That Neuroscience Guy - The Neuroscience of Melatonin

Episode Date: May 20, 2026

The title name says it all!

So this episode might seem a bit weird. First of all, there isn't going to be the traditional bump. Matt's taking a bit of time off, so you're just going to get me raw. I'll warn you right now, there's going to be some goose and some gaffs. This is what it's like if you take a class from Dr. Krig Olsen. And with that, away we go. Hi, my name is Olaf Kig Olsen, and I'm a neuroscientist at the University of Victoria. and in my spare time, I'm that neuroscience guy.

Welcome to the podcast. Have you ever laying in bed completely exhausted and still not being able to fall asleep? You turn off the lights, you put your phone away, you close your eyes, and your brain suddenly decides this is the perfect moment to replay an awkward conversation from eight years ago.

Or, you know, something that happened to you recently that upset you, or even something that you really were into. Or maybe you fall asleep just fine, but wake up at three in the morning, staring at the ceiling, fully awake for no obvious reason. I'll be honest, that happens to me all the time, which is why I wanted to use that example.

For some people, a solution seems simple. A tiny gummy, a small white tablet, a supplement sitting beside the bed labeled melatonin. you take this people say your brain will finally sleep but what exactly is melatonin is it a sleeping pill a hormone a brain signal why does it help some people dramatically while others say it gives them vivid dreams or even nightmares so on today's podcast the neuroscience of melatonin and i'll have to admit, this inspired me because I've stayed away from sleeping supplements, but I've recently been trying melatonin out, and I thought I'd do a deep dive into it and see what's really going on.

So what's melatonin actually doing inside the brain? We're going to explore the neuroscience of melatonin. What it is, how it works, why people use it, where it can help and where things become more complicated than most people realize. So let's start with the basics. Melaton is not technically a sedative. It's not an anesthesia. It's not like alcohol. It's not a knock-you-out chemical.

Melaton actually is a timing signal. Your brain uses it naturally to help regulate when your body believes it's supposed to go to sleep. So to understand this, we need to talk about the circadian rhythm, and we've talked about it before, but let's just do a quick. quick review. The circadian rhythm is your brain's internal clock. It is a roughly 24-hour timing system, and it coordinates sleep, alertness, hormone release, metabolism, body temperature, and even brain performance. Now deep inside your brain, there's a tiny little structure

called a superchaasmic nucleus, often shortened to SCN, and that's why we do this in neuroscience, just so you know, we use the abbreviations, because a lot of these things, even I, with 25 plus years of doing this, have trouble pronouncing. So if you do, don't feel bad. Anyway, the SCN sits in the hypothalamus and it acts as the master clock of the brain. So basically, its job is to synchronize your body with the outside world. And the most important thing it uses to synchronize is light. So when light enters your eyes, especially blue wavelength light, and that's where all the blue wavelength stuff comes from, signals travel from the retina to the SCN. The SCN tells the brain, you know, it's daytime. Stay alert. Stay awake. Now as evening approaches and light decreases, the SCN begins shifting the brain towards nighttime physiology.

And that's where melatonin leaps in. Melatonin is produced primarily by the pineal gland. It's a small little structure near the center of the brain. You may have heard of it. As darkness increases, melatonin production rises. This is something I want to emphasize. Most people don't realize this. Your brain produces melatonin naturally.

All right? It's not, yes, you can take it externally, but it's something you produce naturally. Now, just the release of melatonin doesn't necessarily force sleep. It's just telling the brain it's nighttime now, so it's setting you up for sleep. And that's an important distinction to make. It really is, because melatonin is more like setting the stage for sleep than flipping an off switch. And this is why melatonin helps some sleep problems more than others. For example, melatonin can be especially useful when the timing is.

