What is a lunatic? The dictionary definition of a “lunatic” is an insane person (no longer in technical use; now considered offensive); a person whose actions and manner are marked by extreme eccentricity or recklessness. The word “lunacy” however has an interesting origin, it originates from the Latin word for moon: luna. How did the Latin word for moon come to mean someone is, in essence, crazy? There’s an ancient and interesting history there.

I’m sure at some point in your life you’ve heard someone say something along the lines of, “Tonight’s a Full Moon. Watch out!” or you’ve encountered people who blame strange occurrences and behaviors on a Full Moon. The Full Moon has been associated with strange behavior and happenings for hundreds of years. A superstitious belief existed in Medieval Europe that the phases of the moon could cause insanity or madness in certain individuals. People who displayed this madness were often deemed to be lunaticus from the Latin for “moon-struck” because their moods and behaviors were thought to be influenced by the changing phases of the moon. The effect of the moon on people’s mental health has also been reported in ancient writings from the Assyrians and Babylonians. In 19th-century England, lawyers used the “guilty by reason of the Full Moon” defense to claim that their “lunatic” clients could not be held accountable for acting under the Moon’s influence. The significance of the Full Moon, however, is that the height of a “moon-struck” individual’s erratic behavior is during the presence of the Full Moon. There is also plenty of anecdotal evidence from individuals working in the mental health field, law enforcement, and medical field that clients and patients display more intense symptomology and extreme behavior during the Full Moon.

There have been scientific studies of a phenomenon known as the “lunar effect”. The lunar effect is “a real or imaginary correlation between specific stages of the roughly 29.5-day lunar cycle and behavior and physiological changes in living beings on Earth, including humans”. Some of the possible purported reasons for the effect have been the amount of moonlight, the presence of water in the human body (proposers of this belief state that the moon controls tides, so why not the water of the human body? This is a pseudo-scientific claim that does not take into account the differences of mass of water in the ocean compared to humans), our evolution and our innate fear of darkness, the increase of positive ions during a Full Moon (this is also a pseudo-scientific claim), and the monthly cycle of human menstruation as it may relate to the lunar cycles. By the late 1980’s there were dozens of studies that looked at the lunar effect, including the Full Moon, on human behavior. However, none of these studies have found a significant correlation between the phases of the moon and the way people behave.

What possible evidence exists that the Full Moon has an effect on the way we think and behave? Two studies found evidence that those with mental disorders i.e. Schizophrenia generally exhibit 1.8% of increased violent or aggressive episodes during the Full Moon, but a more recent study found no such correlation to that of individuals without Schizophrenia. Another analysis of mental-health data found a significant effect of Moon phases, but only on Schizophrenic patients. Such effects are not necessarily related directly to the appearance of the Moon. Disclaimer: Please keep in mind that individuals with Schizophrenia are usually not violent and that this is a dangerous and negative stereotype that exists. A study into epilepsy found a significant negative correlation between the mean number of seizures per day and the fraction of the Moon that is illuminated, but this correlation disappeared when the local clarity of the night sky was controlled for suggesting that it is the brightness of the night sky, and not the lunar phase per se, that influences the occurrence of epileptic seizures with advanced photosensitive epilepsy.

Police officers have also reported increased crime during a Full Moon. Senior police officers in Brighton, UK, announced in June 2007 that they were planning to deploy more officers over the summer to counter trouble they believe is linked to the lunar cycle. This followed research by the Sussex Police force that concluded there was a rise in violent crime when the Moon was full. Police in Ohio and Kentucky have blamed temporary rises in crime on the Full Moon. In January 2008, New Zealand’s Justice Minister Annette King suggested that a spate of stabbings in the country could have been caused by the lunar cycle. A reported correlation between Moon phase and the number of homicides in Dade County was found, through later analysis, not to be supported by the data and to have been the result of inappropriate and misleading statistical procedures.

There have also been some studies on how the lunar cycles affect sleep in humans. A study by the University of Basel in Switzerland established a sleep study that looked for the effect of lunar cycles on human sleep quality, and made sure to control for variables such as increased light at night. The researchers found that the lunar cycles did have an effect on quality of sleep; they found that during a Full Moon the study participants deep sleep decreased by 30%, the time it took for them to fall asleep increased by five minutes, and total sleep duration was decreased by 20 minutes. Some researchers have criticized this study for its small sample size (33 participants) and lack of control for age and sex. However, sleep plays a huge role in an individual’s mental health, and sleep deprivation can have many negative side effects on mental health, and it would be interesting to see other studies research how lunar cycles affect human sleep.

Scientific studies have found no concrete evidence to suggest that the cycles of the moon or the Full Moon have a significant effect on human behavior and mood. If anything, it is the concept of a confirmation bias (when an individual seeks out information that supports their beliefs, and ignores the evidence that debunks their beliefs) that continues to reinforce the idea that the Full Moon plays a role in mental health. However, in the spirit of Halloween, it doesn’t hurt to look up at the Full Moon, which this month is Sunday the 19th, and imagine that spooky and wonderful things are about to occur. From all of us at Capital EAP, have a happy and safe Halloween!


By: Marion R. White, MHC-LP