Science Vs - The Full Moon: Is It Messing With Us?

Episode Date: October 2, 2025

People swear that weird stuff goes down on a full moon. In fact, even SERIOUS folks like the nerds who work in ERs will tell you that something is off about those nights. And what’s amazing is that science has actually looked at this. And … there is some weird stuff here! From animals to ERs to our circadian rhythms to our menstrual cycles, we’ll find out — is something afoot during a full moon? We talk to Emeritus Prof. of emergency medicine Dr. Wendy Coates and circadian rhythm researchers Prof. Horacio de la Iglesia, Prof. Kristin Teßmar-Raible, and Prof. Charlotte Helfrich-Förster.  Find our transcript here: https://bit.ly/ScienceVsFullMoon  In this episode, we cover: (00:00) What do people think the full moon is doing to us? (03:54) How the moon influences animals (07:47) Does the full moon make ERs busier? (15:09) Does the full moon affect our sleep? (22:11) HOW is the full moon messing with us? (31:05) Does the full moon affect our menstrual cycles? This episode was produced by Meryl Horn, with help from Wendy Zukerman, Rose Rimler, Michelle Dang, and Ekedi Fausther-Keeys. We’re edited by Blythe Terrell. Mix and sound design by Bumi Hidaka. Fact checking by Marlowe Starling. Music written by Bumi Hidaka, Bobby Lord, Emma Munger, So Wylie, and Peter Leonard. Thanks to all the researchers we spoke to for this episode, including Dr. Ron Flick, Dr. Michael Smolensky, Michael Bevington, Dr. Laurel Symes, Professor Laura Prugh, and Dr. Maarten Nijsten. Special thanks to Kevin Walsh and all the folks who chatted with me about the full moon.  Science Vs is a Spotify Studios Original. Listen for free on Spotify or wherever you get your podcasts. Follow us and tap the bell for episode notifications. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hi, I'm Wendy Zuckerman, and you're listening to Science Burses. This is the show that pits facts against the full moon. Does it change who we are? This episode about the full moon has been one of our most requested episodes this past year. You asked for it, so here it is. And to start our journey, we sent senior producer Merrill Horace. out to brave the streets of New York City. Picture it.

There's a chill in the air. Out in the east, the full moon was on the rise. And she ventured into a park to hear firsthand what people experience when there's a full moon. Makes people wild. It makes them carnal. It's a carnal thing happening. Everyone does not act right.

It's terrible. I think people are just whiling out. Clause out, you know. I'm blaming the moon. That damn moon. Some people said that the full moon stirred up all this drama in their lives. One guy said that sometimes he doesn't even go out when there's a full moon. I'm going to stay in that night, I'm going to play it safe,

just like because I know I could feel weird or do crazy stuff. Folks said you just knew it was going to be a full moon that night because people at work would be going bonkers. And this is in the research too. It shows that some health care workers think the full moon makes their patients behave stranger. One survey even showed that some doctors and nurses think they should get full moon hazard pay.

Meryl heard about this as well at the park. My mom was a nurse at the state hospital and she had a lot of psychiatric patients and she was like, oh man, the full moon is the worst. It's the absolute worst because people do act crazy. I've worked in retail. I worked there for like a full year every single time on the full moon. We had the craziest customers, and I would tell everyone, I'd be like, it's the full moon.

Watch out, and they'd be like, it's not going to be that bad of a day. It was. It was the worst days, every single day. You still work there? No, I quit. I quit on the full moon, actually. Like, fully quit on the full moon. And perhaps the creepiest thing of all, people said that the full moon could make blood come out of your vagina.

I mean, they didn't put it quite like that. It definitely affects me from like the feminine cycle, the monthly cycle. Do you think you sync up with the full moon? Yeah, for sure. My period will probably be coming because it's usually cycled with the moon. Literally, I go to beauty school, I go to cosmetology school, it's mostly women. All their cycles synced up to this week, basically. So up to the full moon.

So like they're in the middle of their periods, literally today. So could the moon be affecting our body and our behavior in these strange ways? While this idea might sound like it belongs in the world of horoscopes, perhaps even fairy tales, some scientists have been taking it very seriously. And in the past few years in particular, there's been a slew of peer-reviewed scientific papers coming out and claiming that the moon really can affect our bodies in very surprising ways. So in today's episode, we are going to look at this kind of. cutting edge science.