asleep is disrupted. Jet lag is a classic example and it's when I've used melatonin in the past. You fly from Canada to Europe. Your body clock thinks it's still in Vancouver while the outside world is operating on Paris time. So what melatonin can do is help shift the timing of the circadian rhythm so the brain adapts more quickly to the new environment. Without it, it will happen naturally. I'm not saying you have to take melatonin. It's not saying you have to take melatonin. It's just something that people try to use to promote that shift. Now, this same principle applies to shift workers, delayed sleep phase syndrome,

where people whose sleep schedules differ later and later over time. So in these situations, you know, melatonin can almost act like a biological reset queue. When the brain processes it, it goes, oh, hang on, it's time to get ready for bed. But this is where the misconceptions happen, and it's important to really understand that. Many people treat melatonin like it's a sleeping pill, which it isn't. They take larger and larger doses expecting stronger sedation.

But the neuroscience is pretty clear here. More is not always better. In fact, some researchers believe modern over-the-counter melatonin supplements, they're overdosed. People are taking too much. So your brain naturally releases melatonin extremely tiny amounts. And just this more or better idea, I really want to emphasize this. It's not a true thing.

Taking more melatonin isn't going to help you sleep more, all right, or help you fall asleep more quickly. And the actual measurements we're talking about here are picograms and nanograms. All right, a picogram and a nanogram. the size of that. Yet if you go to the grocery store and buy this stuff, you can get five milligram pills, 10 milligram pills, or even 20 milligram pills. You know, that orders of magnitude above what the brain produces naturally. So it's actually better to take a lower dose. At least that's what the research suggests. It does suggest that taking too much melatonin is a bad idea. So if you're trying to get your clock sorted, you're better to take a smaller dose of melatonin. And just remember,

it's a signaling molecule. I want to keep coming back to that. It's not what makes you fall asleep. It's what tells the brain it's time to get ready to sleep. So the goal of taking it is to mimic or reinforce that system, but not overwhelm it, which is why that 20 milligram pill is completely nuts. Now, this does lead us to an important question. If melatonin is already naturally produced by the brain, why do some people produce too little? Now, the answer varies. Age is a big factor. Melatonin typically declines with aging, which is why older adults may have trouble sleeping. Light exposure is a big one. In the modern world, you're just filled with artificial light, all right? You know, I remember teaching high school in England a long time ago,

and I remember starting teaching when it was dark and ending teaching when it was dark, that will mess up the melatonin cycle. Phones, tablets, LEDs, laptop screens, all of that blue light exposure at night can suppress melatonin release. This is probably the biggest problem with these things. One is the refresh rate, but the other is just the blue light, which is telling the brain, no, no, no, no, it's not bedtime. and that's going to interrupt the brain's natural release of melatonin.

Now, from the brain's perspective, you know, if you say this bright light at 11 p.m., it's thinking, well, I'm not 100% sure what's going on, so it won't work the way it's supposed to. Because the SCN, the super chasmatic nucleus, it's receiving conflicting information. Your schedule may say bedtime, but your visual system says morning. And this is one reason why sleep researchers often emphasize sleep hygiene as opposed to something like melatonin. Reducing evening light exposure, especially blue light, can help you fall asleep. Now, one thing that fascinates people like me about melatonin, even though I'm trying it, I feel like a hypocrite. I'm not going to lie.

But just how deeply interconnected sleep is, like I really think of it. about that with every brain system. And you've heard me say this on this very podcast. I firmly believe that sleep is the single biggest predictor of brain health, more than anything else. So as sleep quality goes down, cognition, all of those cognitive systems fall apart, attention, working memory, emotional regulation, decision making, reward processing. So sleep deprived brains often become more impulsive and more reactive emotionally. The amygdala, it's almost like we can't go an episode without the amygdala, but that's the brain region we talk about all the time with emotional salience threat detection and just about everything else. It is more reactive under conditions of sleep

deprivation. And prefrontal systems start to shut down. So the prefrontal cortex, our old friend system two, it starts to shut down as well. So when people go out for melatonin, they're not just seeking sleep. You know, you could argue that people are looking for restoration. They want their brain back, right? They want their brain to function normally. And it's really about improving sleep timing. So if you get to sleep and you're able to sleep, guess what? Cognition's better, mood's better, overall well-being. Melatonin is not the only cure for this. And I tell you you should actually try sleep hygiene.

