What if I told you there really is no full moon effect?

There are several widely believed myths that actually have no reasonable support for them – ghosts as spirits of the dead, UFOs as alien spacecraft, and moon madness, strange effects brought on by a full moon.

“Whoa,” you say. “The full moon definitely has an effect, I’ve seen it myself.”  Lots of people accept that it does. But that does not make it true.

Full-MoonIt’s an extremely common and strongly held cultural belief that the full moon is influential on crime, violence, accidents, strange behavior, and birth rates among other things. But, as I said, there is no basis for this. Don’t believe me? I figured you might not. This myth is a very difficult one to argue against since it is entirely based on cultural information that we have been told is “true” since the time we were kids and associated the full moon with werewolves, lunacy, and a crazy night in the emergency room. Luna, Latin for moon, is the root of the word lunatic. We use it as a go-to reason whenever we notice a strange events pattern to the day or night – “Must be a full moon”.

full moon monster

Study after study have shown the there is no increase in episodes of madness, disasters, traffic accidents, emergency calls, assassinations, violent crime, sleepwalking, births, suicides, homicides, arson, epilepsy, or werewolf sightings associated with the moon phases. Long ago, lunacy laws were on the books in England. A lawyer representing a client could claim a defense of moon madness and be off the hook for temporary insanity. We don’t have such laws anymore because it’s nonsense.

Here are a few sound reasons why the moon myth is NOT true, based on science and collected evidence. All I can do is HOPE you consider them.

  1. The moon is too far away to have a gravitational effect on a person. This is a basic physics calculation that negates the claim that the moon is exerting a gravitation force on people making them behave strangely.  The moon’s gravity affects the Earth because the moon and Earth are both big and near each other. The strength of the tidal force is associated with the alignment of the sun, Earth and moon, not the phase of the moon. Each of us as individuals are small and far away from the moon. Researchers Rotton and Kelly calculated that at birth, a 55 kg mother holding her baby exerts 12 million times more tidal force on the child than the moon because she is close and comparatively big. The moon’s gravity exerts a negligible amount on us. [Source: Kelly, I. W., James Rotton, and Roger Culver. “The moon was full and nothing happened.” Skeptical Inquirer 11 (1985): 129-133.]
  2. A full moon appears as it does due to the reflection of the sun off the surface. The moon does not radiate its own light or any other substance (such as crazy rays).  How can reflected light from so far away be the cause of such claims? There is no basis for it.
  3. If there was such an effect, it would be obvious when we attempt to count events during a full moon phase. However, many studies of data sets have attempted to measure accidents, injuries and illness, crime statistics, etc. and it’s NOT obvious. Occasionally, one study may show a small effect but when reasonable controls are applied to the data, the effect disappears. The corrections include allowances for days of the week, weather, or other factors that could influence the frequency of certain events (like, car accidents or violent altercations).  Also, how events are recorded or counted is critical – if it really occurs during a full moon phase. When we account for all these real-world complexities (or attempt to account for them all), we find that  the lunar effect disappears.
  4. In modern culture, we are primed to accept such a belief so we remark upon it often and especially when we NOTICE a full moon and can conveniently ascribe strange events to it. But we don’t remember the times where it wasn’t a full moon or we just assume there was and do not check. This is called confirmation bias which reinforces our accepted beliefs, reminding us that we are correct in our view of the world. (But we really aren’t.)

So, there you have it. The full moon has no measurable, physical influence on people’s actions, behaviors or physiology. Believe it or not.


You may still choose to believe in full moon madness for various reasons. Essentially, believing in it is harmless and likely will not cause you (much) misfortune in life. But the core of practical skepticism is about asking if there is a good basis for accepting a claim as true and making an effort to understand the best causes behind a phenomenon. It CAN be very dangerous to believe something that isn’t true or is misleading. As the author of the most recent paper on the myth of the full moon, Jean-Luc Margot, points out,  there are many similar beliefs that are common and widely held that ARE dangerous to society: belief that autism is caused by something in vaccines has caused an outbreak of vaccine preventable diseases, superstitions about magical effects from rhinoceros horns are hastening their extinction,  incorrect beliefs about the reality of climate change result in delays in action or no action to mitigate the worsening effects. Unfounded belief can cause harm; it’s better to know the best answer, not a misconception.

Perhaps next time a “wild” day at work or home occurs, you’ll pause to rethink your response about the cause. Take a deep breath and say “This crazy stuff just happens.”


6 thoughts on “What if I told you there really is no full moon effect?

  1. Steven Thornquist says:

    Actually, it depends on how you look at the data. I often point out to people who remark on the full moon that there is strong scientific evidence that most odd behavior occurs within plus or minus two weeks of a full moon.


  2. Victoria says:

    I once worked in a psych hospital where the nurses were convinced there was increased unrest and hospital admissions during full moons – so I kept track of the moon, admissions numbers, and incidences involving patients becoming agitated/violent etc. Even after showing them there was no correlations, their response was, “I’ve seen it! I know it’s true!”



    • Chief Eric says:

      I agree, the Full Moon does have an effect on those who are mentally weak, those who are alcoholics and drug abusers. I spent over 24 years on the police force, and have seen it regularly, domestic calls increase, and some of the worst times of my career happened during a full moon period. Like the old fellow in the town hall office told me – figures don’t lie, lier’s figure.


      • idoubtit says:

        As I’ve said, people believe this but over and over, the data does not back it up. So, it’s not correct to make this claim as true.


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