fact or fiction

Is the ER really any wilder during a full moon? DOs weigh in

Stories of hectic nights in the emergency room during full moons are common, though hard evidence of a correlation “just isn’t there.”

Full moons causing irregular or unexplainable behavior in humans and animals has been a belief for some for centuries around the world.

One group that historically subscribes to this belief is emergency physicians. Anecdotes abound of hectic nights in the emergency room brought on by the brightest phase of the lunar cycle; a 2011 study published in the World Journal of Surgery found that more than 40% of medical staff believe that lunar phases can affect human behavior.

But hard evidence of that correlation, as many physicians would admit, trails far behind. Multiple studies have found no direct correlation between the full moon and hospital admission rates.

That doesn’t stop the phenomena from being a subject of great debate, however. In 2015, when The DO first covered this topic, 32 comments were left below the story sharing vastly differing viewpoints.

One commenter who said they had practiced emergency medicine for 30 years wrote: “Full moons seem to increase usual craziness. My unproven theory, which the students and residents are probably tired of hearing, is that when a low-pressure front approaches summer or winter, the ER gets very busy, then decreases when past.”

Another commenter was less convinced.

“Scary that such a huge proportion of medical personnel is prey to superstition instead of enlightened by science,” they wrote.

Where does the debate stand six years later?

In 2018, Bryan Bledsoe, DO, sought to put an end to the debate once and for all with an article in the Journal of Emergency Medical Services. After sifting through 30 years of studies examining lunar phases and cardiac events, brain aneurysms, kidney stones, psychiatric emergencies, childbirth and general ER visits, he found nothing to suggest any correlations exist.

“The best explanation, simply, is human nature,” he wrote. “Most people will remember and note a full moon because the appearance is so striking. They will then recall EMS runs and certain things that are associated with a full moon. Most people do not even notice the other lunar phases … and do not tend to associate EMS calls with these lunar phases.”

Dr. Bledsoe told The DO that in his research, he did actually find a slight correlation between increased moonlight and vehicle collisions with animals, but that he wouldn’t assume those occurrences are common enough to fill up an ER on a given night. When teaching residents at the University of Nevada-Las Vegas, he uses his research as a learning exercise.

“I have them do exactly what I did when I wrote that article: go to PubMed or any other database and look for full moons and emergency events, and see that the hard evidence just isn’t there,” he said. “It gets people to look up data that doesn’t confirm their held beliefs, which is a valuable lesson in the scientific method. Celestial events don’t impact how we behave down here.”

Mark Mitchell, DO, an emergency physician in Aventura, Florida, was one of several commenters on The DO’s 2015 article who argued in favor of the correlation between full moons and ER activity.

“I completely concur that we seem to have higher volumes and more bizarre presentations during a full moon,” he wrote then.

Reached for comment more recently, Dr. Mitchell conceded that while the phenomena is still widely discussed, it’s not something most ER workers take seriously.

“When we’re all working in the emergency room, and volume is up, and it happens to be a full moon, we just say we should’ve expected it,” he told The DO. “People come in with crazy, bizarre complaints or they’re having behavioral health issues or psychotic issues or have taken drugs. And it probably doesn’t happen any more frequently during a full moon, but we all associate it with them anyway.”

“EMS is just ripe with all these urban legends”

Drs. Mitchell and Bledsoe both said they heard about the full moon phenomena early on on in their careers in emergency medicine, and that young health care workers can sometimes latch on to such tall tales.

“EMS is just ripe with all these urban legends,” Dr. Bledsoe said. “I was a paramedic before I went to medical school, so I heard this legend from the beginning in the late 70s and early 80s, and I think I even believed it some at that time. Obviously, I don’t anymore, but it’s fun. It’s something you’d say to mess with a rookie.”

“People will say all kinds of things to young physicians,” Dr. Mitchell added. “For example, I was told to never say ‘it’s quiet’ because, inevitably, the doors will open up and a lot of people will come in. But, again, that’s all based on confirmation bias.”

It’s the same confirmation bias that might lead one to anticipate a busy night in the ER on New Year’s Eve, Halloween, or just any given Saturday. Both DOs attested that those nights often fail to meet expectations, activity-wise. (Dr. Bledsoe says data found the most active night, on average, in Las Vegas ERs to be Thursdays).

So knowing all that, what keeps the full moon myth alive despite all the evidence to the contrary? The answer is simple: human nature.

“From an evolutionary standpoint, our brain has been taught to look for precursors of danger,” Dr. Bledsoe said. “If you’re walking in your yard and you see a piece of a rubber hose, your first thought is: this is a snake.”

Dr. Mitchell agreed that in this case, believing often takes precedence over seeing.

“Sometimes, you see what you’re looking for,” he said.

The first full moon of 2021 will be on Thursday, Jan. 28.

Related reading:

‘Full moon madness’ in the ER: Myth or reality?

How to make the most of emergency medicine rotations


  1. Michael J. Friedman, D.O.

    I know as a student of science that the data do not support the increased “Lunacy” associated with a full moon. But every month one occurs, I still cringe. I still (either imagined or otherwise) have perceived an increase in psychiatric Crisis Center activity during full moon phases. But like all urban myths, you tend to latch on to the suggestion of a proposed phenomenon, despite scientific evidence proving otherwise. Hey, it’s what makes being human interesting!

    1. Melinda Lee BOYE DO

      Actually I did my paper on this
      FULL MOON least amount absentia from work….Tuesday popular day to be fired,or take one’s life…1 day before and 1 day after full moon increase number of psychosis admits.

      1. David

        Although VOLUME may not be significantly affected, the wacky, time consuming, ridiculous, psychotic complaints DO increase. THAT’S what is, as EM physicians are talking about.

  2. Madhav Manikal

    ER activity is not likely to be a reliable indicator of the influence of Lunar Phases on human behavior- rather it is likely a crude and inaccurate parameter.

  3. Madhav Manikal

    Hollywood Films, Bollywood Films, any number of singers in any language or in any culture all over the world sing songs of romance, love, and heightened emotions in Moonlight and surely on Full Moon settings. ER patient attendance is hardly the metric to judge if the moon impacts on human Behavior.

  4. DC Whitehead, MD, FACEP

    The terms “ER” and “ER doctor” are over 50 years out of date. Emergency physicians practice in an emergency department (ED). “ER” means erectile ruination.

  5. Gioacchino aj Patuto, MD

    I def believe the full moon has a direct effect on Human Behavior.. I was a Dr. Without Borders for24 years and saw theeffect across the World in every Hospital and ER!!!

  6. Nanettte Ritchie

    I not only believed it before, but especially since I lived it. My first Neurology ER call at the VA was totally by myself on a Saturday night, Halloween and the height of a full moon. I can’t even describe the chaos. The regular “I am Jesus” patient in his white sheet robe preaching from atop the furniture started the evening and the next 8 hours were something to behold. Will never forget it. The backup attending who was absolutely brutal with neuro residents was a sweet, helpful pussy cat when I had to wake him up at 3AM. That was the only bright spot of the call – except for the moon shining through the hospital windows.

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