I'm doing this as a bit of an experiment, not trying to get out of jail. But I'm a big proponent of sleep hygiene, and that's usually where I go first. But I do travel a lot, so I am curious. Now, there are some limitations and downsides to melatonin. I want to emphasize these. Melatonin doesn't address every cause of insomnia, right? So if you've got severe anxiety, chronic stress, depression, chronic pain, sleep apnea, or other medical conditions, melatonin probably won't help you very much. It might a little bit. But the problem isn't circadian timing. It's something else, right?

So people are just biologically tired, but they're cognitively able to disengage. That's what we call hyperarousal. The brain's in an elevated state of vigilance. So melatonin alone can't fix that. Now, the other part is timing matters enormously. If you take melatonin at the wrong time, you can actually shift the circadian rhythm in unhelpful ways. So if you're going to take it, timing is a big thing. You don't take it when you're going to sleep, but you take it before you go to sleep. So you want to speak to someone about that and figure the timing out.

And there are side effects. For most people, melatonin's relatively well tolerated. But some people report, you know, and I've had this, groginess, headaches, dizziness, or even vivid dreams. In fact, I just had a chat with my son because he told me he stopped melatonin because of nightmares. And, you know, I've only been doing it for a little while. And I haven't had nightmares since I was a kid. And now I'm having nightmares again. So it brings us to one of the more interesting questions about melatonin. So why do some people get it and some people don't? Like, why do some people have these nightmares? And I'll talk about it. And I'll talk about it. And I'll

tell you the truth, my son asked me this very question over lunch just like an hour and a half ago. And the answer is, when I dug into this, no one's really got a great idea. You know, it does tie into dream sleep and the idea of dreaming and maybe melatonin somehow is changing the way REM sleep works, but maybe it's doing something different as well. So there is some evidence that suggests that melatonin changes REM density or it alters the transitions. But why a nightmare? I can honestly tell you no one really knows. The amygdala is still activated while you're dreaming and maybe it's impacting the amygdala as well. And I was hoping for a great answer for this one, but there you be. Now that's about all I have to say about the

neuroscience of melatonin. But if you're going to take melatonin like I've tried, I would tell you to really look into it, possibly even talk to your doctor, because melatonin can help in certain situations, but it can't fix all sleep problems, and it's important to realize that. So hopefully you've found this interesting, a bit on the neuroscience of melatonin, but if you're going to go down this road, I'd really tell you, you want to take a look at sleep hygiene first. All right, put away your phones and your laptops, avoid caffeine in the evenings, avoid anything that causes a state of alertness after about five o'clock at night. And one of my favorite lines with sleep hygiene,

which I used in the past on the podcast, is if you love dessert, don't have it after dinner, have it after breakfast. Get all that sugar in early. Okay, that's the neuroscience and melatonin. Don't forget the website, that neuroscience guy.com. There's links to our Etsy store and Patreon. So those are ways that you can buy some merch to support the podcast.

And by that, I mean the graduate students in my lab. and Patreon, where I've told you many times, if you haven't figured it out yet, just Google it or use chat, GPT. I'll tell you what Patreon is. There's our Instagram threads and X at that Neuroside guy. Jen's posting some awesome content on Instagram. So keep up with that. And of course, we always want to know what you want to know about the neuroscience of daily life. You know, this one was driven what I wanted to know about the neuroscience of my daily life.

but please send us your questions. Jen's compiling a big list. We review them. We try to answer the ones that we can. And last but not least, the podcast. Thank you so much for listening. And thank you for this uncut, raw episode. My voice, as you can tell, is starting to go because it's 15 minutes straight.

So I will end with this. My name is Olaf Kugalson, and I'm that neuroscience guy. Thank you so much for listening to the podcast. And I'll see you soon for another. full episode.