Instant Genius - How to Hack Your Sleep: The science of bizarre sleep phenomena

Episode Date: November 4, 2024

Research over the past few decades has proven that getting a good night’s sleep is essential for our health and wellbeing. But sometimes strange things can happen in our brains while we’re asleep. In this episode, we catch up with Dr Dan Denis, a sleep researcher and lecturer at the University of York’s department of psychology. He tells us what happens in our brains and bodies when we dream, why some of us are prone to sleepwalking and even sleep eating, and talks about the strange phenomenon of lucid dreaming. This episode is presented in partnership with Lumie. https://www.lumie.com/ Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Hello and welcome to Instant Genius and bite-sized masterclass in podcast form. Every Monday and Friday, you'll hear world-leading experts and scientists talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. Research over the past few decades has proven that getting a good night's sleep is essential for our health and well-being. But sometimes strange things can happen in our brains while we're asleep. In this episode, brought to you in partnership with Loomie, we catch up with Dr. Dan Dennis,

a sleep researcher and lecturer at the University of York's Department of Psychology. He tells us what happens in our brains and bodies when we dream, why some of us are prone to sleepwalking and even sleep eating, and talks about the strange phenomena of lucid dreaming. Welcome to the podcast. Thanks very much for joining us. Yeah, thanks for having me. So first off, can you introduce yourself to our listeners and tell us what you do? Yeah, my name is Dr. Dan Dennis. I'm a lecturer in psychology at the University of York. All of my research is really around the topic of sleep. I'm interested in everything to do with sleep.

So I do stuff on how sleep improves our memory. I do stuff on how we can improve people's sleep to improve their mental health. But I'm also interested in, I guess, what we can call the weird side of sleep or more formally anomalous sleep experiences. So things like lucid dreaming and sleep paralysis and that kind of thing. So that's the topic of today's discussion. So let's start with the obvious one, dreams. What's going on in our brains when we dream? Yeah, so obviously we as a species have been fascinated by dreams, I think, pretty much forever.

Since records began, people have sort of postulated on why do we dream and do our dreams mean anything? In terms of neuroscience and our understanding of what's happening in the brain when we dream, I think that's a fairly recent interest people have had. I think historically people have kind of viewed the studies of dreams as being a little bit eccentric or, you know, not like a serious matter to study in terms of kind of neuroscience. But that attitude really changed over the last few decades or so. And we're seeing more and more studies coming out that have looked at what's happening in the brain

during our dreams. So usually what we do when we want to study dreams in the lab is we'll have someone come in and they'll go to sleep while we record their brain activity. Then basically what we will do is what a certain thing is. points in the night will wake them up and simply ask them if anything was going through their mind prior to they were waking up. And then what we do is we then go back into the neural data and look to see whether there are any differences in brain activity in episodes where people did report having a dream to where people did not report having a dream. That's the basic method.

So what can we learn from taking measurements when someone's dreaming? So generally what we find is we have an increase in activity in a part of the brain that's turned the posterior hot zone. This is an area position kind of near the back of the brain and it's where several of our different brain lobes meet. So our occipital lobe, our parietal lobe, our temporal lobe, they will kind of interact and interlink in this posterior zone. It's called the hot zone because it's kind of being theorized to be sort of one of the neural correlates of consciousness. So when people are unconscious for various reasons like anesthesia, for example, we see a reduction activity or no activity in this hot zone compared to when people are awake and interacting. And what we find is

is when people report having a dream, we actually see a very similar pattern of activity. So when people are dreaming, there seems to be increased activity in this neural corollate of consciousness that's absent when people are not reporting a dream. So they are becoming essentially more conscious. So what are the theories on the purpose of dreams? I know that's a difficult question. Yeah, so there's been many different theories have been proposed over the years. I think they kind of they sort of fall on a spectrum where on the one hand, some theories assign a very, very important role of dreaming in terms of, in terms of their meaningfulness. So, for example, you know, psychoanalyst place a big emphasis on interpreting dreams to understand people's mental health and so on.

