Revisited: The surprising science of dreams and nightmares

0:00This is The Guardian.

0:09Hi, Ian here. The Science Weekly team is on a break, but we'll be back with some new episodes for you next week. For now, we're going back to a few of our favourites from the year so far. If you've ever woken up from a strange dream and wondered what on earth your subconscious was thinking, this might be the episode for you. I spoke with dream scientist Dr Michelle Carr about the fascinating science of dreams and nightmares. I hope you enjoy it.

0:41Dr Michelle Carr has an unusual job. She spends her time watching people sleep. So as a dream scientist, you know, I work in a sleep lab and we invite subjects into the lab, usually in the evening. Before they can get cozy, Michelle's subjects are hooked up to electrodes on their scalp and face. Then it's lights out. The subject will go into a bedroom, which we've tried to make kind of homey with a nice night table and a nice bed. And they'll sleep and we are watching their brain activity and their eye movement activity. And we have a video of them sleeping in bed. But brain activity and eye movement only get the scientists so far.

1:28To really get an insight into the mysteries of dreams, Michelle and her colleagues have to do something a little unkind. Periodically throughout the night, we just wake them up. We use a two-way intercom to kind of call their name. And after they wake up, we ask them about their dream. And then they can go back to sleep. And we just repeat this process multiple times across the night to collect as much dream content as we can. The dream content Michelle has collected over her two decades as a dream scientist has informed her new book, Into the Dream Lab, the new science of dreams and nightmares.

2:03From studying dreams, we can see that the scaffolding of dreams is really our experience from waking life. And there are certain features that really often reappear in dreams and really they're like a simulation of our reality. So today why do we dream? What happens when dreams go wrong? And how can we take control of our sleeping life? From The Guardian I'm Ian Sample and this is Science Weekly.

2:41Michelle is an assistant professor of psychiatry and addictology at the University of Montreal and directs the dream engineering lab there. As you can imagine with all those late nights in the lab, her dream life is patchy. Yeah, it's kind of a problem of being a dream researcher is that we are sleep deprived and a little dream deprived during experiments. Occupational hazard. Yeah. I wondered if you could take me through a kind of what a typical night of sleep looks like in terms of its relevance to dreaming. And I'm thinking about, you know, whether our dreams kind of change across the night.

3:18I mean, we hear a lot about REM sleep, but is that the only time when we dream? So across the night, we go through four different stages of sleep. So starting early in the night, right as you enter sleep, you go into a really light sleep called stage one sleep. And then you descend into gradually slower, deeper stages of sleep, stage two and stage three. And historically, these stages have been less studied related to dreaming. And people have focused on REM sleep, which is the stage that occurs really at the end of the night and especially in the morning. But we actually dream in every stage of sleep.

3:53So if you wake people up all across the night, the majority of the time they will remember some type of conscious experience that they were having during sleep. It's just that the type of experience changes. So during a deeper stage of sleep, people might have not a very vivid experience. Maybe they even feel like they're just thinking. And then at the end of the night is when we have REM sleep. And that's the state where the brain is really the most active. From the brain activity, it almost looks like wakefulness. Sensory cortices are active, emotional regions of the brain are active, and people really experience the most vivid and immersive dreams during this date.

4:30And what about the purpose of dreams, Michelle? Does science really give us any clues as to why we're dreaming in the first place? There's a lot of different avenues of research looking at potential functions of dreaming. One of the main ones is looking at how dreams are related to memory processing, because this is a major function of sleep is essentially reactivating memories and strengthening or consolidating those memories that are important. So as an example, if you have someone do a certain learning task before they go to sleep at night, then during the night, if we collect their dream content, we might see aspects of that learning task showing up in their dreams.

5:11And the people who dream more about that learning task are actually going to have a better performance in the morning. So the dream content is reflecting processes of memory consolidation that are occurring across the night. And are we also using dreams to play out hypothetical scenarios or perhaps even play out scenarios that we've been in that we haven't maybe handled very well? Is there some element there where we're almost running simulations in a way in our brain? Yeah, you know, it's not just consolidating memories that we've experienced. It's also trying to learn from them. There's this view of dreams as a simulation or a rehearsal space where we re-encounter things that we face during the day, but there may be slightly different scenarios.

5:59There's slightly more bizarre scenarios. There's kind of evolutionary models that frame dreaming as perhaps a space where we can rehearse how we respond to threats, how we would respond if something is chasing us or somebody is threatening us, and it enables us to be better prepared for similar situations in the future. One of the things that often comes up when people are discussing dreams, and often the reason people are keen to discuss dreams, is that they're just so strange. And what is it that explains that sort of sense that they're so odd that perhaps disparate things will be connected?

6:36Right, yeah, the bizarreness of dreams. In part, it's because, especially in REM sleep, there's this really what dream scientists call a hyper associativity that's occurring, that there's a lot of activation occurring across cortical regions of the brain. And we think that this is enabling us to make associations that are really broad and really wide throughout memories in the brain. So we maybe are making associations between something that happened yesterday with a memory from a year ago and a childhood memory. And this is useful kind of in creative thinking, but also more broadly, it just helps us to integrate each experience into this really broad autobiography that we have of our entire life, you know, drawing connections through so many things that we've experienced in the past.

