Lunar beliefs could be
dangerous to your health

If you felt a little more agitated or anxious this past week, could it have been because the moon was full?

Traditionally people have believed that the lunar cycle affects human moods and behavior. The word, "lunatic" means literally, "moonstruck," and unusual behaviors are reported anecdotally from police, hospital emergency rooms, care homes, bartenders, retail clerks and waiters.

Misbeliefs such as these can be dangerous as they may adversely affect the way mental health workers respond to patients or the way police officers react to criminal activity.

The moonstruck phenomenon has been studied "scientifically." The conclusions have been contrasting, confusing, or misleading, often because of bad science supported by the magical and authoritative power of statistics.

"Scientific" studies began with Miami psychiatrist Arnold Lieber's 1978 book "The Lunar Effect" in which he tracked homicides in Miami and Cleveland and found that rates were higher around the full and new moons. He suggested that the moon influenced behavior through a tidal pull on the water within the human body.

Unfortunately, Lieber didn't know much about statistics, or tides.

Since the human body is about 90 percent water, it might seem like good logic to assume that it would be affected by the moon in the same way as the oceans, but the law of gravitation does not agree.

A mother holding her child exerts 12 million times as much tidal force as the moon, so it would be just as reasonable to conclude that cuddling mothers cause lunacy.

Various scientific studies have since revealed statistical correlations between the full moon and various human behaviors and moods, including psychotic and criminal behavior, depression and unruly behavior in nursing home residents, absenteeism and irregular behavior in the work place, drug and alcohol abuse, and traffic accidents.

Mark Twain expressed his disdain for statistics when he said there are "lies, damn lies, and statistics." A colleague of mine at Utah State University counters that it is a whole lot easier to lie without statistics than to lie with them, to which I add, "easier maybe, but probably not as effective."

Statistics are useful, but we must use them properly and understand what we can and cannot infer from them if they are to lead to valid conclusions.

We must also understand that statistical correlation does not necessarily imply any kind of relationship at all between the things that are being compared or analyzed.

Many of the misuses of statistics are problems that involve correlation as opposed to causality: Just because two things are related does not mean that one causes the other, especially with human behavior involving moods that can be influenced by any number of environmental, dietary, or physiological factors.

Belief systems play an even more significant role. The ancient Egyptians attributed the yearly flooding of the Nile to the appearance of the star Sirius on the horizon just after sunset because every year soon after Sirius appeared the nourishing floods would follow.

Statistically there is a one-to-one correlation, but Sirius does not cause the flooding any more than it "causes" Labor Day.

The judicious and correct use of statistics is but one of many criteria by which a study might be considered to have scientific validity, and there are many studies that are neither correct nor judicious.

The misconceptions about the moon's role in lunacy are due to a particular cognitive phenomenon called "confirmation bias," where we notice the hits and ignore the misses in support of our beliefs.

All human brains function cognitively the same way at some fundamental level, such as with the universal ability to learn language. It is deeply rooted in our psyche and it is often transparent to us, even to scientists using statistics. It is the way we learn and it is the primary adaptive tool.

It is not news when nothing happens and the media does not report "nothing happened today" when the moon is full. But if we notice "crazy behavior" when the moon is full, we tend to remember it. We may selectively remember the full moon nights when something unusual or memorable happened, or we may remember a night under the full moon when we felt particularly romantic or youthfully egregious. Because the full moon is more noticeable than no moon, we are less likely remember the many more non-full moon nights when we witnessed unusual behavior or felt a certain mood.

We likewise forget the many more numerous and uneventful full moon nights when we did not see anything unusual.

A 1996 study, "The Moon was Full and Nothing Happened," analyzed more than 100 previous studies on lunar effects. It concluded that none showed reliable, justifiable and significant statistical correlations (i.e., due to more than chance) with any phase of the moon, full or otherwise.

The report lists numerous topics that folk wisdom, anecdotal evidence and supposedly scientific studies had previously claimed were associated with the moon's cycle, including homicide rate, traffic accidents, crisis calls to police or fire stations, domestic violence, births, fertility, suicide, major disasters, casino payout rates, assassinations, kidnappings, aggression by professional hockey players, violence in prisons, psychiatric admissions, agitated behavior by nursing home residents, assaults, gunshot wounds, stabbings, emergency room admissions, behavioral outbursts of psychologically challenged rural adults, lycanthropy (becoming a wolf), vampirism, alcoholism, sleep walking, and epileptic seizure.

All of those lunacy studies contained serious flaws as scientific studies, mostly from the misuse of statistics due to confirmation bias. The errors were made because the scientists were human, not because they were charlatans, although the ranks of science, like all of humanity, contains its fair share of the latter.

As scientists we search for truth, with certain restrictions that we insist on precisely because we are human and it is too easy to convince ourselves that we have found it. As humans, we often continue to believe what we want to believe regardless of the evidence to the contrary.