Moonstruck! Does The Full Moon InfluenceBehavior?

Ithappens at least once every month. Sometimes, rarely, it happens twice amonth. Up there in the sky. It's a bird. It's a plane. No, it's a FULLMOON. Popular legend has it that the full moon brings out the worst in people:more violence, more suicides, more accidents, more aggression. Theinfluence of the moon and behavior has been called "The Lunar Effect" or"The Transylvania Effect." The belief that the full moon causes mentaldisorders and strange behavior was widespread throughout Europe in themiddle ages. Even the word "lunacy" meaning "insanity" comes from theLatin word for "moon."

You may hear people say, "Just ask an emergencyroom nurse or a police phone operator. They will tell you that they arebusier on nights when there is a full moon." Is there scientific evidence to support these beliefs? Let's look at thedata.

Violence, Aggression and Crime 11,613 cases of aggravated assault in a 5-year period: assaults occurred more often around the fullmoon. Reference: Human aggression and the lunar synodic cycle 34,318 crimes in a 1-year period: crimes occurred more frequently during the full moon. Reference: J.Psychology, vol. 93:81-83, 1976. 58,527 police arrests in a 7-year period: nodifference in the number of arrests made during any phase of themoon. Reference: Antisocial behavior and lunar activity: a failure to validate the lunacymyth 361,580 calls for police assistance in a 3-year period: no relationship to the phase of the moon when day of theweek, holiday and year were controlled. Reference: Perceptual and Motor Skills, 57:993-994,1983 1,289 aggressive "incidents" by hospitalized psychiatricpatients in a 105-week period: no significantrelationship between the severity or amount of violence/aggressionand phase of the moon. Reference: Lunar cycles and violent behaviour The rate of agitation in 24 nursing home residents in a 3-monthperiod: no significant relationship to moonphase. Reference: Full moon: Does it influence agitated nursing homeresidents?

Anxiety, Depression and Psychosis The records of 782patients and4,600 consultations in an 18-year period: norelationship between the phase of the moon and the number oftimes people contacted their doctors for anxiety or depression. Reference: Lunar cycle and consultations for anxiety and depression in generalpractice. The admission records of 18,495 patients to a psychiatric hospitalin an 11-year period: admissions for psychosis werehighest during the new moon and lowest during the full moon. Reference: Lunar madness: an empirical study 25,568 psychiatric emergency room visits in a 13-year period: visitsincreased near the first quarter moon and adecreased around the new moon and full moon. Reference: Human aggression and the lunar synodic cycle

Suicides 928 suicides in a 4-year period: suicides did notincrease during the full moon. In fact, more suicideswere noted during the new moon. Reference: Lunar association with suicide. 897 suicides committed in a 3-year period: norelationship to the phase of the moon. Reference: Suicidesand the lunar cycle 504 suicides committed in a 1-year period: norelationship to the full moon. Reference: The Moon and Suicide 383 cases of attempted suicide in a 1-year period: no relationship to phase of the moon. Reference: Attempted suicide and the lunar cycle 1,997 suicides in a 13-year period: suicides didnot occur more often during the full moon. Reference: Human aggression and the lunar synodic cycle 4,190 suicides in a 58-year period: suicides had norelationship to the phase of the moon. Reference: Variation in suicide occurrence by time of day, day of the week, month,and lunarphase 1,187 cases of "self-poisonings" in a 1-year period: no relationship to the phase of the moon. Reference: Self-poisoningand moon phases in Oslo 841 cases of "self-poisonings" in a 4-year period: self-poisonings did occur more often on the day of the fullmoon. Reference: Full moon and poisoning

Emergency Room Calls/Emergency Room Visits/Hospital Admissions Calls to a poison center monitored over a 1-year period:unintentional poisonings occurred more oftenduring the full moon cycle. However, the number of calls due tointentional poison exposure (suicides/drug abuse) was significantly LOWERduring the full moon and higher during the new moon. Reference: Lunar cycle and poison center calls 1,444 trauma victim hospital admissions in a 1-year period: no increase during full moon. Reference: Trauma and the full moon: a waning theory 3,468 emergency room visits and hospital admissions by people whointentionally took poison: visits and admissions were notdifferent on days with full moons. Reference:Lunar cycle and poison center calls 7,844 emergency calls to a suicide prevention/crisis call center in a2-year period: the highest number of total calls was during the newmoon, not the full moon. When calls forsuicide threats were analyzed, there were more calls during the firstquarter of the moon and new moon. Reference: Moonphases and crisis calls: a spurious relationship 36,268 calls to a crisis center in a 8-year period: no relationship to moon phase. Reference: Investigation of periodicity in crisis intervention calls over aneight-year span 736 telephone counseling calls in a 4-month period: norelationship to moon phase. Reference: Psychological Reports, 35:752-754, 1974 100 admissions to a psychiatric hospital in a 3-year period: no relationship to the cycle of the moon. Reference: Lunarphases and psychiatric hospital admissions

