A Full Moon Doesn’t Make Everyone Go Crazy

By Debra Kelly on Friday, March 14, 2014
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“Go out of the house to see the moon, and ’tis mere tinsel: it will not please as when its light shines upon your necessary journey.” —Ralph Waldo Emerson, Nature

In A Nutshell

From the werewolves of the Middle Ages to present-day police forces increasing their on-duty numbers, we’ve long thought that the full moon plays a significant role in the behavior of humans. But there’s no scientific data that proves any correlation between a full moon and the number of crimes committed, suicides, hospital admissions, or any other phenomena frequently associated with the full moon. Studies that appear to support the theory can often be explained away with the inclusion of other data that’s conveniently overlooked.

The Whole Bushel

We’ve long given the full moon some sort of mystical power over human behavior. It’s when werewolves were thought to turn, when women were thought to be more fertile, and when madness was everywhere. But numerous studies that have looked at a wide variety of events such as reported crime rates (of everything from murder and assault, to disturbing the peace, to suicides, crisis center calls, and even admissions to psychiatric hospitals) have found no overwhelming evidence that the full moon has anything to do with any actual change in human behavior.

The University of Washington has compiled a list of these studies. Overwhelmingly, there’s absolutely no difference between the specified event occurring on a full moon or during another phase of the moon.

There was largely no difference in the number of reported drug overdoses, traffic accidents, emergency room admissions, suicides, psychiatric hospital admissions, and violent crime rates between periods of a full moon and during other phases of the moon. Even surgical success and failure rates were examined, along with complications.

In fact, a review of 11 years of patients admitted to a psychiatric hospital showed that more were checked in during a new moon than a full moon. Similarly, psychiatric emergency room visits were at a low during full and new moons in another, 13-year study. A three-year study of epileptic seizures also revealed a lull during the full moon.

Some studies that have shown correlations between the full moon and certain events can also be debunked. Emergency room visits for cats and dogs peaked during the full moon in a study by the Colorado State University Veterinary Medical Center, but that could also be explained by more people being out longer and later with their pets during the light of a full moon. Other studies that show an increase in accidents during a full moon can often have their data changed when other factors are looked at, such as whether or not the full moon occurs on a holiday or weekend.

Interestingly, there’s more at work than just an age-old belief in werewolves and witches when it comes to why we think that the full moon has such power over us.

One suggestion, made first by an Emory University psychiatrist, says that we think it’s true because, at one point, there was a bit of truth to the myth. However, it had less to do with the forces of the moon acting on our water-filled bodies like the tides than it did with light. When natural light was all that people had to go by, the light of the full moon was a major disruption to sleep cycles. By the time people had been deprived of a good night’s sleep after the third or fourth night of a moon’s full appearance, there were a lot of cranky, moody, and overtired people. Accidents were more likely to happen, fights more likely to break out, medical and mental conditions were likely to be more pronounced not precisely because of the moon, but because it had been keeping people awake.

We may have also been seeing a difference in the behavior of the animals around, us, too; but that’s also for a very practical reason rather than any kind of lunar pull. The bright light makes nighttime journeys much more dangerous for prey animals, so they simply stay sheltered. And larger predators know this, too, so they have a tendency to be less active during the full moon.

Show Me The Proof

University of Washington: The Full Moon
LiveScience: ‘Supermoon’ Lunacy: Does the Moon Make Us Crazy?
Scientific American: Lunacy and the Full Moon