Mandell said the full moon myth isn't the only superstition pervading hospitals — he found that 78 percent of the nurses in his study believed that people with red hair were more prone to bleeding.
"Interestingly, when we asked if they considered themselves to be superstitious, only 23 percent said yes, showing that these tales have become such an ingrained part of the culture they take it as fact and common knowledge. As long as it doesn't get in the way of medical care, if it's what we need to get through the unpredictability of the job, then so be it. There's something comforting about believing in these things, even if you know that you are kidding yourself."
Rotton and others have spent years taking critical looks at other studies that claim to link the full moon to human affairs.
In 1985, Rotton and Canadian psychologist Ivan Kelly did a widely cited and extensive meta-analysis of 37 lunar effect studies and found that lunar cycles account for less than 1 percent of the variance in human activities. In 1992, according to the Canadian Medical Association Journal, two scientists reviewed 12 prominent studies conducted over 20 years that compared the number of crisis calls to the phases of the moon, and found that there was no correlation between the full moon and the frequency of calls reporting disturbing behavior.
The demystification of full moon myths has been a long time coming.
In the 16th century, the Swiss physician, astrologer and occultist Paracelsus wrote that "mania has the following symptoms: frantic behavior, unreasonableness, constant restlessness and mischievousness.
"Some patients suffer from it depending on the phases of the moon," according to University of Toronto psychiatry professors Alina Iosif and Bruce Ballon. In the 18th century, English legal philosopher Lord Blackstone defined the condition of lunacy as "one who hath lucid intervals, sometimes enjoying his senses and sometimes not … frequently depending upon the changes of the moon."
But there may be a simpler explanation for moon-induced behavior: moonlight. In an article on the persistence of beliefs in the lunar effect, Ballon and Iosif explain that the historic persistence of the belief has followed a relatively logical if unscientific path into the present day.
"The association between lunar phases and human behavior occupies us less today than in the past," they write. "One obvious explanation is that, before the advent of gas lighting at the beginning of the 19th century, the light of the moon permitted outdoor activities that were otherwise impossible. Full moon nights are 12 times brighter [under a clear sky] than at first or last quarter, and therefore it is likely that people stayed up later and slept less than the rest of the time. Even partial sleep deprivation can cause mania, and it is plausible that sleep disturbance during a full moon may function as positive feedback once a manic episode has begun in a predisposed person."
"Perhaps this lies at the origin of the association between madness and the full moon."