On the other end of the spectrum, you have theories that are essentially saying that dreaming is the result of kind of random firing, sort of just complete randomness happening in the brain, the brain's randomly firing activity during our sleep. And then that's being interpreted as being some kind of dream content. I think the research that has been able to find sort of reliable markers of dream activity like the posterior hot zone is kind of speaking to this idea that when we're dreaming,

we're getting activity in the brain that's kind of consistent with what's happening in the dream. So dreams where we report a lot of movement, we get a lot of activity in the motor cortex of our brain that's responsible for our movements when we're awake. When our dreams are particularly vivid, we're seeing more activity in the visual cortex. So that's related to vision.

similarly like speech and dreams, lots of talking, that activates language areas. So I think in my sort of interpretation of the literature, what we're seeing and what's happening in dreaming is it's kind of essentially a byproduct of parts of the brain that we know are involved in various waiting fluctuations, they come back online during sleep and we interpret that activity as our dream content. So some dreams can be fun, but some not so much. So I'm talking about nightmares. And they can become a real problem for some people.

So what do we know about why they're? they occur and what can we do to help people who really struggle with them? I think we've all experienced a bad dream at some point in our lives, all experience a nightmares, so a very emotionally charged dream. I think that's very normal, very common to have the odd nightmare. Where it starts to become a problem is when those nightmares starts become more frequent and more intrusive. When we're thinking about nightmares as a sort of clinical disorder,

something that might require treatment, what we'd usually be asking is how distressful are the nightmares, not just themselves, but how much distress are they causing in other aspects of your life? Are you ruminating about the nightmare a lot? Do you have a lot of intrusive thoughts about the nightmare? Is it interfering with other aspects of your life? So does it, a lot of people when they are experiencing a period of very severe nightmares, will actually not want to go to sleep right because they're worried about having a nightmare,

so they're going to start sleep depriving themselves. This kind of more extreme version of nightmares can have a lot of different causes. It can be triggered by stress. It can be triggered by anxiety. You know that nightmares are common parts of a lot of different mental health. health conditions, PTSD is in particular. If you experience a traumatic event, it can be quite common to replay that traumatic event again as a nightmare. So these are the areas, this is where it can become a problem. In terms of treating nightmares, there's a couple of different things that

have been proposed. Quite a commonly used therapy is something called image rehearsal therapy. This has been shown to be effective. And really the idea of this, it's taking aspects of things like cognitive behaviour therapy. So you'd go speak to a psychologist, a therapist or some kind, and you'd essentially discuss the content of your nightmare with the therapist, try to work out what might be triggering the nightmare, that kind of thing. And then what you do is you then come up with the therapist, you work to sort of making a successful resolution to the nightmare. So if you're being chased down by a bear and the bear eats you in the nightmare, maybe in your therapy session, you can't have a situation where you can

escape the bear. Maybe you can, I don't know, jump over like a river or something or some sort ravine that blocks the bear from getting to you or something. And the idea is that you've rehearsed this narrative over and over again whilst you're awake. And the goal of this therapy is that when you go to sleep and you have the nightmare again, because you've rehearsed this content so well about a good outcome of your nightmare, hopefully that's going to actually influence your dream content and you will end up successfully escaping the predator or having some positive outcome of whatever the nightmare might be. And this actually has some parallels of how people train to the lucid dream in terms of rehearsing content. And actually, there is being

proposed that you could actually perhaps train people to lucid dream and then in their nightmares. So a lucid dream is when you become aware that you're dreaming, right? The idea being that if you're a nightmare, you could recognize this as a nightmare, it's not real, and then you could either use that to wake up, or if you can convert it into a lucid dream, you can transform it into something much more positive. You can take complete control and agency over the content of the dream. So let's have a look at lucid dreaming then. It's a fascinating topic. I recently read a study from the Netherlands where they had lucid dreamers practice playing darts in their dreams. And they actually got better at playing in their waking life. Yeah, there's a really interesting studies. And there's a real, one of the areas that I think has really pushed this kind of increased interest, I think, in dream research and modern psychology and neuroscience is the potential for actually using lucid dreams in a positive way.

like, for example, learning to play darts. And really, elucid dream in its core is essentially just becoming aware that you're dreaming. So that's sort of the first stage. You know, usually when we're dreaming, we'd have no idea that it's a dream. So when you become aware that it's a dream, that's the first step of a lucid dream. And sort of taking it to the next level is once you're aware it's a dream, you could then actually start to control the content of the dream and control your actions, control your movements.

