What's up with your nightmares?

Dreams of flying? Nightmares of teeth falling out? Falling off a cliff? As a sleep scientist at the University of Montreal, Michelle Carr https://recherche.umontreal.ca/chercheur/is/in35846/ has pretty much heard it all. In Michelle’s new book Nightmare Obscura https://us.macmillan.com/books/9781250342720/nightmareobscura/, she explores the science of dreams, nightmares – and even something called dream engineering, where people influence their own dreams while they sleep. Today on Short Wave, co-host Regina G. Barber https://www.npr.org/people/1082526815/regina-g-barber dives into the science of our sleeping life with Michelle Carr. (encore) Interested in any upcoming science books? Email us your question at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:16Regina Barber?

  You're listening to Short Wave from NPR.

• 0:24Regina Barber?

  You come home from work. You're exhausted. You finally get into bed, and your head hits the pillow. And then the next thing you know, your car is barreling out of control on the highway. You're going around that turn.

• 0:40Regina Barber?

  But you're in the backseat. You can't reach the brakes.

• 0:46Regina Barber?

  At least, that's my reoccurring nightmare. But when I told that to Michelle Carr, she wasn't phased.

• 0:52Speaker 02

  That is a very common dream theme. I have it all the time as well. I think it's just related to our physical body being like not really receiving any sensation of the car pedal. So the dream is like going out of control.

• 1:06Regina Barber?

  As a sleep scientist at the University of Montreal, her job is basically watching people sleep. So when it comes to dreams and nightmares, she's pretty much heard it all.

• 1:16Speaker 02

  Teeth falling out, or flying, or falling, or finding new rooms in my house.

• 1:23Regina Barber?

  Michelle is the author of the new book called Nightmare Obscura. In it, she explores the science of dreams, nightmares, even something called dream engineering, where people are able to influence their own dreams while they sleep. But why we dream or get nightmares is still a bit mysterious for scientists.

• 1:43Speaker 02

  We know so much about how important sleep is for our health, but we're only just beginning to uncover whether dreaming and the way that we feel during sleep is significant in our health as well.

• 1:57Regina Barber?

  And since humans spend somewhere around one-third of our lives asleep, we had to know more. So today on the show, why your nightmares go bump in the night. We dive into the science of our sleeping life with Michelle Carr and make nightmares a little more known, a little less scary. I'm Regina Barber, and you're listening to Short Wave, the science podcast from NPR.

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• 3:27Regina Barber?

  Michelle, sleep happens in cycles. So can you just walk us through the four different stages of sleep?

• 3:34Speaker 02

  Sure, yeah. When we first start to fall asleep, there's this stage where we're still a little bit awake and we just start entering a stage where our brainwaves start to slow down. And that's pretty obviously called stage one sleep. It's just a really brief period of sleep onset, a transition. And already in stage one sleep, we can start to have really bizarre thoughts or images that appear in our mind. And stage two is when our brainwaves slow down a bit more. It's a much more stable sleep state and we're really disconnected from the sensory environment. And gradually, we move into a deeper state, stage three, or slow wave sleep, where there are really a lot of very slow waves throughout the brain.

• 4:19Speaker 02

  And this is the state with the least amount of dreams. Our dreams are really short and brief and maybe thoughtlike when we're in stage three sleep, or we don't remember anything at all. And then the fourth stage is REM sleep. It's called REM because our eyes are moving, rapid eye movements. And our body and our mind are actually quite active during REM. Our, our brain is even, it looks very similar to wakefulness. We have a lot of really high frequency activity in the brain. And REM sleep is the stage when we also have the most vivid and emotional and sensory dream experiences.

• 4:58Regina Barber?

  It seems like, at least for me and many people, like, there's an emotional component to sleep. And, and in your book Nightmare Obscura, you write about a study you love where participants watched embarrassing videos of themselves singing and then their brain showed signs of shame, but that changed after a night of sleep. What does that tell you about like the importance of sleep?