And by the end of the app, you might just be feeling a little carnal yourself. For hundreds of years, we've blamed all sorts of stuff on the... That damn moon. But then, there's science. Science versus the full moon is coming up after the break. You get access to exclusive dining experiences and an annual travel credit.

So the best tapas in town might be in a new town altogether. That's the powerful backing of Amex. Terms and conditions apply. Learn more at Amex.ca.com. This episode is brought to you by Peloton, a new era of fitness is here. Introducing the new Peloton Cross Training Tread Plus, powered by Peloton IQ, built for breakthroughs with personalized workout plans, real-time insights, and endless

ways to move. Lift with confidence, while Peloton IQ counts reps, corrects form, and tracks your progress. Let yourself run, lift, flow, and go. Explore the new Peloton Cross Training Tread Plus at OnePeloton.ca. Welcome back today on the show. We're looking at the full moon. There's one coming up on Monday. And so we're asking,

can it really influence us, change our behavior? And fellow lunar explorer, Merrill Haunt, is here. Hi, Wendy. Okay, so first up, can we just get a bit of a lay of the land? And could you just explain why do you see a full moon or a half moon or whatever? but why does it change? Yes, I can explain this. I actually brought a prop.

Ooh, great. Okay, so I have like a model of the sun, the earth, and the moon for you. Oh, my God, you've really gone all out, Meryl. Okay, so we are right now on the surface of the earth, right? Yeah, that I know. Yes. So imagine you're spinning around and around. The earth is moving around and around.

And when we are on the part of the Earth that's facing away from the sun, that's what we call nighttime, right? Right, yes. Well, the moon also has a side that's lit up and a side that's dark. And we see different amounts of that lit up side depending on where the moon is in its orbit around the sun. So when we see a full moon, it's when the moon is in this really particular position where you've got the moon on one. one side of the earth, and then the sun, like, on the other side. So it's almost like the sun and the moon are making an earth sandwich. Okay. And the earth is in the middle. It's the meat cheese of the sandwich. Yeah. And so the new moon, when the moon looks dark, is when it's in a

different position. So in that case, the moon is like the meat of the sandwich, and the earth and the sun are the bread. Okay, so could it, could just that fact that the billiard balls up in space are in this arrangement affect our behavior? I mean, it feels like maybe far-fetched at first, but if you think about it, we know that the moon affects other animals. That's right. And, you know, it's funny, the one thing that everybody associates with the full moon, wolves howling, I actually couldn't find any of, evidence backing that up at all? Oh, okay. But what I do have for you is that coyotes will howl more together on a new moon night. That's what they sound like? Yeah, kind of even creepier,

right? Like, there are these coyotes that will like yip together in groups at the darkest time of the month. Some owls will call out more when the moon is darker and badgers will pee more on stuff during a new moon. But what about, wait, who's affected by the full moon? I'm getting there. Well, the episode is called full moon, not new moon. All right, and then on full moon, some birds will hatch more around a full moon. There's a little worm that does a mating dance that happens just after a full moon.

Corals release their spawns a few nights after a full moon, which is an incredible event that you can see from space. and some primates, like nocturnal ones, will eat more during full moons. And I even found this one reference from the 1800s where a scientist said that rhesus monkeys were at their most fertile during full moons. So there are like all these ways that the moon is affecting animals. Now we're cooking with the rhesus monkeys. We're in primate land. I feel a kinship. All right.

But what about humid owls? animals. Merrill, are we affected by the moon? And why don't we start with the idea that on a full moon hospitals get packed, patients are going wild? Yeah, yeah. So researchers have actually looked into this. So there is, you know, the thinking is that if the full moon really is making people act more recklessly, then maybe we'll like see evidence for that and how busy ERs are. And I mean, there is just a long history of people thinking that this kind of thing is true. You can see it in our language, like the word lunatic that comes from the moon. Right. And so to find out if this is real, I talked to another Wendy, Wendy Coates. Is that going to be

confusing for you? No, it'll make me feel right at home. So what does expert Wendy say? Well, she's been an emergency medicine physician for over three decades, and she published one of the first studies on this question of whether ERs are more busy on full moons. Okay. It can came out a few decades ago. Great. So I got in touch. You reached out right around the time of the Blood Moon that was receiving so much popular press attention here.

