JOHANNA MAYER: Just a note. In this episode, we're going to be using terms like "madness," "lunacy," and "insanity." Not because we think they're great words, but because we'll be discussing some old and antiquated ideas about mental health, and these words reflect how people spoke about these issues historically. OK, here's the episode.

It was December 5, 2012. The US was just recovering from Hurricane Sandy and a grueling presidential election. And Congress was deadlocked over the federal budget.

And in the midst of this chaos, a bill landed on Barack Obama's desk. And it kind of slipped through the headlines unnoticed. It was called the 21st Century Language Act of 2012, just 287 words long. And it was meant to do one thing, remove a word from the federal code, the word "lunatic."

CHRIS EGUSA: See, up until that point, the word "lunatic" was still tucked away in different parts of the US law.

JOHANNA MAYER: Meet reporter and producer, Chris Egusa.

CHRIS EGUSA: You could find it in laws about banking, controlling estates, and others. And even though the bill Obama signed removed the word from the federal law books, it's actually still in use in some state and municipal laws.

JOHANNA MAYER: Which is pretty shocking. Imagine being in court and hearing a lawyer say stuff like this. Quote, "The words 'insane,' 'an insane person,' and 'lunatic' shall include every idiot, lunatic, insane person, and person non compos mentis." Yeah, not great.

CHRIS EGUSA: The word "lunatic" conjures up images of the notorious asylums of the 17th and 18th centuries, straightjackets and padded rooms. Its history goes back much further, though-- millennia back. The word "lunacy" comes from the Latin word for moon, "luna," and the Latin word "lunaticus," which essentially means moonstruck, because there was a time when we thought the power to change our moods and minds came from the sky.

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JOHANNA MAYER: From "Science Friday," this is "Science Diction." I'm Johanna Mayer.

CHRIS EGUSA: And I'm Chris Egusa. And today, we are talking about the word "lunacy."

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It's July of 2018. Miena Hall has just finished med school and is in her first year of residency. She's been working in the Labor and Delivery Department for the last month and is about to do her first 24-hour shift. And this shift starts off like any other. Miena arrives at work and picks two patients to follow, both mothers who had been induced into labor that morning. But then the cases begin piling up.

MIENA HALL: Another mother came in. She was already in labor.

CHRIS EGUSA: From there, it's nonstop. Miena delivers the first baby, then has to treat someone with chest pain. Runs back for another delivery, then a possible stroke. Finally, it's around 2:00 AM. She's about to rest, and then another woman in labor is wheeled into the department.

MIENA HALL: She's screaming, essentially, as she's getting wheeled to the labor room, saying like, "I need to push! I need to push! I need to push!"

CHRIS EGUSA: They get the mother to a hospital bed and boom, she delivers. When it's all over, Miena just slumps over. She says, on nights like these she's noticed a curious reaction among the medical staff.

MIENA HALL: It's just everything is happening all at once, and those are the nights when we'll say, someone look outside. See if it's a full moon.

CHRIS EGUSA: Because according to Miena's coworkers, full moons are when things get wild and the unexpected happens. And sometimes, someone will actually go check. The Labor and Delivery Department doesn't have a lot of windows.

MIENA HALL: One of the nurses will have to go into one of the empty patient rooms in order to actually look outside. And I didn't see whether it's a full moon or not.

JOHANNA MAYER: It was not. Turns out, that particular night, it was actually a new moon. But our belief in the connection between the Moon and strange behavior is a pervasive one.

[HOWL]

The inspiration for countless werewolf movies.

JACK GOODMAN: Beware the Moon, David.

JOHANNA MAYER: And it's an old one. Humans have been blaming the Moon for odd occurrences for a really long time. One area the Moon plays an especially big role, madness. To really understand, we have to go all the way back to the ancient world.

For millennia, people have lived their lives according to the movements of the night sky. The Egyptians looked to the star Sirius to predict the flooding of the Nile. For the Maya, the appearance of the planet Venus coincided with the rainy season. And the Babylonians pretty much invented astrology, which they used to explain all kinds of earthly happenings.