7:32When I spoke to people ahead of doing this interview, because of course I had to, A number of very common dreams came up when people wanted to share them with me. For example, there's these stress ones we think of, like the surprise exam we didn't realize we had, or flying, probably a positive one, trying to get somewhere and feeling like you're wading through treacle. I wonder, are there common themes? And do you get any insights as to things that are driving common themes when they exist? Yeah, definitely there are common themes. We call them typical dream themes, and they've been studied quite a bit across cultures and across different age groups, and over 40 of them have been discovered.

8:16The ones you mentioned are very common, dreams of flying, dreams of being chased, dreams where you're trying again and again and again to accomplish a task, but you can't quite do it, out-of-control cars or teeth falling out. So there's a lot of different potential reasons for some of these themes. And I don't think there's just one answer for why we have these dreams. I think some of them are actually related to the physical sensations of sleep. So I mentioned the dream of teeth falling out. And there was one study that showed that that's actually related to having dental distress. So maybe people who are clenching their jaw or grinding their teeth at night.

8:54And it's just the mind making sense of the sensation. Sometimes people in their dreams, they have this sensation that their body is slowed down, like they can't move or control their body very well. And we think that that might also be related to the fact that during REM sleep, our body is actually physically paralyzed. And this serves a purpose, you know, it keeps us from acting out our dreams. But the sensation of paralysis seems to sometimes become incorporated into the dream so that you feel that your dream body is unable to move and is really slowed down. But other ones are obviously more psychological, like the dream of missing an exam.

9:34It's fascinating that people report this for years, for decades even, after they're outside of school or college or whatever. And it seems like sometimes just the stress of having to perform is triggering this dream of failing an exam or being unprepared for an exam. I feel like over time, what I consider and presume to be anxiety dreams have actually changed over the years in that, you know, they used to involve things like unexpected school exams I hadn't prepared for. And now they seem to be about going back to university as this sort of aged students to study subjects I know nothing about.

10:11And we had a listener, Anissa, got in touch about this too. Hello Science Weekly, I'm Anissa, tuning in from Tokyo, Japan. And my question is, from childhood to old age, our dreams evolve. What does science know about how and why are dreaming changes over a lifetime? So has there been much research on how our dreams or whether our dreams evolve as we age, as we get older? Yeah, there's been some research on dreams across the lifespan. So far, it's primarily looked at like really general traits of dreaming. We know that actually dream recall, dream frequency, dream vividness, it becomes less and less over the course of older age.

10:59One thing we know is that the number of dream patterns or dream themes that people have also decreases over time. So it's almost like their dreaming life becomes less diverse over time. But there's still, I think, a lot more to uncover about aging and dreaming and even how dream themes change across a lifespan. Another question a few of our listeners wanted to ask was, why do some of us remember our dreams and others seemingly don't? And is there any way to sort of increase our ability to remember them? Yeah, this is a very common question that I get. Definitely there are differences in how frequently people recall dreams.

11:40Some of the reasons for this may be actually kind of biological. When we wake up in the morning, we're actually changing states of consciousness, right? It's quite a difference in brain activity between being deeply asleep and waking up. And it's a difficult process for the brain and for the mind to recall a memory across this change in physiological state. And what we can see is that some people, as they're waking up, they actually have more brain connectivity. And we think that this is maybe helping them to kind of carry the memory of a dream into the state of wakefulness. But we still think that pretty much everyone is dreaming.

12:21It's just this process of recall that can be difficult to access. But there are some kind of tips and techniques that you can use to increase dream recall. So we might ask people, when you wake up in the morning, stay still, stay in bed, keep your eyes closed, rather than waking up with an alarm and getting out of bed, that's going to really interrupt your ability to recall dreams. and also just when you get in bed at night you can kind of set the intention to remember your dreams maybe keeping a dream diary recording whatever you can every day this is going to over time increase the kind of the access and the amount of dreams that someone can recall the big question obviously that comes up all the time is how much if anything we should read into our dreams you know there are these old cliches like dreaming that your teeth are falling out means that you have money worries or something like that.

13:13But, you know, putting those aside, can dreams offer sort of insights that might be useful to us in our waking lives? And this was something our listener Karina wondered about. Yeah, dreams, I think, definitely can offer insight. I've worked on a couple studies where we've shown that participating in dream discussion groups where you follow, you know, certain techniques of talking about the dream and then talking about how it's related to your waking life. It can lead to insight into your personal life, insight into maybe some emotional things you're dealing with. And they can also lead to increased empathy, increased connection between people.

13:54So there are definitely benefits that can be had from either just recording dreams on your own or reflecting on them with other people. I think it really veers away from the kind of stereotypical dream interpretation we think of. like you were describing, like the dream dictionaries. It's not like that at all. It's more just discussing dream content and reflecting on how that's maybe linked to other things that you're experiencing in your life at the moment.