• 5:20Speaker 02

  Yeah, I think this is maybe something that a lot of people can relate to, that, you know, we all go through different stressful experiences during the day. And at night, just before sleep, you might be worrying about, you know, an argument you had or like really stressed about, you know, something that happened during the day. And then after a night of sleep, if you think about that same problem, it almost, it seems completely manageable. And this is one of the functions of sleep. It's helping us to essentially, in a way, let go of a lot of the distress that we accrue during, during the day, like all of the emotions that get activated during the day. We kind of are, are able to let go of them during a night of sleep.

• 6:03Speaker 02

  And even for memories that we have, we, we let go of the emotion that's attached to them. So it helps us to adapt and to be better able to manage anything that might come up the next day.

• 6:13Regina Barber?

  It kind of sounds like exposure therapy.

• 6:15Speaker 02

  Yeah, I think that there is a similarity there in that you're, but I think one of, one of the keys about sleep and what makes it different from maybe like being exposed to stressors in waking life is that there's actually a very physiological component that the brain and the body are in a specific state where During sleep, we're able to reactivate emotional memories, like the amygdala is active, but our physical body is actually subdued in certain ways. So we think that's really essential to being able to strengthen and to hold on to and to store important memories, but to let go of the kind of stress and arousal that's attached to them.

• 6:55Regina Barber?

  And then that makes me think of nightmares, which mostly seem to happen in that fourth REM sleep stage. When our amygdala, which deals with fear, is more active, in your book, you call nightmares almost like a self-attack. Like, there's this mental autoimmune reaction. Is that what's happening? Like, why do we have them?

• 7:14Speaker 02

  Yeah, I guess part of that analogy is that the source of nightmares is something that we have experienced. And so it's, we do see that nightmares are specifically very highly correlated with past experiences of trauma or with adversity. They occur a lot more during periods of stress. It's almost like the memory is too intense and the emotion is so strong that it kind of disrupts sleep anyways. It causes the body to become really aroused and you just are, your sleep is interrupted and you wake up in a state of distress.

• 7:48Regina Barber?

  Are there any benefits of nightmares? You know, like this mental autoimmune reaction that we have in our minds?

• 7:55Speaker 02

  I mean, I think there's a benefit to bad dreams in general and even to occasional nightmares. And I think if nightmares are occurring occasionally or if you're having bad dreams, I think these are all reflecting what is an adaptive process of sleep and of dreaming, which is you're trying to work through these stressful or negative experiences that you've had.

• 8:17Regina Barber?

  So where do scientists see nightmares in the brain? Is this a different, like, part of our brain than pleasant dreams? I'm just so interested. Like, where do they live?

• 8:28Speaker 02

  Yeah, there's actually not too many actual recordings of people having nightmares in the sleep lab. This is one of the kind of curious things about studying nightmares, or any sleep disorder, actually, that patients who have nightmares or other sleep disorders frequently at home, they very rarely have episodes in the lab.

• 8:49Regina Barber?

  Wow, why do they feel safe in the lab?

• 8:52Speaker 02

  I know, we think, I mean, that's one of the theories. But in general, you know, we have some evidence that...

• 9:00Speaker 02

  Experiencing emotion or memories and dreams, it seems like it's the areas of the brain that are active in waking life. But there is some work on kind of the brain basis of nightmares and nightmare disorder. And one thing that we have seen is that people who have nightmares potentially have a difference in how their brain regulates emotion. And specifically, we know that sleep is important for emotion regulation, and it specifically helps this connection between basically frontal or prefrontal areas of the brain, which are responsible for helping us to control

• 9:43Speaker 02

  and to regulate our emotion, and their connection with the amygdala, with our emotional arousal centers. So in people who have nightmares, what we see is that there's actually less activation in the frontal areas of their brain when they are experiencing emotional distress. So in principle, we think this means they're less able to regulate and to control and to manage their emotion, and that this is occurring both during REM sleep, when emotion regulation is really maintained, and then this spills over into wakefulness as well, making them, they'll have a harder time managing and dealing with stress in waking life because of this.

• 10:26Regina Barber?

  Oof. And speaking of stress when you're awake, you mentioned in your book that there's a point where nightmares can become harmful to overall health. So what are some methods researchers use to treat nightmares?