CHRIS EGUSA: And these celestial bodies came to hold great power in people's minds. And nowhere was that more apparent than the ancient Greeks, where a pantheon of gods and goddesses personified the cosmos. And ultimately, that shaped how they thought about mental health.

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Diseases affecting the brain or nervous system were thought to come from the gods. That's because their causes were unclear. It's not like someone getting injured in battle or breaking a leg. These conditions were mysterious, and so the source, the thinking went, must be equally mysterious. Enter the Moon.

For the Greeks, the Moon was a shadowy, mystical figure, a kind of bridge between the human world and the supernatural. And so while there were a lot of beliefs floating around at the time, the mystery of mental illness clearly gets connected to the mystery of the Moon. This sets the stage for all kinds of ideas about the Moon and its power over people.

As for the word "lunacy," its origins were probably based around epilepsy. Ancient Greeks called epilepsy the "sacred disease" because of its supposed supernatural origins. And they would attempt to invoke the Moon with magic rituals to cure it.

JOHANNA MAYER: And as time went on, the idea expanded beyond epilepsy to include all of mental illness. In the first century, the Roman naturalist Pliny the Elder wrote that the full moon caused the brain to get unnaturally moist, leading to both epileptic attacks and madness. In his view, much like a certain Franz Anton Mesmer would come to theorize centuries later, the Moon was acting on liquids in the body, the same way that it acted on water in the ocean, with the tides going in and out. Which has a kind of logic to it. I mean, humans are more than half water and the brain is one of the most watery parts.

And we see this moon madness idea pop up over and over again. You have Roman stories about the moon goddess Luna driving her enemies mad with hallucinations. In the early Christian Church, insanity gets blamed on demons who work under the cover of the Moon. And into the 1700s, in the infamous lunatic asylums, Moon phobia ran deep. One London doctor observed in his case notes that patients' lunacy would wax and wane with the cycles of the Moon. Some asylum patients would even be chained up and beaten during full moons.

CHRIS EGUSA: And as outdated as these ideas sound, it turns out the belief that the full moon can affect people's behavior is still alive and well today. In 2007, the town of Sussex in England began ramping up patrols of police officers during full Moons, citing expectations of increased violent crime. In 2014, a British politician claimed that surgeons wouldn't operate during a full moon because people bleed more.

And most surprising to me, a study in 2011 found that 40% of medical staff surveyed actually believe in the idea of a full moon effect. Remember Miena Hall, our doctor from the beginning? She says that for many of her colleagues, the full moon effect is no laughing matter.

Miena HALL: They're very superstitious, very superstitious. It kind of surprised me. But I think that's just part of being human. We try to look for patterns where there may or may not be any.

CHRIS EGUSA: So I got curious. Is that what's really going on here? I mean, this idea of the Moon affecting human behavior has been around for so long, and it seems to be so widespread. Is it all just sort of confirmation bias? Seeing patterns where none exist? So I started digging.

First, I learned that the whole lunar effect idea has been mostly debunked. Researchers have looked at overall hospital admission rates and found that admission did not increase during a full moon. And the idea that gravity could be moving the moisture in our bodies, very unlikely. A mosquito landing on your arm exhibits a stronger gravitational pull on you than the Moon does.

But some individual studies have shown odd effects. One study showed lower sleep quality in patients during a full moon. Another showed an increase in motorcycle accidents and an even higher number during a supermoon, the theory being that the sight of a big full moon is distracting.

But when researchers have done meta-analyses where they look at a whole lot of studies all at once, most of these effects disappear. And the whole idea of a lunar effect had pretty much been written off as pseudoscience. Then, in 2018, a study was published in the Journal of Translational psychiatry that had researchers scratching their heads.

JO MARCHANT: And that has really got a lot of scientists to sit up and take notice and say, well, something is going on here that we don't understand. Because it was a very robust and well-respected study.

CHRIS EGUSA: Jo Marchant is a science journalist and author of The Human Cosmos. So in the study, a researcher at the National Institute of Mental Health had looked at people with rapid-cycling bipolar disorder. He believed that their mood changes were being caused by the Moon.