So you could perhaps in your dream, set up your darts board, stand there and start throwing darts to try to increase your aim. when people have looked at lucid dreaming in the lab, it's a very hard thing to study in the lab because we've got to be able to induce lucid dreams in people, which are our ways we can do that. But what we find is if we put people into a brain scanner so we can see what's happening in their brain,

similar to a regular dream, when someone does something in a lucid dream, that that tends to correlate quite accurately with brain activity and brain areas that relate to that same action whilst we're awake. So again, when you're throwing the dart, there's going to be activity in your motor cortex, probably your cerebellum. These are areas of the brain that are involved in motor coordination.

And so you're basically activating the same areas again. So what's likely is you're actually kind of training, essentially, your brain to do the actions that you're carrying out in your dream. So can anyone lucid dream, you know, can we learn how to do it? Yeah, so some people just seem to be spontaneously able to lucid dream and maybe are surprised when they learn that people can't do this and that's not normal. and that isn't, I don't think that is the norm. Most people don't lose a dream, at least spontaneously. But there are ways we can teach ourselves to lose a dream. There's a few different ways.

If you've ever seen Inception, you'll have seen the spinning top to test whether he's dreaming or not. That is very much a real thing people do and it works. So the idea is it's called a reality check. So the idea is that you have something like a spinning top or what's often quite common if people try to push their thumb through their hand. And the idea is that regular intervals you do this reality check. And it has to become a habit every hour or something, every half an hour, do a reality check. And the idea is that eventually these checks will start to come into your dreams.

You'll start to do the reality checks in your dreams because it's become such a habit. And in the dream, the idea is that the reality check will break down. Even the spinning top will keep going forever. You know, your thumb will go straight through your hand. And that's meant to give you the insights because this has become such a habit that becomes a trigger. you know, okay, this is a dream. This doesn't happen when I normally do these checks. And then from there, you can go on to hopefully control the content. So that's one way you can do it.

Another thing that can increase the likelihood you're going to have a lucid dream is to kind of arrange your sleep scheduling in a very inconvenient way. But basically what we know about the normal sleep cycle is that you have most of your rapid eye movement sleep. This is the stage of sleep that's most associated with vivid dreams and lucid dreams. that tends to happen at the end of the night, the second half of the night. So when you go to bed at a normal time, you typically will enter non-rapid eye movement sleep. It's going to be a long time before you get any sleep

that's going to give you a lucid dream. But if you wake up, set your alarm for 3am or something, and you wake up and get really, really agitated, you sort of get really, really alert, maybe run around your bedroom or something, and then you come back into bed in this sort of hyper aroused state, and you close your eyes and you try really, really hard to stay away. to remember what it feels like staying awake as you're falling asleep.

What's going to happen is you're almost certainly going to fall into rapid eye movement sleep, which is the stage of sleep that we know is associated with lucid dreams. And because you're in this state of trying to stay awake, trying to stay conscious, the idea is that when you fall into sleep, you'll retain that little bit of waking consciousness and be more likely to have a lucid dream. Coming off the back of that, how about something called false awakenings? The false awakenings can actually often come from a lucid dream,

or the other way they can be a capri lucid dream. They can be a start of a lucid dream. So what a false awakening is, is it's kind of what it sounds like. The idea is that you wake up or you think you've woken up, you go about your normal morning routine, everything feels totally normal. And then usually something really bizarre or terrible happens. So a common example is you get ready to go out to work or something.

You go down the stairs, go up the front door. You step out at the front door and then you immediately get hit by a bus or something like that. And then that prompts you to suddenly jolt awake because that whole thing was actually a dream. and then you actually wake up for real. What can happen is you actually get into these loops of false awakening, so the false awakening can actually happen once, twice, three times.

It can happen or a kind of repeating loop over and over again, and then eventually you wake up for real. So sometimes these happen kind of towards the end of a lucid dream. Something really jorts your wake. Because the lucid dream was so real, you made me feel like you were actually awake. But other times it can happen just sort of spontaneously. Ambition comes in all shapes and sizes.