• 10:39Speaker 02

  The main methods to treat nightmares are, imagery rehearsal therapy is the most common therapy, and there's just a lot of other variations of that. And it's basically a technique.

• 10:54Speaker 02

  What's called re-scripting a nightmare's content. Because nightmares very often have very recurring themes. So if somebody has a nightmare of a tidal wave or a nightmare of being chased, they tend to have these themes that recur over time. And it's almost like this script that's learned in your mental imagery. And so imagery rehearsal therapy works with, first, just a little bit of exposure to the nightmare, like kind of being more comfortable with looking at your nightmares, talking about them, writing them down, and not being so aversive to them. And then changing the nightmare in some way. So you write a slightly new script

• 11:36Speaker 02

  or, you know, change something so it's not so scary or make yourself more powerful. And it's a dream, so you can do whatever you want, really. And then you, before sleep, you visualize this new, more pleasant or more satisfying dream. Visualize that for 10 to 20 minutes before sleep each night. And over time, this decreases nightmare frequency. It makes people feel less distressed by their nightmares and it improves symptoms overall.

• 12:05Regina Barber?

  And this is the sleep engineering you were talking about, right? Like trying to do things to affect your dreams.

• 12:12Regina Barber?

  I have had personal experiences where I feel like I can alter things within my dream. Is that, is that normal? Have you studied that as well?

• 12:21Speaker 02

  Yeah, that's definitely very common. And that moves a little bit into what's called lucid dreaming, which is where you become aware of the fact that you're dreaming while you're still asleep. So of course, if you're fully aware that you're in a dream, you can control yourself and your own actions, but you can even potentially change the dream environment.

• 12:40Regina Barber?

  The scenery, yeah.

• 12:41Speaker 02

  Yeah, exactly. You can change things around you. But one thing that I find really interesting is even when you're not fully lucid, like even if you... Even if you just start to have more agency in your dreams, that can be beneficial. So kind of like you said, maybe you don't realize it's a dream, but you you have this thought like, oh, maybe I don't need to be afraid of this thing that's chasing me. Or, oh, maybe I can just change the scene or like move into a different room or something. You start to have essentially just just more of this choice and awareness, more awareness in your dream, even if you're not fully lucid, and that can be helpful for people.

• 13:24Regina Barber?

  One of the final chapters of your book, you talk about like exciting new technologies and methods to to study dreams. Can you give us some of those highlights of these new technologies?

• 13:35Speaker 02

  Yeah, and I mean, there's already, of course, a lot of like apps and ways to just record your dreams and follow like maybe different visualizations you can practice before sleep to influence dreams. But in our lab, we're we're pretty interested in new wearable EEG technologies. So these are like wearable headbands that you can use during sleep. They're getting better at being able to detect sleep stages in real time. And this means that we would be able to not only measure someone's sleep at home, but potentially use these types of wearable headbands to actually potentially influence sleep as it's occurring, using different types of sensory stimulation.

• 14:20Regina Barber?

  Like to shake you out of a nightmare or to like soothe you?

• 14:24Speaker 02

  Mm hmm. Yeah, there is one, I think, app and wearable technology that that's designed to maybe detect when you're basically when you're showing signs of arousal during sleep, which they're using as kind of a proxy for maybe you're experiencing a nightmare. And when they detect this state of arousal, they might present a vibration stimulus, which awakens you a little bit and it interrupts the nightmare as it's occurring.

• 14:53Regina Barber?

  You've made me think about my dreams even more. So thank you, Michelle, for talking to us today.

• 14:57Speaker 02

  Yes, thank you for having me. It was a pleasure.

• 15:02Regina Barber?

  If you liked this episode, you might want to check out our episode on melatonin and avoiding jet lag. We'll link to them in our episode notes.

• 15:11Regina Barber?

  This episode was produced by Rachel Carlson and edited by our showrunner Rebecca Ramirez. Tyler Jones checked the facts, and Kwasi Lee was the audio engineer. I'm Regina Barber. Thank you for listening to Short Wave from NPR.

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