And every time there's something about the full moon, I kind of remember sort of nostalgically back to this study. And then the next day, I opened my email, and you're like, Hi, I'm Merrill. Whoa. Tell us the story of Wendy's study. So it all started when she was just an intern at a major trauma center in Pittsburgh, and she said that pretty quickly she started hearing about this idea that things might get busier when there's a full moon. Okay, so you have to picture a bunch of emergency physicians and emergency nurses sitting around, well, we don't really sit around, but, you know, like in passing or, you know, you're sitting down to do your charting, and somebody says, get,

ready. It's a full moon tonight. What did they mean? Oh, we're going to have all these terrible accidents or, you know, you just can't even imagine. Here I am like a lowly intern and like all of these super experienced emergency department nurses and physicians are like gearing up for just like this intense night shift. And so I was like, okay, well, this must be something. Yep, youep, beep, beep, beep, beep. Are you the coyote? Yeah. Well, everything inside of me wanted to go, oh, and then I realized that's no longer factually acceptable.

But those are during a new mood. We have to rebrand the coyote. Oh, fuck, that's very new moot. Corals don't make any noise. Okay, so Wendy, all her superiors believe this to be true. What happens next? Well, so then she decides to do like a proper study on this. So here's what they did. She worked with her advisor and they got the records from her trauma center for a year. Over 1,400 people altogether. And she looked to see like how many people were admitted, how bad are people's injuries, whether or not they died. And then they took the day of the full moon and also the day before that and the day after it to kind of look at all those nights around the full moon. And then compare those. those nights to every other night of the month to see like, okay, is there any difference here?

Was this night different to all of the nights? Yeah. Yeah, here's what she saw. It was pretty funny because we're like, hmm, it looks like there's no difference. Oh, no difference. Yeah, there was no increase in how many people were admitted, how bad their traumas were, or how many of these patients died around the full moon. And in fact, well, maybe there are fewer traumas and less severe traumas on the actual full moon days than the other days.

Less severe traumas, she said. Yeah, a little bit, which she thought about it and was like, oh, maybe this makes sense because on those nights. It's brighter. So maybe it's easier to drive on dark country. roads where lots of motor vehicle accidents occur, maybe you're not quite as likely to go stab somebody because you'd be more visible to more eyewitnesses. And since Wendy's study, others have come out looking at the same thing across the world. Like a couple studies from the Netherlands did see a tiny decrease in traumas on a full moon.

Decrease again. Yeah, yeah, it was like better. Okay. And overall, a review of these studies said that there's no increase in how busy emergency departments are during a full moon. All right. So Wendy, does she worry when there's a full moon these days? No. Yeah, I asked her because she actually still works in an ER. Now, when you hear people mention this idea that, oh, it's a full moon tonight. Get ready.

Do you say anything? Nope. No. I never do because, you know, like, you don't want to be that person. And you're like, actually, we studied this and we found that blah-bidi-blabity-blab-de-blah. Like, you just don't want to be that person. Do you know, I feel like this will really land the point, hashtag not all Wendy's, you know? Or not well, actually Wendy's.

Yeah. Some of us are well-actually Wendy's. Some of us are not. And Wendy had this really lovely theory as to like why this idea sticks around the ER despite the lack of evidence. You know, like if you have a group of people and they're united against some sort of assault, so, you know, you're going to have this night that's crazy, busy, you're not going to get to eat, you're not going to get to go to the bathroom. But yeah, we can all unite on the reason.

Yeah. And just like, yeah, yeah. It's like bonding. It's bonding time and we can't predict who's coming. We can't predict how busy it's going to be. But what we can predict is that we're all there for each other and that sometimes something like talking about a full moon or the little look you give up to the sky as you're walking past one another gives you a little bit more encouragement to help you do your job well

and be together with your team to take care of all the patients. who come in. It's not nice. It is nice. If only we could all be united by the full moon. Yeah. So where do we go to here? Okay.

Well, so, yeah, it doesn't seem like the full moon makes ER is busier. By the way, I also looked into this idea that there's more crime on a full moon. A couple studies looked at that and did not see anything there either. Okay. But Wendy, this does not put the kibosh on the whole idea that the moon can affect our behavior. Actually, after doing all of this research, I am more of a true believer. Merrill Haunt never thought I'd see the day. Merle-Hon PhD. I know. What did you find? Okay, so there's this one super interesting study that I want to tell you about. Okay.