Drug Use/Overdose 1,182 drug overdose cases recorded in a15-month period: no relationship tothe full moon phase. Reference: Drug overdose and the full moon 949 cases of drug use (toxicology screenings) in a 1-year period:no relationship to the phase of the moon. Reference: Hospital-based toxicology: patterns of use and abuse

Accidents 246,926 traffic accidents involving propertydamage and 50,492 traffic accidents with non-fatal injuries in a 9-yearperiod: no relationship was found between accidentsand moon phase. However, this research did findthat accidents of both kinds occurred more often on Friday and Saturdayand on Halloween. New Yearâs Eve and Thanksgiving also had higher rates of traffic accidents involving property damage. Reference: Cyclical calendar and lunar patterns in automobile property 2,382 fatal traffic accidents in a 13-year period: accidents were not higher during the full moon. Reference: Human aggression and the lunar synodic cycle 4,835 traffic accidents in a 4-year period: norelationship to the phase of the moon. However, there was anincrease in the number of accidents that occurred in the summer and onweekends. Reference: Human aggression and the lunar synodic cycle Medical staff "incidents" recorded in a 4-year period: no relationship to the phase of the moon. Reference: Don't pass the buck! the full moon is not responsible for an increase inthe occurrence of untoward events in a hospital setting!

Problems Studying the Lunar Effect Perhaps one of thefirst things that you notice about these studies is that the results are inconsistent. Some studies show that a particular behavior willoccur more often during the full moon and other studies show norelationship between behavior and the full moon. This findingalone casts doubt on the theory that the full moon influences behavior.It may also be thatexperiments have been designed differently. For example, some studiesinclude "full moon" behaviors that occur a few days before and after thefull moon, while other studies include only those behaviors within asingle day of the full moon. Selective Memory? Because many people believe that the full moon can affectbehavior, experiments must be designed carefully to eliminate thepossibility that people's beliefs will influence the data. For example,if people know that they are in an experiment which studies the moon itsaffect on behavior, they may act in ways that change the results. It ispossible that people have a "selective memory" for strange events thathappen on the full moon; they remember strange incidents that occurduring a full moon, but forget when these same things happen at othertimes. Correlation Does NOT Mean Causation It is also important to remember that studies that examine relationshipsbetween behavior and the phase of the moon determine only correlations. These types of studies determine if one set of numbers varies in areliable manner with another set of numbers. If they do, then it can besaid that a relationship exists. The existence of a relationship between two "variables" DOES NOT mean that one variable causes theother variable. For example, if you looked for a relationship between thenumber of points scored by a basketball team and the number of bookschecked out of a library on different days, you might find a significantrelationship. This doesn't mean that the score of basketball games causespeople to check out library books or that checking out library bookscauses the basketball team to score more points. The reason why thesetwo activities vary in a similar fashion is completely unknown anduntested. It just happens that the two measurements vary in a relatedfashion. In the basketball/library book example, the relationship could becaused by many things, maybe even by the weather. Maybe there was a lotof rain when the basketball scores and library books were counted. Perhaps the rain caused the basketball players to practice more (resultingin more points scored) and caused more people to visit the library(resulting in more checked-out books). Some experiments do show that on days with a full moon there is moreabnormal behavior. However, many of these studies have been criticizedbecause they were not performed properly. For example, some of theseexperiments: tested only a few people over a short period of time. did not analyze the data with proper statistical tests. did not take into account the day of the week on which the full moonoccurred did not take into account whether the full moon occurred ona holiday or a weekend.

Although mostexperiments fail to show arelationship between the phase of the moon and abnormal behavior, thebelief in the "lunar effect" is still strong among many people. Unfortunately, the occasional newspaper story that describes strangebehaviors when the full moon is out only reinforces thismyth.

Did you know?

The full moon appears once every 29.53 days. The distance between the moon and the earth varies from about 221,463miles (356,334 kilometers) to 251,968 miles (405,503 kilometers). The diameter of the moon is 2,159 miles (3,475 kilometers). Forcomparison, the diameter of the Earth is 7,926 miles (12,756 kilometers). The circumference of the moon is 6,790 miles (10,864 kilometers). Forcomparison, the circumference of the Earth at the equator is 24,902miles (40,075 kilometers). Sometimes there are two full moons in one month. It IS possible to have amonth without a full moon, but this does not happen very often and it canhappen only in the month of February. You will have to wait untilFebruary 2066 for the next month without a full moon.

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