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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Lunar effect | 2/4 | https://en.wikipedia.org/wiki/Lunar_effect | reference | science, encyclopedia | 2026-05-05T09:22:30.169912+00:00 | kb-cron |
==== Law and order ==== 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. A spokeswoman for the police force said "research carried out by us has shown a correlation between violent incidents and full moons". A police officer responsible for the research told the BBC that "From my experience of 19 years of being a police officer, undoubtedly on full moons we do seem to get people with sort of strange behavior – more fractious, argumentative." 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 Miami-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. A 2009 study of over 23,000 aggravated assaults in Germany between 1999 and 2005 found no correlation with lunar phases. A 2016 study comparing indoor and outdoor crime in the District of Columbia found that the intensity of moonlight had no effect on indoor crime, but a positive effect on outdoor criminal activity. The study's authors speculated that the effect may be due to criminals being better able to assess potential victims and unsecured properties, and there being more such victims out on the street on lighter nights.
==== Motorcycle fatalities ==== A study of 13,029 motorcyclists killed in nighttime crashes found that there were 5.3% more fatalities on nights with a full moon compared to other nights. The authors speculate that the increase might be due to visual distractions created by the moon, especially when it is near the horizon and appears abruptly between trees, around turns, etc.
==== Stock market ==== Several studies have argued that the stock market's average returns are much higher during the half of the month closest to the new moon than the half closest to the full moon. The reasons for this have not been studied, but the authors suggest this may be due to lunar influences on mood. Another study has found contradictory results and questioned these claims.
==== Meta-analyses ==== A meta-analysis of thirty-seven studies that examined relationships between the Moon's four phases and human behavior revealed no significant correlation. The authors found that, of twenty-three studies that had claimed to show correlation, nearly half contained at least one statistical error. Similarly, in a review of twenty studies examining correlations between Moon phase and suicides, most of the twenty studies found no correlation, and the ones that did report positive results were inconsistent with each other. A 1978 review of the literature also found that lunar phases and human behavior are not related.
=== Sleep quality === A 2013 study by Christian Cajochen and collaborators at the University of Basel suggested a correlation between the full Moon and human sleep quality. However, the validity of these results may be limited because of a relatively small (n=33) sample size and inappropriate controls for age and sex. A 2014 study with larger sample sizes (n1=366, n2=29, n3=870) and better experimental controls found no effect of the lunar phase on sleep quality metrics. A 2015 study of 795 children found a three-minute increase in sleep duration near the full moon, but a 2016 study of 5,812 children found a five-minute decrease in sleep duration near the full moon. No other modification in activity behaviors were reported, and the lead scientist concluded: "Our study provides compelling evidence that the moon does not seem to influence people's behavior." A study published in 2021 by researchers from the University of Washington, Yale University, and the National University of Quilmes showed a correlation between lunar cycles and sleep cycles. During the days preceding a full moon, people went to bed later and slept for shorter periods (in some cases with differences of up to 90 minutes), even in locations with full access to electric light. Finally, a Swedish study including one-night at-home sleep recordings from 492 women and 360 men found that men whose sleep was recorded during nights in the waxing period of the lunar cycle exhibited lower sleep efficiency and increased time awake after sleep onset compared to men whose sleep was measured during nights in the waning period. In contrast, the sleep of women remained largely unaffected by the lunar cycle. These results were robust to adjustment for chronic sleep problems and obstructive sleep apnea severity. As for how the belief started in the first place, a 1999 study conjectures that the alleged connection of moon to lunacy might be a 'cultural fossil' from a time before the advent of outdoor lighting, when the bright light of the full moon might have induced sleep deprivation in people living outside, thereby triggering erratic behaviour in predisposed people with mental conditions such as bipolar disorder.
== Other organisms ==