JO MARCHANT: So in this study, these patients tracked the timing of their sleep and wake cycles and their mood switches over many years. And the study showed that the mood switches were triggered by varying sleep patterns, which were in turn linked to lunar cycles.

CHRIS EGUSA: The researcher hypothesized that the participants' sleep cycles had become uncoupled from the 24-hour clock, the solar day. And instead, had become fixed on the 24.8-hour lunar day. Every time there was a new moon every 29 and a half days, one patient would have a bout of insomnia and their mood would switch from depressed to manic or vice versa.

Since the study is so recent, there still isn't enough data to paint a clear picture of what's going on. For now, the evidence for a lunar effect on humans is far from conclusive. But when you look at research in the animal world, it's a whole different story.

JOHANNA MAYER: The field of chronobiology studies timing and rhythms in living creatures. It's a field that's long been focused on the Sun. But scientists are discovering that the Moon plays a critical role as well.

JO MARCHANT: So things like rabbitfish, bristleworms, coral-- and they're finding that in those species, actually hundreds of genes are also pulsing or varying in expression in time with the phases of the Moon.

JOHANNA MAYER: A honeybee's weight fluctuates and maxes out during a full moon. Oysters open their shells to feed according to the Moon's position in the sky. And coral in the Great Barrier Reef use the Moon to synchronize mass breeding events.

JO MARCHANT: They use both solar and lunar signals to time that to these really tight windows of just a few hours when all of these corals will be releasing eggs and sperm at the same time.

JOHANNA MAYER: And these are just a few of countless examples of life on Earth being plugged into the cosmic clock.

JO MARCHANT: If you're seeing that in so many widespread species of the animal kingdom in fish, coral, worms, these lunar clocks must date from very early in evolution. And so it wouldn't be that surprising if they do exist, in some sense, in humans as well.

CHRIS EGUSA: And for all the focus on the Moon and madness, one thing that stuck out to me is how much the Moon is actually a stabilizing force in our world. It literally stabilizes the Earth with its gravity. Without the Moon, the Earth would likely wobble on its axis by up to 10 degrees every 10,000 years, possibly alternating between plunging us into ice ages and horrible heat waves. And then it regulates the tides and rhythms of thousands of species throughout our world. And until very recently, humans were really dependent on the Moon, as it was the main source of light in the night sky.

JO MARCHANT: So in ancient times, it would have been central for every aspect of life. You've got this incredible view of the spectacular stars, the heavens, which most of us in cities now have forgotten even exist, that would have really blown people away.

CHRIS EGUSA: We've slowly been divorcing ourselves from the daily and monthly lunar cycles as we introduce more and more electric lights and device screens into our lives.

JO MARCHANT: And so we don't think about the sky. We're not thinking about those cycles that are happening, and we tend to think about ourselves as isolated, almost like machines, if you like.

CHRIS EGUSA: There's evidence suggesting that all this light pollution is affecting our mental health. But it's not so-called madness. It's anxiety and depression, driven by our increasingly dissonant relationship with the night sky.

And what of the Moon's direct effect on us? Can humans become moonstruck? Probably not in the way our ancestors meant it. But if we step back, the Moon's effect on humans is already obvious. It looms large in our popular imagination.

We are obsessed with it. We stare at it, write stories about it, it's in our songs, our conversations, our romantic gestures, our fears, and horror stories. A full moon can get our hearts pumping, because the gravity of its hold on our imaginations doesn't have to be mystical or measurable in a lab to be real.

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JOHANNA MAYER: This episode of "Science Diction" was produced by me, Johanna Mayer, and Chris Egusa. Elah Feder is our editor. Daniel Peterschmidt composed all the music and designed sound for this episode. Chris Wood mastered. We had fact checking by Danya AbdelHameid.

Special thanks to Andrew Scull, author of Madness in Civilization, Chiara Thumiger, who studies ancient medicine, and Janet Downie, Associate Professor of Classics at UNC-Chapel Hill. Nadja Oertelt is our chief content officer, and she recently attended a management training course and came back with this really intense attitude.

MIENA HALL: I need to push! I need to push! I need to push!

JOHANNA MAYER: See you next time. [LAUGHS]

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