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Name: Cecilia
Status: student
Grade: 6-8
Location:  TX
Country: N/A
Date: January 2007

Why do people act crazy on a full moon?

They don't! Or not any more than usual. That is a legend or myth that has persisted for a long time, but there is no evidence that it is true. A scientist or any critical thinker will always look for supportable evidence before accepting any statement. Thanks for asking.

J. Elliott

In this case, we need to begin by asking whether the phenomenon really exists. What evidence do we have that people really do act crazy on a full moon? Have we really measured the effect of a full moon on people's behavior? If so, then we should also ask how reliable those measurements are. This might sound like we're being overly skeptical just for the sake of dismissing a neat mystery, but please understand that this is how good scientists always work. We check and double-check everything; it is called verifying our results. After all, it would be wasteful to spend lots of time and energy working to explain something that doesn't really happen.

So we always start by describing a phenomenon as carefully as we can. We also should read about what other scientists have done to describe the phenomenon. In the case of your question, several groups of scientists have looked to see whether the full moon phenomenon really happens, and to date, nobody has ever been able to demonstrate it conclusively. A few studies have claimed to observe tiny increases in rates of traffic accidents and small crimes during full moons. However, most of those studies have subsequently been shown to be mistaken, for various reasons. Because we don't have reliable evidence that the full moon actually does influence human behavior, there is little reason for us to spend time trying to come up with an explanation. Here is a very good web site reviewing the full moon literature:

If you are interested in the full moon's influence on human behavior, then I would encourage you to think about investigating the phenomenon. Think about how you might measure "craziness" and how you could go about making those measurements. Think about what kind of evidence would be convincing to you and convincing to other people. Read the articles referenced in the web site above and see what other scientists have found. You can decide for yourself whether you agree with their conclusions.

Please understand, skepticism does not mean that we should never take mysteries seriously. There really are mysterious phenomena that are easily observable and repeatable. For example, we find that objects fall to the ground in a very reliable fashion and so that is a phenomenon we would like to explain. We call that phenomenon gravity and we have studied it and described it in great detail, but we can't say that we really understand why it happens. Gravity is a natural mystery that is well worth studying.

C. Perkins

There is no scientifically studies that I am aware of that conclude that people act crazier on full moon nights than at other times. It is a myth that has been around for a long time, but I don't think it's true.

Vince Calder

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