Can a Full Moon Affect Your Mood?

Does the Moon Make People Crazy?

By Tim Clark
February 23, 2021
Full Moon

Does the Moon influence our behavior or emotions? There’s never been solid proof but it turns out there’s some new evidence the Moon can affect sleep on the days leading up the full Moon–and it doesn’t matter if you’re in the country or city! Let’s explore the myths and reality of the Moon’s power.

The Luna-Lunacy Connection

Ancient authorities like Aristotle, Paracelsus, and Pliny the Elder thought some humans were driven crazy by the full Moon. The Latin name for the Moon—“Luna”—is the root of modern words like “lunacy,” “lunatic,” and even “loon,” as in “crazy as a loon.” 

Even today, many doctors, nurses, EMTs, police officers, and elementary school teachers agree that full Moons will bring bizarre behavior—43 percent of healthcare professionals believe in what some call “the lunar influence,” as do 81 percent of mental healthcare specialists. But is there really a lunar connection to abnormal behavior? 

Unless you plan to ask a werewolf (which we don’t recommend), it might be time to separate facts from fiction.


The Moon and Sleep

According to a January 2021 scientific study, people go to bed later and sleep for a shorter period of time in the days leading up to a full Moon. Specifically, people would go to bed 30 minutes later than average and sleep almost an hour less per night!

This makes some sense because the light from the Moon after sunset is brighter on the days leading up to a full moon. However, here’s the surprising part: Studies found that it didn’t matter if you lived in a rural or urban environment (where you might find more electrical lights)! Sleep patterns were compared between people in two very different locations:

  1. Indigenous people in rural Argentina (the Toba/Qom communities) who don’t have any access to artificial light
  2. College students living in downtown Seattle, Washington where the glare from city lights dims the light from the Moon and stars.

If the Moon’s brightness isn’t a factor, why do we stay up later and sleep less?  One theory goes back to our ancestors—and our long human history before the industrial age. People paid attention to the Moon and relied on its “night light” for hunting, fishing, and other social activities. Think of the “Harvest Moon” in the autumn, so-named because it provided several nights of light for farmers to gather in their crops at the height of harvest. Every month, the nights leading up to a full moon bring more light to the evening.

Our sleeping patterns are controlled by our natural circadian rhythms— the day and night cycles driven by Earth orbiting the Sun. But there are also circalunar rhythms, which are tied to lunar cycles. Certainly, some animals will respond to both a circadian rhythm and a lunar clock.

Many animal species’ behavior is influenced by the Moon, too. Think of birds which rely on the Moon for migration and will even time their reproduction to coincide with the specific phases of the lunar cycle.

Anecdotally, you have to wonder if less sleep (whether interrupted sleep or going to bed later) for several nights in a row might lead to some irritability—and what you might call moodiness!

The Moon and Lunacy

That leads us to weird behavior. There have been hundreds of studies about the Moon and lunacy. The few studies that suggest a connection are usually disproved or contradicted by others:

  • One study says more animal bites (from cats, rats, dogs, horses) occur at the full Moon; another says there’s no increase in dog bites.
  • One shows an increase in crime around the full Moon; others find no increase in arrests, calls for police assistance, prison assaults, batteries, or homicides.
  • Admissions for psychosis are lowest during the full Moon, and psychiatric emergency room visits decline; but calls to suicide prevention hotlines peak at the new Moon, not the full Moon.

We’re not quite sure how you’d actually prove the connection between the Moon and lunacy. But one explanation might be what psychologists call “confirmation bias”—people are more likely to notice things that confirm a preexisting belief.

  • If you’re working in an emergency room, and something weird happens on the full Moon, your older and wiser colleagues nod and say, “Must be a full Moon.” That’s what they heard from their elders when they were new at the job. (Psychologists have a name for that, too: “communal reinforcement.”) 
  • But if something weird happens at a different phase of the lunar cycle, nobody says, “Must be the third quarter Moon!” And when nothing unusual happens on the full Moon, nobody says anything.


We call widespread beliefs that are unsupported by fact folklore. Erika Brady, who teaches folklore at Western Kentucky University, says, “it’s a way of imposing order on something that feels frighteningly out of control.”

How does a belief that strange things happen on the full Moon help us feel safer? The full Moon occurs only once every 29.5 days; that means the other four weeks of the lunar month should be less dangerous and unpredictable. See when the next full Moon is.

Therefore, this folk belief implies that our fears about everything from increased bleeding to werewolves may be limited to only 12 or 13 days per year.

Hey! Maybe that’s why the number 13 worries people!

What do you think about the Moon? Does it influence behavior or emotions? Or, is it all in our imagination—and our dreams?



Reader Comments

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Concerning the effect of the Moon on one’s behavior

Disclaimer: this is not to put down anyone who believes that the Moon may affect a person’s behavior. What you believe is entirely up to you.
So, I do not believe that the Moon affects the behavior of people. If that were the case, the men that traveled around and landed on the Moon back in the late 60s and early 70s would have been strongly influenced by the Moon and therefore would have immediately been unfit for space travel (back in those days, psychological tests were very strict to the point of being unreasonable, so mental stability was a huge concern for astronauts). And they had plenty of missions to prove if the Moon affected the astronauts behavior if they wished to do so, particularly Apollo 8-10. But there is no indication of the astronauts being affected by the Moon’s light or the Moon itself. Therefore, I think it is potentially harmful to think that the Moon can affect your behavior, especially if you are interested in scientific research. It can potentially even be sexist if you go farther to say that the Moon affects a woman’s cycle- if that were the case, it wouldn’t be safe to send a woman to the Moon for fear that her body will react to the close proximity of the Moon! We do not need to go back 50 years in our thinking about women and space travel and especially what they can and can’t do. I probably didn’t explain it well, but I hope you understand my reasoning.

