The idea that a full moon somehow affects human behavior has been around for, well, at least 1,500 years, when it was linked (wrongly) to epileptic seizures.
Later, mental disorders — particularly maniacal episodes — were blamed on the full moon. That’s how we got the terms lunatic and lunatic asylums (which were essentially prisons for the mentally ill).
Those associations have long been debunked. As I’ve noted here before, studies have shown that suicide rates, admissions to psychiatric hospitals and community-based consultations for depression are not influenced by the phases of the moon.
But not everybody — not even all health care professionals — are willing to give up on the ancient idea that the moon exerts some kind of influence over human biology and behavior.
One of the strongest of those persistent beliefs has to do with the effect of the full moon on sleep. And in this area, researchers have found some evidence to at least suggest a link. Two studies (including one I’ve written about in Second Opinion) have reported that people’s sleep tends to decrease by an average of 20 to 25 minutes around the full moon. The quality of the sleep, which was tested in laboratory settings (where moonlight would have no direct effect), was also decreased.
But those studies involved only small numbers of people, a factor that greatly weakens their findings. Indeed, a much larger study, involving more than 2,000 Swiss adults, has since reported that the moon’s phases have no significant influence on sleep.
Then, last year, a group of Danish researchers said they had observed that children tended to sleep longer and to be less physically active around the full moon. The number of children in this study was large (almost 800), but the differences in sleep and activity were small: an average of three minutes of increased sleep and four minutes of decreased activity. The findings, therefore, may not be meaningful.
The latest study
That brings us to yet another study, published recently in the journal Frontiers in Pediatrics. Its authors — a team of international researchers, led by Jean-Philippe Chaput at Eastern Ontario Research Institute in Canada — also set out to determine what, if any, effect the full moon has on children’s sleep and activity patterns.
“This issue may be particularly relevant to children because they are more amenable to behavior change than adults and their sleep needs are greater than adults,” the researchers point out.
Their findings are going to disappoint anybody who believes in lunar influences, however.
For the study, Chaput and his colleagues analyzed data collected from 5,812 children, aged 9 to 11, from 12 countries (the United States, the United Kingdom, Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal and South Africa). The children, who came from a variety of economic and sociocultural backgrounds, were participants in a large multinational study on the effects of lifestyle and environment on childhood obesity.
As part of that broader study, the children had worn watch-like motion-sensing devices (similar to a Fitbit), which tracked their sleep and activity patterns. Chaput and his colleagues compared those patterns at different phases of the moon: full, half and new.
The researchers went into the study expecting to find that, contrary to the earlier Danish study, children sleep less during a full moon and that, as a result, they are also less active during that segment of the lunar cycle.
That is not what the data revealed, however. Instead, it showed no difference, based on the moon’s phases, in the children’s daytime activity levels. The researchers did find, however, a difference in sleep duration: The children slept, on average, about 1 percent — or 4.9 minutes — less per night at full moon than at new moon.
That difference might be explained by the brightness of moonlight, which could be delaying the children’s sleep. “However, the abundance of artificial light in modern societies where most of us spend evenings and nights indoors suggests that this explanation is unlikely to be valid,” Chaput and his co-authors write.
Not all that significant
Ultimately, whatever the cause of the children’s shorter sleep pattern, it may not matter.
For, although sleeping for an average of five fewer minutes may be statistically significant, it’s not all that relevant in terms of its impact on children’s health, the researchers point out.
“Given our large sample size, finding a statistically significant shorter sleep duration around full moon is not surprising,” write Chaput and his co-authors. “From a clinical standpoint, the magnitude of this effect is unlikely to be important.”
Or, as Chaput said in a statement released with the study: “Overall, I think we should not be worried about the full moon. Our behaviors are largely influenced by many other factors like genes, education, income and psychosocial aspects rather than by gravitational forces.”
Now there’s a non-loony idea.
FMI: You can read the study by Chaput and his colleagues on the Frontiers in Pediatrics website.