All right, so it was done by Professor Orasio de la Inglacia at the University of Washington and Seattle. Have you ever howled at the moon? Not really, not yet. But maybe, you know, if I keep doing research on it, I might end up doing that. Well, I think if he keeps doing research on it, he'll know that that's a myth, Merrill. That's true. So he's done field work in Argentina, where he's from, with a group of indigenous people, the Tobacombe, who are living in a really remote area with no electricity. And he was curious whether living in these conditions, the moon.

might be affecting their sleep. The sleep? Yeah. Essentially, they live very much in tune with the natural daylight and the natural light-dark cycle. So there is no street lights, no... No, no street lights, no lights in the houses. So he asks people to wear a device on their wrist, sort of like a fit bit, but fancier, that tracks their sleep. 25 people agreed to do this.

And then he, like, plotted out all of this sleep data next to the, like, lunar cycle to see if there were any patterns. So if on a full moon people slept more or less? Yeah. And he did see that on the days leading up to a full moon, people were sleeping less. People were going to bed much later, up to an hour later, and sleeping by about an hour less. Huh. That's a pretty big effect. Yeah, that's a huge effect in sleep terms, right?

On average, it was about a 45-minute difference. And Erasio thought that it was probably the brightness of the moon that was doing this. Yeah, right. Particularly for this community. We don't realize how bright the moon is, particularly when you are under totally natural light conditions, right? Because suddenly, the sunset, it gets very dark. and if the moon happens to come up just before, you know, you're about to go to bed, it's nearly impossible to go to bed, right?

You see the moon there. It's that bright out there. Exactly. You know, you could even read under full moonlight. Oh, wow. So then Horacio decides to look at places that weren't rural, like cities. He starts with a group of Tobacom people who are living in a more urban area. Okay.

And weirdly, he found that their sleep was still affected by the moon. So now Oresio is like, okay, let's run the experiment again where he lives in the U.S. in Seattle and Washington State. He gets sleep data from about 120 people there, mostly young adults, and he still sees the same pattern. So these people living in Seattle were also sleeping. on the nights leading up to a full moon by like 20 to 40 minutes. And so now he's sure it's not the brightness of the moon anymore. Well, yeah, because it's a Seattle. Like, it's cloudy most of the time in the winter there.

And Horatio is still seeing this pattern, even in the winter. And then the moonlight is also competing with other forms of light in a city. Like, apparently the moon, even when it's full, is still something like 50 times less bright than a single street light. The fact is that we see very clear lunar rhythms in people living in a place where light pollution is way above the intensity of full moon nights, and we cannot explain that by moonlight.

So what's going on? Was it just that they were partying more on a full moon? Yeah, you mean like going to like full moon parties? I guess so. Well, you know, sitting out in the park. park, watch the full moon. I don't think so, because when you look at the data, it's not like people were like suddenly sleeping less just on the night where there is a full moon. What you actually see is this pattern where you kind of like sleep less and less gradually in the days

leading up to the full moon. And then it kind of peaks. And then you start sleeping more and more and more. And then the full moon happens and you keep sleeping more and more and kind of goes like up and down, up and down in this like wave pattern. And Horacio saw this across all his data. By now, I have no doubt that there's a lunar month modulation of sleep, particularly when you see single people doing this beautiful sinusoidal oscillation in their sleep. Would you want to see the wave pattern?

Yeah. Oh, yeah. Yeah, there's a very nice wave pattern there. Very intriguing. Huh. It's a beautiful sinusoidal pattern. It is a beautiful sinusoidal pattern. So, yeah, it really doesn't feel like you could, like,

create that pattern of sleep, even if you tried, right? It's not like people party a little bit more. Yeah. And if the moon affects our sleep, then that kind of opens the door to it may be affecting us in other ways, too, because we know that sleep can affect our mood and our mental health. Uh-huh. And in fact, like, there are actually studies on bipolar disorder, specifically this thing called rapid cycling bipolar disorder.

And what the researchers are seeing there is that these patients seem to, like, be switching between mania and depression in a timing that kind of lines up with the cycles of the moon. And those researchers also think this could be related to sleep. Like, maybe if you're losing sleep around the full moon, it might kind of trigger a manic state. What? And so now Horacio and some other scientists believe that, like, yeah, it does seem like the moon is doing something strange here, that it's, like, somehow changing our bodies and our brains and affecting our sleep. And it's not just about how bright it is or partying more or whatever. It's like there's something else. What, though? How is it doing it?

