found that lunar cycle had no influence on the occurrence of psychological problems, such as panic attacks, anxiety and mood disorders, or suicidal thoughts. The only exception was a 32% drop in the frequency of anxiety disorders during the moon's last quarter. 

"We don't know for sure why this happened," says Foldes-Busque.

Other studies have looked at admissions to psychiatric hospitals, calls to crisis hotlines, or homicide rates, and also failed to turn up a link between the moon's illumination and behavior changes. But if you talk to health professionals or police officers, they may think there's more nuttiness and craziness during a full moon. 

It's possible that people are more prone to notice -- and remember -- a full moon, so they may link any strange behaviors they see that day to it. And perhaps when people act odd during other times of the month, they're just considered weird -- no further explanations given.

Foldes-Busque says it's possible the moon affects mental health in other ways. "I've heard that the full moon may affect sleep, mostly because of increased luminosity," he says.

What's his advice for today's full moon? "Don't do anything special or change anything because of it."


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