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What's happening there? Yeah, so sleep paralysis is one of these really, really, really fascinating things and definitely feels into the sort of the weird stuff when it comes to studying sleep. So sleep paralysis is in some sense quite similar to a little. lucid dream in terms of the mechanism, but it's very different in the experience. So in a lucid dream, you are in a dream, but you have conscious awareness that you're dreaming around the dream. And lucid dreams are generally reported to be quite positive experiences. People like having lucid dreams. What happens in sleep paralysis is you, again, are in this sort of partial wake, partial sleep

state of consciousness, except your eyes are awake and you can see your surroundings. And you look around, but you can't move at all. You're completely. paralys to the bed. And this is obviously already quite a scary experience, just in his own matter. But what can often happen a lot of the time is you then have these very intense and very scary hallucinations that come along with it. So people report a sense of presence in the room with them, some kind of like evil entity that they can't quite see, but they have this really intense feeling that there's something that this then can manifest into some sort of real bedroom intruder. So people report seeing murderers, aliens, ghosts.

You know, all kinds of things. So of coming into their bedroom, absolutely terrifying them, and often trying to strangle the person while they're sleeping. So people often feel a sense of pressure on the chest. This can be interpreted as whatever creature they're hallucinating, kind of strangling them, suffocating them. So yeah, it's really, really horrible. How about sleepwalking then?

This is something I used to do when I was younger. I'd walk around and even talk to my parents and then go back to bed. So what's happening there? So sleep walking is, in this sense, the opposite of sleep paralysis. So the reason that we're paralyzed in sleep paralysis is because we're coming out of rapid eye movement sleep into the waking state. And one of the key aspects of rapid eye movement sleep normally is that we are paralyzed. And this is probably so we don't act house our dreams. You know, I mentioned before that if you're making motor actions like throwing

the dart in a dream, that's activating your motor cortex, which is responsible for our actions. When we're in REM sleep normally, those parts of the brains are basically being inhibited. So activity is being blocked from reaching our limbs. We actually act out our dreams. And so in sleep paralysis, we kind of become awake while in room's sleep and we're paralyzed. So sleepwalking, we obviously aren't paralyzed. We're able to get out of bed, move around, walk around. Sleepwalking happens in non-rapid eye movement sleep, so maybe deep sleep.

It's quite difficult to know what's happening in sleepwalking. One thing we kind of think is probably the case is that people that sleepwalk tend to have essentially just a more active motor system in general, maybe have a more hyperactive. motor cortex. And so when they're in deep sleep, this is kind of acting more more highly. It's typically silenced in non-rapid eye movement sleep, but it becomes more active. So that kind of initiates those sorts of movements. It was thought for quite a long time that people are kind of essentially unconscious whilst they're sleepwalking. But there have been more recent studies that have tried to assess the mental content of people when they initially wake up. So if start

sleepwalking, usually what happens is a sleepwalking event happens with something we call a confusional arousal. They're asleep, but it looks like they're away. They might be rummaging around the bed, like looking for something that they might have dropped or lost or something like that. This is usually what starts a sleepwalking episode. And during those periods, just when people first start to move, people often do report having some kind of mental content, like a dream. It's usually something a bit distressing has happened, like they've lost something or they think something's fallen out of bed when it hasn't. But then from that, people then will go and have more complex behaviours like walking around the house.

talking to people, sometimes people report eating. Whether they're asleep, you know, if they empty their fridge out and then they don't know where all their food's gone the next day, the people can perform quite an elaborate set of activities whilst they're sleepwalking. Yeah, I used to have a housemate that used to sleep eat. You'd clean the fridge out at night without realizing it, and then the next day would be like, well, who ate all the cheese? It's a funnier one, isn't it?

Usually when people, if people know that they're doing this, that they're eating in their sleep, people will go to quite some lengths to stop them from doing it. So they might put a lock on their fridge or, you know, seal up the cupboards at night so that they can't eat. Because obviously, in extreme cases, this can really contribute to health problems, right? If people are eating a lot more food than they should be, you know, people have a whole meal, is they eating a whole block of cheese every night. It's not, in the long run, can not be good for you. So let's talk about sleep talking.

