Does the Full Moon Affect Humans?

A human shape-shifts into a werewolf with a full moon in the background
Werewolf stories are among the most ancient myths about the full moon

It is an impressive sight when the moon is full and round in the night sky. Many people believe that the full moon affects human behavior and health. Today, esoteric lunar calendar guides fill entire shelves in bookstores. However, there is little truth to that. In this article we provide scientific explanation to some of the most widespread myths about the influence of the full moon on humans.

While some claims about effects a full moon has on humans become common knowledge, others are at most considered fairy tales – or does someone actually believe in the existence of werewolves? Here’s a list of seven full moon myths debunked:

The full moon affects sleep

One of the most popular myths about how full moon affects humans has to do with sleep. Many people believe that they are less able to fall asleep or sleep more restlessly under a full moon. Light is often held responsible for this. After all, the three nights at full moon are twelve times as bright as a crescent night. And it is known that light affects the pineal gland which secretes a hormone called melatonin (sleep hormone) during the dark cycle. Another possible reason is psychological: if you worry about sleeping poorly on a full moon, you may actually sleep worse – in a sense, a self-fulfilling prophecy.

So far, however, scientific studies have not been able to prove a causal connection between full moon nights and sleep disorders – with one exception. A study by Swiss researchers from the University of Basel found in 2013 that the test subjects in the sleep laboratory needed five minutes longer to fall asleep under a full moon. In addition, the total length of sleep was reduced by 20 minutes and the deep sleep phases were 30 percent shorter.

However, the study has some weaknesses, as the researchers themselves admitted. The number of full moon nights examined was very small, there were only 33 subjects and the examination only lasted three and a half days for the individual test subjects. They were also not asked whether they believed in the full moon or not. Therefore, an influence of the full moon on sleep is still not scientifically proven.

To find out more about the moon and its phases: How old is the moon and how did it form?

More babies are born when the moon is full

Another common belief about the way full moon affects humans is that more children are being born during this period. This idea, which only emerged at the end of the 19th century, is widespread. But the statistics show that there is nothing to it. Both astronomy professor Jean-Luc Margot from the University of California and sociologist Edgar Wunder from Heidelberg University come to the same conclusion. In his 2015 study, Margot attributes the myth primarily to the bias of some professionals in the maternity ward of hospitals and the lack of statistical methods. Studies that postulate a connection between the full moon and the birth rate could never have been reproduced.

In contrast, the clear majority of large-scale studies and meta-studies on the topic were unable to demonstrate such a connection. This also includes the most extensive study so far in terms of the number of examined lunar cycles. This study was carried out at the Martin Luther University Halle-Wittenberg and analyzed more than four million births. Additionally, researchers found no correlation between moon phases and number of births.

As part of the meta-study, the researchers took a close look at several studies from different countries, in each of which they had found a tiny significant effect. However, only in different phases of the moon. A French study from the 1980’s showed that most births took place before the new moon. Wunder also points out that prejudice and perceptual distortions in affected professionals strengthen the belief in a connection between birth rate and full moon.

There are more accidents and crimes when the moon is full

When the moon is full, hospitals and police stations are busier than usual – many believe that. Under the influence of the full moon, some people are more scattered and irritable, so there are more accidents and crimes. But here too – just like the myth of the rising number of births under a full moon – the facts do not support the assumption. Margot’s previously mentioned study also refuted this supposed connection. On full moon nights, on average, no more patients are admitted to the emergency room than usual.

Researchers admit that many police officers are convinced that accidents and violent acts occur more frequently on a full moon. Here too, however, he refers to the mechanisms of selective perception. We do not store all incidents from everyday life in our memory, but rather keep those we have noticed. For example, a police officer would perceive an accident site over which a full moon hangs as something special and accordingly remember it more easily, while he would rather forget an incident without a moon. This distorts his subjective statistics. In addition, the media tend to mention a full moon as a fact in the reporting of a misfortune or crime – but hardly a crescent moon.

The full moon pulls sleepwalkers out of bed

Much is said of the ways a full moon affects humans – including that it causes sleepwalkers to get out of bed. So, the sleep disorder somnambulism (sleepwalking) was once also called lunatism. The grain of truth in this notion is that sleepwalkers generally move towards a light source. And in the past, the moon was usually the only source of light at night, and the full moon was very special.

This is no longer the case today. The moon is only one of many light sources. Nonetheless – since the full moon seems much brighter than the crescent moon as mentioned at the beginning – on full moon nights the probability increases a little that people prone to somnambulism actually sleepwalk. A good antidote is to darken the bedroom using blinds or curtains.

Operations are riskier when the moon is full

In esoteric guides it can sometimes be read that planned medical interventions on a full moon are better to be avoided. The risk of particularly severe blood loss and the risk of complications would then be higher. It is better to be operated on when the moon is waning. This is based on the general idea that in the waning phase of the moon assisting relief and recovery. While conversely, injuries are more intense with a waxing moon.

However, numerous empirical studies have tested whether operations during full moon are riskier. All of these have come to the same conclusion, full moon does not affect human well being after surgery. It does not matter at which moon phase the surgeon performs and operation. One example among many is a study published in 2011 by scientists from Saarland University Hospital. Researchers analyzed 27,914 cases of patients who had to undergo surgery between 2001 and 2010 and compared the data with 111 lunar cycles. The researchers were unable to correlate noticeable blood loss or the number of emergencies with a specific moon phase.

A study by the Ludwig Maximilians University in Munich in 2009 came to the same conclusion. In this study, researchers statistically evaluated postoperative complications and the mortality rate in 2411 lung cancer patients. There was no significant connection with the phases of the moon.

The female cycle lasts 28 days on average – almost as long as a lunar cycle that lasts 29.5 days. This striking coincidence has probably led to the fact that the view that the moon influences the menstrual cycle enjoys great popularity. Especially in esoteric circles, people believe that without the influence of artificial light, women menstruate on new moon and ovulate on full moon. In fact, there are animals like the Palolo worm, which lives in coral reefs in the South Pacific, and which reproduce in sync with the lunar cycle. But researchers weren’t able to prove such an association in humans. So, data from 1.5 million women using a menstrual calendar app, showed that there is no correlation between the lunar and female cycles.

The anthropologist Beverly Strassmann from the University of Ann Arbor in Michigan also found no connection between the menstrual cycle and the moon phase in her study published in 1997. She had examined 477 menstrual cycles of 58 women from the Dogon ethnic group in Mali. These women did not have access to contraception or electricity. Strassmann was therefore able to rule out chemical and physical influences on the biorhythm of women.

The full moon is effective against warts

In folk medicine, the full moon affects humans in a positive way, it has healing powers. At-least, when it comes to warts. These skin changes caused by viruses can be extremely persistent and, in some cases, oppose conventional medical treatments . In addition to numerous strange household remedies, in some the full moon plays an important role.

A little more elaborate is the instruction to go out to a meadow after a full moon night. Then, to find a slug there and let it crawl over the wart. The recipe from Russia is to run your hand over a wall illuminated by the waning moon. Then run it down and down over the wart. One should repeat the procedure several nights.

Interestingly, these home remedies are effective to some extent. However, the influence of the moon is unlikely to play a role. Rather, the strange therapies stimulate the immune system through suggestion, which can make warts disappear – thanks to the placebo effect. In any case, many warts regress themselves after some time. In about 60 percent of cases, spontaneous healing occurs within two years.

More answers to curious questions about the moon:

Why does the moon have bigger craters on the side facing earth?

What would earth be like without a moon?

Why is the moon visible during the day?

Does the moon look the same everywhere?


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