14:26Michelle, we've talked about how dreams can be both good and bad, but in the book, you make a distinction between a bad dream and a nightmare, that nightmares are more sensorially intense. They're more likely to wake us. And of course, they're particularly scary. And we had a couple of listeners get in touch about nightmares. Here's Sean. Hi, Science Weekly. After a period of quite intense stress in my early 20s, I started to have nightmares every night. It's been about 10 years now, and they continue to happen pretty much every night, even though they're a lot better than they were. So my question to you is what is the science behind prolonged periods over years of nightmares as opposed to nightmares that just happen randomly?

15:16So what do we know about why some people experience more nightmares than others? They're related to experiences of stress and adversity and trauma in waking life. So people who have experienced more even early childhood adversity or more are undergoing a period of high stress or transition in their life, these experiences are going to trigger nightmares. You know, it also depends on the person. I mean, some people are more likely to develop nightmares in response to stress. And it seems to be especially people who are more maybe emotionally sensitive or even what we call they have high sensory sensitivity.

15:56So they're likely to have very vivid imagination. So it's almost like they have really intense and vivid dreams. And when these dreams become negative, they become nightmares. They become really intense and disruptive. Should we be thinking of nightmares as being sort of purely maladaptive, just, you know, essentially bad things? Or do they seem to actually have some value, perhaps if they're not horrendously intense and crippling? Well, we do think that bad dreams in general are still healthy and functional and maybe adaptive in some way, that they're helping us to process stressful experiences from life.

16:36and even occasional nightmares are not necessarily a cause for alarm but it's really when they become too frequent and they develop into what's called nightmare disorder where you're having nightmares maybe on a weekly basis and it's really interrupting your sleep and it's causing a lot of waking distress that it you know develops into this pathology which really deserves treatment because otherwise it can just lead to increasing mental health symptoms. Is there anything that nightmare sufferers can do for themselves if they want to try and reduce their impact or their frequency? Yeah, the main treatment for nightmares is called imagery rehearsal therapy.

17:20And the basic techniques, I think, can be followed by most people even at home, rather than avoiding them or suppressing them, which is a pretty typical response to nightmares, writing them down and then the main technique is called re-scripting and this is where you actually rewrite the nightmare into a different version maybe a more positive dream so you change something about the nightmare and this is also based on the fact that nightmares are often very recurring and repetitive so during re-scripting you try to just change the content of the nightmare in some way to make it feel more positive or more satisfying.

17:57And then you rehearse this new form of the dream. Maybe right in bed before you go to sleep at night, you imagine this more positive version of the dream. And doing this over time reduces nightmare frequency and leads to generally less negative dreams over time.

18:16Coming up, how can we take control of our dreaming life?

18:34So, Michelle, what you're talking about there is this technique of dream engineering and you run this dream engineering lab. it actually sounds in a positive sense like it actually sounds great fun and it makes me wonder if we can control our sort of normal dreams in a positive way to I don't know explore new worlds or new situations yeah definitely dream engineering is it really can be this broad range of techniques that we use to try to influence the content of our dreams and one of the main focuses is treating nightmares and overcoming nightmares but we can also explore using different methods to try to have more creative dreams.

19:13One study in my colleague's lab, they looked at inducing flying dreams. I mean, flying is one of the most positive and kind of euphoric dream experiences. And that's an enjoyable dream experience that can make you feel good when you wake up in the morning. Musicians talk about practicing their instrument in the dream, or athletes can practice their sport in a dream. So there's all sorts of different ways that you can start to use your dreaming life, either for fun or for inspiration. And just finally, Michelle, I'm sure some of our listeners will want to do some experimentation with this. What are your top tips for trying to take control of dreams and even to be able to lucid dream where we work out that we're dreaming and take charge of what's happening?

20:02Well, there's a few different techniques. One of them, quite simply, is when you go to bed at night, if there's a particular theme that you want to dream about, you can spend 10 or 15 minutes while you're lying in bed, really visualizing the type of dream experience that you want to have. This is called dream incubation. But for lucid dreaming as well, there are other techniques. One of them is throughout the day, you can do something called reality checks, which is where maybe 10 times across the day, you remind yourself to check whether you're dreaming or not and just take a moment and look around at what you're experiencing and ask yourself if what you're experiencing is like a dream.

20:43It's kind of training your mind to pay attention. And if you do that while you're asleep, then of course you will realize that you are in fact in a dream. We know that for lucid dreamers, over time they'll be able to become lucid more easily and they also develop skills within the dream. So someone is gradually better able to control themselves and better able to control their dream environment and actually initiate dreams about the things that they want to experience. Yeah, well, it's absolutely fascinating. Michelle, thanks so much for coming on. Yes, thank you for having me. Thanks again to Dr.

21:21Michelle Carr. To support The Guardian, you can order her book, Into the Dream Lab, The New Science of Dreams and Nightmares, from The Guardian Bookshop. Just head to guardianbookshop.com. And thanks to all the listeners who got in touch with their questions about sleep and dreams. If you enjoyed the episodes, do give us a review wherever you listened, as it helps others to find the podcast. And that's all from us. Today's sound design was by Ross Burns, and the executive producer was Ellie Bury.

22:05Thank you.