Studies of full moon effects
Here are some of the reputable studies in peer-reviewed journals that have failed to find connections:
EPILEPSY: A study in the journal Epilepsy & Behavior in 2004 found no connection between epileptic seizures and the full moon, even though some patients believe their seizures to be trigged by the full moon. The researchers noted that epileptic seizures were once blamed on witchcraft and possession by demons, contributing to a longstanding human propensity to find mythical rather than medical explanations.
PSYCHIATRIC VISITS: A 2005 study by Mayo Clinic researchers, reported in the journal Psychiatric Services, looked at how many patients checked into a psychiatric emergency department between 6 p.m. and 6 a.m. over several years. They found no statistical difference in the number of visits on the three nights surrounding full moons vs. other nights.
EMERGENCY ROOM VISITS: Researchers examined 150,999 records of emergency room visits to a suburban hospital. Their study, reported in American Journal of Emergency Medicine in 1996, found no difference at full moon vs. other nights.
SURGERY OUTCOMES: Do doctors and nurses mess up more during the full moon? Not according to a study in the October 2009 issue of the journal Anesthesiology. In fact, researchers found the risks are the same no matter what day of the week or time of the month you schedule your coronary artery bypass graft surgery.
Not all studies dismiss lunar influence.
PET INJURIES: In studying 11,940 cases at the Colorado State University Veterinary Medical Center, researchers found the risk of emergency room visits to be 23 percent higher for cats and 28 percent higher for dogs on days surrounding full moons. It could be people tend to take pets out more during the full moon, raising the odds of an injury, or perhaps something else is at work — the study did not determine a cause.
MENSTRUATION: This is one of those topics on which you will find much speculation (some of it firm and convincing-sounding) and little evidence. The idea is that the moon is full every month and women menstruate monthly. Here's the thing: Women's menstrual cycles actually vary in length and timing — in some cases greatly — with the average being about every 28 days, while the lunar cycle is quite set at 29.5 days. Still, there is one study (of just 312 women), by Winnifred B. Cutler in 1980, published in the American Journal of Obstetrics & Gynecology, that claims a connection. Cutler found 40 percent of participants had the onset of menstruation within two weeks of the full moon (which means 60 percent didn't). If anyone can tell me how this oft-cited study proves anything, I'm all ears. Also, one should be skeptical that in the intervening 29 years, nobody seems to have produced a study supporting Cutler's claim.
ANIMALS GONE WILD: A pair of conflicting studies in the British Medical Journal in 2001 leaves room for further research. In one of the studies, animal bites were found to have sent twice as many British people to the emergency room during full moons compared with other days. But in the other study, in Australia, dogs were found to bite people with similar frequency on any night.
SLEEP DEPRIVATION: In the Journal of Affective Disorders in 1999, researchers suggested that before modern lighting, "the moon was a significant source of nocturnal illumination that affected [the] sleep–wake cycle, tending to cause sleep deprivation around the time of full moon." They speculated that "this partial sleep deprivation would have been sufficient to induce mania/hypomania in susceptible bipolar patients and seizures in patients with seizure disorders." Best I can discern, however, these oft-cited suggestions have never been tested or verified with any numbers or rigorous study of any kind.
Myths persist
If one presumes that modern lighting and mini-blinds have pretty much eliminated the one plausible source of human-related moon madness, why do so many myths persist?
Several researchers point out one likely answer: When strange things happen at full moon, people notice the "coincidental" big bright orb in the sky and wonder. When strange things happen during the rest of the month, well, they're just considered strange, and people don't tie them to celestial events.
"If police and doctors are expecting that full moon nights will be more hectic, they may interpret an ordinary night's traumas and crises as more extreme than usual," explains our Bad Science Columnist Benjamin Radford. "Our expectations influence our perceptions, and we look for evidence that confirms our beliefs."
And that leads to this final note, which is perhaps the biggest logical nail in the coffin of the moon madness myths:
The highest tides occur not just at full moon but also at new moon, when the moon is between Earth and the sun (and we cannot see the moon) and our planet feels the combined gravitational effect of these two objects. Yet nobody ever claims any funny stuff related to the new moon (except for the fact that there is more beach pollution at full and new moon ...).