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Disney Plus. Welcome back. Merrill has promised to tell us why the lunar cycles might be getting into our body and somehow affecting our sleep. I don't know. What's going on here, Merrill? This is strange. Well, I mean, this is where things get exciting, right? Because now we have this thing that the moon is doing to us, and we just need to figure out how.

Mm-hmm. And, you know, when I talk to people on the streets about this, about how the full moon could be affecting us, they had all sorts of ideas. I definitely think this is an energy thing. It's because all of us are really here in a sea of energy. It's that energy. I feel like energy, like different types of energy, like that you, I don't know. I feel like it is. We're made of, like, 70% water and, like, the moon controls a tide.

So it would make sense that it has an effect on us, too. Humans are 70% water, so the moon is going to automatically influence us if we are water. Its alts are actually only like 55% water. But anyway, let's look at this, because like the general idea is that we know the moon creates tides in the oceans through like the pull of its gravity on water. So what if it's doing something similar to us? Right. Okay. And is there any evidence for that? Well, first my question actually was just like, okay, sure. It's like pulling on us a little bit, but like, how much?

Like, is it realistic that it's a big enough force to do anything? So I asked an astronomer and a title expert, and they didn't, like, laugh it off completely, but they did the calculations on, like, how big the forces were, and they were tiny, like, minuscule. One of them found that the force of the moon's gravity on our bodies is less than if you were just, like, walking by a tall building. Like that building next to you would have a bigger force on our bodies than the moon, because it's like a lot closer. Yes. Okay. But still, like, just because the force is small doesn't mean that it's not doing anything to anybody.

Like, I wondered if we knew of any animal that can sense this, this pole from the moon and thought of the animals that, like, live in the title zone. Because those animals are really affected by the moon's gravitational pull. How big the tides are has this huge impact on their day-to-day life. Right. And so how are they detecting those changes? Is it just, you know, through the water or gravitational changes directly from the moon? Yeah. So to find out, I called Professor Christian Tesmer Reble at the University of Vienna and Austria,

since she wrote a review about how animals are affected by the moon in different ways. Right. So I asked her, do we know of any organism that can directly sense the changes from the moon's gravity? Oh, I don't know. No. Who uses it? I mean, you mean, not obviously tidal changes. Not being jostled by the tides, yeah, but like directly sensing the moon's gravity.

sensing it. I am not aware of something like this. So, yeah, the case for gravity, I'd say, is pretty weak. Much like the gravitational force of the moon on us. Yeah, exactly. Okay, so it's probably not gravity. What else is there? Well, there's one other thing. So the Earth has this super cool magnetic field around it. And as the Moon revolves around the Earth, it seems to, like, mess with this field. And we do know that some animals can sense the Earth's magnetic field. We know organisms like migratory birds that use that for their long distance flights. And it's not, and it's actually not only birds, also butterflies sense the magnetic field, right? And the way we think that they're doing this is through this protein called cryptochrome.

Uh-huh. Sounds like something I should have invested in. 10 years ago. What is it? Okay. So, yeah, cryptochrome is a protein in our bodies that can interact with the magnetic fields. And it seems to be helping the birds know which direction to fly. Uh-huh. And do humans have cryptochrome?

We do. We do have a version of cryptochrome. It's not the exact same protein that the birds have. But we actually do have a little evidence that. our cryptochrome can sense the magnetic fields too. And so maybe that's how the moon's affecting us. Because, like, okay, what we would be looking for if, you know, the Earth's magnetic field is the missing link. Right.

Maybe it should have a similar kind of wave pattern, like that sinusoidal curve that we saw in Horatio's leap data. And then I stumbled on this graph where I was like, whoa. All right. Let me show this to you. Show me the whoa graph. Is it a cytosoidal again? Because I don't know if I could handle that, Merrill. I don't know if I can handle it.

So scroll down in the search. Whoa! Is it sinusoidal? Is it sinusoid? Yeah. If you didn't think you were listening to a nerdy podcast, you do now. That is, okay. So what is, what is this magnetic field?

