We all know the full moon doesn’t turn people into hairy, scary werewolves (at least not without some Hollywood magic). But if other animals respond to the moon, why not people?
Scientists have investigated possible links between the moon and a broad range of human experiences. Some scientists have looked at rates of births, visits to emergency rooms or heart-disease events. Others have considered episodes of mental illness, aggression or crime. Some have even questioned whether the moon can impact ups and downs in the stock market. Much of the evidence is inconclusive or contradicts other data. For every study that finds, for instance, that people lose sleep during a full moon, there’s another study that says — hold on — there’s no link. One thing that does seem clear: It’s just a coincidence that the average length of a woman’s menstrual cycle (28 days) nearly matches the 29.5-day lunar cycle.
“It’s really hard to find definitive answers,” says Davide Dominoni. Why? Because most studies looking for a link between human behavior and the moon “are correlational,” points out this ecologist at the University of Glasgow in Scotland. It’s important to realize that correlations do not prove causation. Indeed, any effect that’s seen could be real. It also may be simply due to some unrelated factor.
In fact, much research has relied on data from studies that had not been looking for moon effects. What’s needed, researchers argue, are experiments with clear hypotheses seeking to probe how the moon might sway our behavior or how the body functions. Until then, they note, it’s hard to say if the moon’s hold over people is fact or fiction.
average (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
behavior The way something, often a person or other organism, acts towards others, or conducts itself.
correlation A mutual relationship or connection between two variables. When there is a positive correlation, an increase in one variable is associated with an increase in the other. (For instance, scientists might correlate an increase in time spent watching TV with an increase in rates of obesity.) Where there is an inverse correlation, an increase in one value is associated with a drop in the other. (Scientists might correlate an increase in TV watching with a decrease in time spent exercising each week.) A correlation between two variables does not necessarily mean one is causing the other.
data Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.
ecologist Someone who works in a branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
emergency room Also known as the ER. It's that part of the hospital where doctors initially attend to the immediate medical needs of accident victims and others who need critical care.
factor Something that plays a role in a particular condition or event; a contributor.
fiction (adj. fictional) An idea or a story that is made-up, not a depiction of real events.
link A connection between two people or things.
lunar Of or relating to Earth’s moon.
moon The natural satellite of any planet.
range The full extent or distribution of something. (in math or for measurements) The extent to which variation in values is possible. Also, the distance within which something can be reached or perceived.
Journal: V.V. Vyazovskiy and R.G. Foster. Sleep: A biological stimulus from our nearest celestial neighbor? Current Biology. Vol. 24, June 14, 2014, p. R557. doi: 10.1016/j.cub.2014.05.027.
Journal: C. Cajochen et al. Evidence that the lunar cycle influences sleep. Current Biology. July 25, 2013. doi: 10.1016/j.cub.2013.06.029.