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Does a full moon lead to erratic behavior? Scientists say 'no'

Oct 28, 2015

Throughout history, humans have often thought the full moon changes a person’s behavior – most notably through Hollywood movies about humans turning into vampires or werewolves. In fact, the word “lunatic” itself derives from the Latin word for moon, “luna.”

And as Dustin Dwyer on our State of Opportunity team points out, some teachers put full-moon days on the calendar -- preparing for squirrelly kids.

We also put the question out on social media throughout the week. We asked if people notice more temperamental kids or other peculiar behavior during a full moon, and most people tended to say "yes."

Going beyond just a social media call-out, Scientific American writes about a survey that shows how people associate the full moon with a range peculiarities, from suicides and homicides, to fights at hockey games.

One survey revealed that 45 percent of college students believe moonstruck humans are prone to unusual behaviors, and other surveys suggest that mental health professionals may be still more likely than laypeople to hold this conviction. 

In 2007, the UK went so far as to deploy more police officers on full-moon nights in preparation for higher crime rates.

In 1978, psychiatrist Arnold Lieber even authored a book, entitled How the Moon Affects You, characterizing human behavior shifts during full moons.

Like the way lunar gravity causes high tides, Lieber claimed a full moon shifted the water molecules in the human body, which is nearly 80% water.

Scientists squashed this theory, however, soon after publishing, Scientific American says. In reality, the gravitational pull a full moon exerts on the human body is the same as the pull of any other moon: close to nothing.

No evidence

Despite the frenzy around a full moon, scientists have yet to find any backing on the phenomenon.

In 1998,  a study published in The Australian and New Zealand journal of psychiatry found there to be no relationship between total violence and aggression or level of violence and aggression and phase of the moon.

And Ivan Kelly, a psychologist at the University of Saskatchewan, reviewed over 100 studies of lunar cycles and behavior, including emergency room visits and suicide attempts, and found none of these peculiarities can be explained by the full moon.

Although there is no scientific correlation between a full moon and crazy behavior, there is a reason why humans continue to believe in the urban legend.

According to Psychology Today, it is due to the fact we think the full moon should lead to more volatility – therefore, we notice something peculiar more than we would on any other day. This phenomenon is referred to as the “illusory correlation,” or the perception of an association that does not actually exist.

"We have sort of a bias for remembering and observing the things that fit with our own beliefs."

Dean Lauterbach, professor in the psychology department of Central Michigan University, says on a full moon, people tend to remember behavior or situations that were out of the ordinary more than on any other normal day.

Scientific American points to a 2005 study where nurses who believed in the “lunar lunacy” effect wrote more notes about patient problems than those who did not believe the phenomenon.

"We have sort of a bias for remembering and observing the things that fit with our own beliefs," Lauterbach says.

So if you notice your classroom acting up this week, it might be from pre-Halloween jitters or higher consumption of donuts and cider – so far, science doesn't support the idea that it's because of the "full moon effect."

- Allana Akhtar, Michigan Radio Newsroom