Full moon increase in weird behavior

I was a pharmacist for many years. I could always tell when it was a full moon or on the waning cycle. People would act weirder and get more psychiatric meds at this time. I had a technician that didn't believe me. After about 3-6 months, she was convinced. I dreaded working at that time of month.

Moon & woman’s cycle

Interesting article! I would mention the natural woman’s cycle with the moon as well : white woman (ovulating with a new moon ) & red woman (ovulating with the full moon). Something to explore here ...

Full Moons and New Moons

I have been bartending for over 43 years and believe me, I never have to look to the sky to know when it's a Full or New moon. People are a little crazier and a little weirder during these moon phases. They dance more, laugh more and are more outgoing.

Believer of the Full Moon happenings.

My daughter has always been affected by the full moon. Her behavior always was worse during the full
moon and after then she was sweet. But full moon made her very aggressive. It is a sad thing to watch.
to this day she still has problems but tries to control them.

"Full Moons"

Good Dy., good people of 'The' Farmer's Almanac

I am of the belief that activity becomes more vibrant leading [2] dys. during & [2] dys. after all full moons! The water ratio to solids in each of our bodies have the eb & flow aspect of 'tides' whether they be physical as in water of the planet, such as the Fundy Ties in eastern Canada where I was born & raised or the alignment of the planets as they go through there lunar cycle every 29.5 days.! I know from my personal experience that two [2] days previous to a full moon, my attention and pysk & physical being is being pushed into a hyper activity and I am very much more robust then other times of the month! I tend to feel as though I'm on the prowl like a Wolf or Jackal, Hyena! So my 2c. Thanks.

I believe in the full moon affect.

My son has been a paramedic for 15 years and he dreads working on the full moon. He said they are extremely busy.

Well all I know..

is that during a full moon I will have trouble sleeping. Sometimes I will have a rough night and get up just to look at the calendar just to see what phase the moon is in. My wife also claims that I am very restless while trying to sleep on those nights. Just my 2 cents worth..

Junior High School Full Moons

I just know that in the months before I retired from teaching middle school, I was counting off the full moons that remained.

Full Moons

My Irish Mom spoke more about the "moon on it's back", or the "fingernail moon", the last quarter, when she believed more ominous things happened.

The Lunar Connection

If, as they say, the moon affects the tides here on Earth & the human body is made up of 60% water, then I've always believed that it could make sense that the moon could affect us somehow, especially strongest when the moon is at its fullest

Full Moon

Everyone agrees that a full moon affects Mother Earth's tides. Since humans are mostly fluid, who's to say that we don't have tides, too. Feeling is water. Depending on the sign the full moon determines whether our tides are ruled by the modalities of cardinal, fixed, and mutable, and affected by elements of feeling (water), thinking (air), intuition (fire), or sensation (earth).

Full moon effects

I am a Cancer, born on the Cusp 6/22. We are dubbed moonchildren. A lot of time on the night before the fullmoon, and into fullmoon, the pain that i experience every day disappears and i am wide awake. Everyone in my family knows when its a full moon by the way i act. Wish i could harness whatever it is.

Full Moon Effects

Whether the moon is waxing or waning doesn't seem to have the same effect as a full moon, even though the moon is in the sky when the slightest part is visible. So its not gravitation. That leaves me to think the effect is derived from the reflected ions of the solar wind which stimulates people and other living creatures to all types of actions. Ask Walmart employees about their store, and what goes on during the time of a full moon.

Full Moon

My teeth are very sensitive on a full moon. My dentist confirmed that many patients have this same experience. My cat goes crazy on the full moon, tearing around the house and pawing the mini-blinds to see outside as if there's somebody out there. Also - - it isn't just the DAY of the full moon that causes these things - it begins 2 or 3 days before the full moon and continues on until about 2 days after.

Cat at the Window

Your cat has it pegged! The lunar effect is coming from outside where the moon shine is brightest(intensity), though it effects us indoors like an electro-static field. And we know electro-static fields can interact with the same fields in our brain. Also, the 2 days before and after I agree is intense as well because the reduction of moon shine is still reflecting a high percentage of the solar wind, during the moonlight phase called "Gibbous." Then the lunar phases descend to the "new moon" phase which means the moon is on the other side of the earth. Thanks for the cat observation!!

Full Moon effects

As a career Mariner, I finally retired with a new hobby (gardening). The Full moon effect creates the highest & lowest tides of the months. The human body is said to be 98% water. Of course the Full Moon effects humans.

Watermelons are 92% water.

Watermelons are 92% water. How does the moon affect them? The logic has to apply to all organisms.

Full Moon

I have worked in a nursing home for years & yes the Full Moon Does affect people.

Lunar vs. circadian rhythms


I came across two publications in 2013:

Dina Fine Maron, "Phased Out: Human Sleep Patterns Linked to Full Moon," Scientific American, 2013-07-25

Christian Cajochen et al., "Evidence that the Lunar Cycle Influences Human Sleep," Current Biology, Volume 23, Issue 15, pp. 1485–1488, 2013-08-05

Please let me know if there have been further studies on this topic.

Thank you!

Best Regards,



I agree with you. I worked on a skilled nursing unit and noticed the same thing.

Moods/Moon/ Nursing Homes

Oops. Replied to wrong comment.