When I was younger, I remember hearing about a guy named Dion McGregor, who used to speak in full sentences. in his sleep and his roommate ended up recording him. It's really crazy stuff. Yeah, that's a really interesting case is he seemed to be such a vivid, a vivid sleep talker, should we say. I actually think that those recordings got made into some kind of like psychedelic music album, I think, or something, which is kind of fun. But yeah, sleep talking, it's pretty common, not at the level that he had. A lot of people will, you know, kind of throw out the odd word, like the odd mumble, that kind of stuff. maybe more elaborative sleep talking, where people sound like they're having conversations

with imaginary characters. It's a bit less common. You kind of would think that in general that might map onto dream content, and it does sometimes, like people kind of, they're having a conversation in their dream and then it maps on quite nicely to the dream.

But other times it doesn't map on that well. Like, it just can be something a bit more, feeling like a bit more random or without a sort of obvious cause. Again, it could be, in some cases, the result of some kind of, essentially, random sort of activation in the brain that happens during wake, we have these things called Ictyl automatisms, which are kind of just random localisations movements that are

caused by just spontaneous firing of neurons in the brain, surges and activity. So it could be due to that. But it does map into dream content sometimes. It's quite common that it maps into nightmares, so when the dreams are particularly emotionally laden, sleep talk, might be a bit more, a bit more common. How about another strange one then? It's got a very strange name, exploding head syndrome. Yeah, exploding head syndrome. Probably has the most evocative title of everything we're talking about. People's heads don't explode. Let's make that clear straight away. So exploding head syndrome is something that can happen in the transition from going awake to falling asleep. And basically what happens is that as a person's falling asleep, they perceive a really loud

noise like inside their head. Sounds like an explosion or a gunshot, something very loud, very short, very scary again. Obviously, we need to make sure this isn't something that's really happened. It's not just a door that slammed. This is the hallucination again when it's exploding head syndrome. And it's likely just essentially a byproduct of what's happening in our brains whilst we're falling asleep. So as we go from weight to sleep, we get a kind of progressive shutdown of our various century cortices. So our areas are our brain controlling vision, controlling sound. These areas start to kind of shut off, essentially, it's a falling asleep. It's like, that a loud bang could just be a sort of a reflection of this disjointed nature of our brain

systems as we're falling asleep. So it's again a spontaneous firing in the auditory cortex. That could cause the banging sound be perceived as a bang. People were speculated that it could be something to do with something happening inside the ear itself as we're falling asleep. It's really something's happening during the transitional state between waking and sleeping. So we've talked about a lot of different phenomena there. And if anyone listening is experiencing any of these things, you know, nightmares, sleep paralysis, exploding head syndrome. At what point should they seek professional help? You know, all of these things you've been talking about, in general, they're not something to be worried about. You're having an episode of sleep paralysis

can't actually harm you, physically speaking. Really, the test is a degree to which these experiences might be interfering with the rest of your life. If you don't want to go to bed because you're worried about sleep paralysis happening, that can have more serious consequences, right? You know, sleep at probation is very bad, after many reasons. So I think in those more extreme cases, it would be appropriate to seek out help.

What we've actually found in some of our research with things like sleep paralysis and exploding head syndrome, these are quite unusual things. Often doctors don't really know what people are talking about. You know, it's not something to come across very often. We have found that generally just kind of knowing that these things are intrinsically, not dangerous and they're actually pretty common. I think as a third of the population will have

at least one episode of sleep paralysis in their life. That can actually in itself bring reassurance. You're not going mad. You're not being attacked by aliens in the night. It is something that we understand and it's something that is not inherently, inherently dangerous. Thank you very much for listening to this episode of Instant Genius brought to you from the team behind BBC Science Focus. That was Dr. Dan Benis. If you liked what you just heard, then please do consider as subscribing to Instant Genius on your preferred podcast platform. The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines

or download us on your app store of choice. You can also find us online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision. with analog warmth. Alongside French acoustic specialist focal,

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