"You don't understand. Every night when the moon is full, I turn into a wolf." Wolfman (Lon Chaney Jr.)

"You and fifty million other guys!" Wilbur (Lou Costello)

— from "Abbott and Costello Meet Frankenstein"

Hear that howling? Eeeeeeerie. Eeeeeeerie. There's a fu-u-ll moon tonight. When it rises just before sunset, shadowy figures will flit the streets. Police calls will get strangely violent. Emergency rooms will see a surge of weird, scary patients. The man next to you just grew fangs. The dog has begun to look at you funny. The tidal pull of the moon is loosing its primitive, powerful lunacy on the psyches of men and beasts.

Yeah, right.

Let's just separate the "facts" from the fantasy here.

Beasts go mad

"Fact": A Bradford, UK Royal Infirmary study of emergency room animal bite cases 1997-99 showed "the incidence of animal bites rose significantly at the time of a full moon." And University of Washington neuroscientist Eric Chudler said the full moon does seem to affect tidal creatures. Some species of fish breed more aggressively during full moons.

Fantasy: The UK study and others like it were short-term studies with a relatively small number of samples that don't take into account other factors such as weekends or holidays that might contribute to increases, Chudler said. The majority of studies don't show a correlation. And correlation isn't cause. "Any time a study is done there's the possibility something will happen by chance."

Roberto Refinetti, University of South Carolina professor, has studied circadian rhythms, or daily cycles, in lab animals for years and found moon phases had no effect on their behavior.

People go mad

"Fact": Mental disorders, depression and suicide attempts increase during a full moon.

Fantasy: Medical professionals widely believe that urban legend, Chudler said. But when the phenomena are studied, the numbers just aren't there. "Can you seriously say you ever felt the pull of the moon? If that were the case we should see it twice a day like the tides."

Refinetti thinks the legend grew from medieval reports of asylum patients acting up during full moons, which actually was true in the days before electric lights. More light aggravates sleep disorders and some mental illnesses. But, "in comparison to the sun, the moon is nothing. It might affect some people, but the effect would be very, very small," he said.

Babies get made

"Fact": More babies are conceived or born during full moons.

Fantasy: Chudler won't go there; he hasn't studied it.

Refinetti thinks the idea might have grown from the human monthly menstrual cycle, which seems to track phases of the moon. But "it's pure coincidence that humans menstruate monthly," he said. Other animals menstruate at widely different times.

Crime happens

"Fact": Aggression, violent crime and car wrecks occur more frequently during full moons.

Fantasy: Like the emergency room urban legend among medical professionals, this one circulates widely among law enforcement personnel, Chudler said. Some studies seem to prove it; other studies actually suggest the behaviors increase during a new moon. "How do you make sense of that?" Chudler said. Besides the "chance" factor in studies, there's the suggestion factor, he said. Because so many believe it, they look more closely for it — and find it because they're looking for it. It's self-fulfilling prophecy.

Refinetti's circadian rhythm studies show the same thing. "There is no evidence that a full moon affects human behavior anything beyond what a horoscope does: If you read a horoscope you may change your behavior."