Yeah, this is the change in magnetic fields over a lunar cycle. So the line in the middle is the full moon. The magnetic field is apparently lower in the days leading up to a full moon, just like Rossi was off. And then it gets like higher after the full moon. But I don't know if I've gone off the deep end. Like this paper is, you know, it's from like the 1960s. Yeah.

It's hand drawn. It's hand drawn. That's for sure. Like someone used a ruler to make those lines. Okay, so what this shows us is that the moon affects the magnetic field in this sinusoidal pattern that is similar to the way that the moon seems to affect our sleep. Step one. But then step two, has anyone figured out if the cryptochrome is,

in us is actually detecting those changes to the magnetic field and that that is then affecting our sleep? No, like nobody's actually like connected all the dots here to find out, okay, can we really sense the magnetic fields at all? And can that mess with their sleep? When Kristen was explaining this to me, there was lots of like hand waving going on and like emphasis that it's like all kind of just theoretical. So it's really unclear still.

But this is a lot of wild speculation I have to emphasize. Yeah, she said that this question of whether the moon is having like a subconscious effects on us is at the frontiers of our knowledge. It's like a black hole. But that doesn't mean that it's impossible or like a silly idea. Just because it is a subconscious. phenomenon, it doesn't mean that it doesn't exist, right? I think people tend to say, oh, I cannot feel it, and therefore it doesn't exist. But we usually don't feel our liver, at least hopefully

not, but it's very existing, right? Yeah. He's doing all sorts of stuff to us. Exactly, exactly. So, I mean, the fact that we are not consciously aware of something is true for a lot of our physiology. Do you think that the moon for sure is influencing people? I think yes. The reason why I think yes is that I'm a biologist. For me as a biologist, humans are just another type of animal. We're made of the same stuff as the worms. Exactly. At the end, exactly, like this, with some few specifications that are a bit different. From the larger perspective, it's martial. So, Okay, so here is where we are at. The cycles of the moon do seem to affect our sleep.

Somehow, we're not sure how. Last question, can it affect blood coming out of our vaginas? You mean our menstrual cycles? Yes. Yeah, let's look at that. It comes up all the time. I've heard from a lot of people who think there's something. there. So, yeah, I called up a scientist who did a pretty wild study on this.

Do you not describing a period-based study as a wild study is immediately making me think of just a scientist throwing around dirty tampons for some reason? I don't know why. I mean, it doesn't go that carnal, but it's, you know, as well as it is. It's own way. All right, let me tell you about it. Okay, okay. So the idea first came to her when she had this commute where she was walking a lot at night.

I was walking from the train station to my home, family home. And what did it look like on a night when there was a moon? Oh, fantastic, because you could see everything. You don't need lights in the street. So I always loved the moon to be out. This is Charlotte Helfrieck Forster, senior professor at the University of Würzberg in Germany, and she noticed something about her period around this time. My first day of menstruate was always around the full moon.

And when I was really astonished, oh, that's interesting. Do you know, Merrill, I'm the exact opposite, that my, I will ovulate around a full moon and get my period, I guess, in a new moon. But I just assumed it was because I'm a pretty regular cycle and that's just what a month is, you know, around 28 days or whatever. Sure, but like if you think about it, even that's pretty weird, right? Like that for a lot of us, our periods just happen to be 29 days long, which is the same length as the lunar cycle.

I guess so, right. Yeah, why are our cycles the same as? the cycles of the moon. Okay, yeah. I mean, yeah, it could just be a coincidence, but maybe something else is going on here. And so, like, for Charlotta, she started wondering,

how long have I been getting my periods at the full moon? Right. And luckily enough, she had actually been keeping track of when she was getting her period for basically her entire life. Wow. Like she started when she first started getting her period.

My mother told me to make always a cross in my calendar at the first day of my mantis. So I did it without thinking. And kept all these little calendars at her home in a cabinet. And so now she went back to check, like, has this always been a thing for me? Amazing. And just by eye, she could tell that, like, oh, yeah, for like many years of my life, I've either been synced with the full moon or sometimes it was the new moon.

And so she starts wondering, all right, how many people is this, like, true for? So she asks her mom and her sister if they kept their calendars and they did. And she looked at their data and saw similar stuff. But of course, as a scientist, you know that three examples are not enough. And then I started to ask colleagues, friends, whether they by chance had kept any recordings of her mantis. And so it took her about 10 years to collect this data from 22 women who had kept track of their cycles for an average of 15 years. years of their life. Wow. Okay. And so now we can find out, do people, on average, get their periods more often around the time of a full moon? Great. So what did she find? She saw that, yeah,

there was something there. So in this group of 22 women, they were more likely to start their periods, either around the time of a full moon, like especially the days leading up to a full moon or the new moon. Oh. How curious. But like I'm one of these people who does not think this is true for me. So I asked how strong of an effect was it? Since I was curious, I looked at my data for the past few months and it definitely was not sinking to the full moon. That is very important. The effect is really very small. And to be honest, when you look at your entire cycle, it's only a small part during a cycle that is synchronous to the moon. So, yeah, I mean, obviously it's not like everyone's getting their periods on the full moon.

Yeah, right. It's more like it upped your chances a little bit that you'd get your period on either a full moon or a new moon. Okay. Uh-huh. But there's something else that I need to tell you about her study. So after it came out in 2021, all these other women start sending sure a lot of their calendars. They're like when they got their period. So then she got data from more than 100 other people,

and she tried crunching the numbers again, and here's what happened. I was absolutely disappointed. When I pulled all the data, the new data that I had, I didn't see any synchronization to the moon anymore. So it was very different from my first study with the 22 women. Ah, that classic thing where you study something in a few people, get a very exciting result. and then you study it in more and more people

and realize it's not generalizable. We've seen this countless times before. Charlotte and I are the anecdote in the room that gets the headlines. Okay. I mean, Charlotte still thinks there could be something here. Like, she's been looking into whether light pollution is a factor. But she also pointed me to some other data.

Like, okay, so there is an analysis that came out recently from a Purian tracking. app and it looked at seven and a half million cycles and they didn't see any sinking to the moon whatsoever. This has actually made me feel more like a witch, you know, because obviously we couldn't. Because it's so rare. Yeah, we couldn't all be witches, you know. Well, I'm glad you feel special now. That's what I'm here for. But I guess we're all a bit witchy because the moon is affecting all of our sleep in this mysterious way. Don't patronize me just because I have sleep still.

I don't feel like a witch. It's okay. Do you think that the moon is affecting you? I really love the moon. I love a big fall moon. I like looking at it. I like thinking how small I am in this big universe reminds me of that. I love when you see it rising and it's just huge.

I love it for all those reasons. I don't know if it's having some deeper subconscious effect on my body. What about you, Meryl? You've been researching this for a while. Has it changed your view of the moon? Yeah, I think it, I don't know, I feel like now I am less skeptical. Like when I was in the park and everybody was telling me about how they felt like the moon was just changing the energy and like they could feel it and that they knew there was like something there.

I was just like rolling my eyes and like, sure, it's like changing the energy. But now I'm like, oh, actually maybe it is. It's the magnetic fields which is like a kind of energy. It's just so mysterious. There is an effect, at least on our sleep, that we don't understand yet. I feel like I'm more humble now about what's possible with our bodies and the moon. Do you want to yip with me? Yip, yip, yip, yip, yip, yip, yip, yip, yip.

Thanks, Wendie. All right, Merrill, how many citations in this week's episode? This week we have 52 citations. And if you go to our show notes, you can find links to the transcripts, where you can see all of them and read more about the moon. Excellent. If you want to tell us what you thought of this episode, we'd love to hear from you. We are at Science underscore VS on Instagram. I'm at TikTok at Wendy Zook. Thanks, Merrill. Have a happy full moon.

Oh, yeah. Be careful. This episode was produced by me, Merrill Horne, with help from Wendy Zuckerman, Rose Rimler, Michelle Dang and Akheti Foster Keys. We're edited by Blythe Sorrell, mixed and sound design by Bumi Hedaka. Fact-checking by Marlowe Starling. Music written by Bumi Hedaca, Bobby Lord, Emma Munger,

So Wiley, and Peter Leonard. Thanks to all the researchers we spoke to for this episode, including Dr. Ron Flick, Dr. Michael Smolenski, Michael Bevington, Dr. Laurel Sims, Professor Laura Prue, and Dr. Martin Nyston.

Special thanks to Kevin Walsh and all the folks who chatted with me about the full moon. Science Verses is a Spotify studio's original. Listen for free on Spotify or wherever you get your podcasts. And if you do listen on Spotify,

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