Kim Mills: It’s the end of the school year and exams are approaching when you suddenly realize—you forgot to drop that advanced calculus class. You haven’t been to a lecture or turned in an assignment all year and now the final exam is tomorrow and your final grade is going to be a zero. The terror is real, but then you wake up and realize it was just a dream.
Or maybe your recurring dream is that you can fly, or that you’ve lost your teeth, or that you’ve found a secret room in your house that somehow you had missed for years. If you are like me, you probably wonder where do these dreams come from and what, if anything, might they be trying to tell you. Psychologists have also long wondered about the origin and purpose of dreams. Today we’re going to talk about some of their fascinating research and what we know—and don’t know—about why we dream.
So, why do we dream and do dreams serve a purpose? What’s the relationship between our dreams and what happens in our waking lives? Why are some dreams so common, such as being unprepared for a class or showing up naked in public? Why do some people have particularly vivid and memorable dreams and other people say they never remember dreams at all? Is it possible to influence the content of our dreams or our dreams totally out of our conscious control?
Welcome to Speaking of Psychology, the flagship podcast of the American Psychological Association that examines the links between psychological science and everyday life. I’m Kim Mills.
My guest today is Dr. Mark Blagrove, a professor of psychology at Swansea University in Wales. He studies sleep and dreaming and his research interests includes sleep and memory consolidation, the relationship between what happens in our waking life and our dream content, and how sharing our dreams with others can build empathy and help our relationships. He is the author, with Swansea University art professor Julia Lockheart, of the book, the Science and Art of Dreaming, published in August. Dr. Blagrove is a fellow of the British Psychological Society and a consulting editor to the APA journal Dreaming.
Dr. Blagrove, thank you for joining me today.
Mark Blagrove, PhD: Thank you for having me on the program, Kim.
Mills: So let’s start with the big question. Why do we dream? I know there’s not one simple answer to this question, but what are some of the main reasons that scientists have proposed that people dream?
Blagrove: Yes, there are indeed many theories for why we dream that have been put forward. One of the oldest ones is that it’s to do with our memories being interconnected while we sleep, and that we’re connecting our recent experiences with past experiences in order to consolidate or make permanent and make interconnected the memories. That’s one very current theory, which is also quite longstanding.
There’s a threat simulation theory that holds that we practice overcoming threats in our dreams. So for example—like, Kim, you’ve just said the threat of being unprepared for an exam, maybe we actually dream of these awful circumstances in order to practice overcoming them in a safe environment. That’s another one.
There’s emotion processing theories as well. There’s a fear reduction theory which holds that we dream of our fears, but we dream of them in such a way that the fears then become diminished. And needless to say, there is also the epiphenomenal view which many scientists would hold, and many members of the public would hold, which is that we dream for no purpose at all. It’s just the running over of our daydreaming into our sleep. Evolution hasn’t got rid of it because it’s not really that detrimental to us, and we just have these passing images as we sleep and they’ll disappear unless we wake up and remember them.
Mills: In my introduction, I describe the common dream being unprepared for an exam. Many people have this dream even years after they’ve graduated from school, and there are other common themes such as flying or being chased or losing your teeth. Do dream researchers have any theories about why these themes appear in so many people’s dreams?
Blagrove: Yes, there have been studies on typical themes in dreams that’s quite correct. There’s a problem with studying it, which is that, so for example, the dreams of teeth falling out. Often the studies are done on these and they find out, have you ever had such a dream? And so some of these dreams may actually occur only a few times in someone’s lifetime, but they’re really quite memorable.
But there are really deep common themes going through dreams. I mean, the one of finding a new room in your house is really quite striking when it happens. And a lot of people will have that a few times in their lifetime as well. And so we do have these themes, especially of threats—and lucidity as well, where you realize that you’re dreaming while you’re dreaming. But overall, although we remember these, they’re possibly not as common as they appear, and that are more ordinary dreams, depict our waking life and depict the circumstances and the concerns and concepts we have in our waking life, as well as bringing in these well-known themes as well.
Mills: Is there some therapeutic meaning to any of this? For example—I mean, I’ve had that dream about finding secret rooms in my house and I’m wondering, is that symbolic of something that might be happening in my waking life? And maybe I’m asking you to be a dream analyzer at this point, but I’m just wondering what you find out from the research that you do.
Blagrove: There is certainly the belief among many therapists that if you dream of a new room or an extra room or a so-far-undiscovered room in your house, then that does tie in possibly with the person discovering new things about themselves or wishing to discover things about themselves or something about their past, for example, something like that. The main thing though for these themes is that, as indeed Freud said, that what we need to do is to rather than decode things as if this is what this must always mean, is to ask the person for their associations to it. And what would a new house, what would a new room in your house mean to you? Why from your waking life are you choosing that particular image to put into the dream?
Mills: So essentially we interpret our own dreams. I mean, we kind of know what the associations are rather than having some universal—like these little dream books that you can buy in the drugstore that tell you that if you dream this, it means that.
Blagrove: Yes, that’s certainly not given any scientific credence to go buy those books. Sometimes I guess some of the comments in them might give you an inkling of what something could possibly mean. But on the whole, the view is that we ought to search for the memory sources of what’s forming our dreams. Freud called this free association. You think about particular components of the dream and you work out what they’re close to in your waking life or recent waking life experiences. The interesting thing though is that although it’s the person doing that, saying the associations, it’s often very, very difficult for the person to do that on their own. It’s actually quite useful to have somebody else ask, well, what does that mean or what does that remind you of in your recent waking life? Because often we have these enormous blind spots on things and even the experts, even the therapists, myself, others, we’ll often completely miss what an association is to a piece, to a part of our dreams, unless somebody who knows us quite well points something out.
Mills: Why do some people seem to have very vivid dreams and others don’t have them, or they don’t remember them when they wake up?
Blagrove: Yes, there has been—on the fact that there is a wide difference in between people. There’s a wide individual difference in what’s called dream recall. Frequency surveys seem to find that about a third of people have at least one dream per week, about another third have at least one dream per month, and another third have fewer than one dream per month. So they’re less often. And over the last 15 years or so, there’s been a lot of work in neuroscience on what distinguishes the high from the low dream recall frequency people. And one of the things that seems to happen is that there’s areas, an area at the front of the brain and an area at the back of the brain which are more active in frequent dream recallers. And these areas are also active during waking life. But the important thing seems to be that they’re active during sleep and the dream recallers have more activity in these two areas.
And what has also been found is that if the area at the back of the brain, there’s two lobes, one called the temporal lobe, one called the parietal lobe, and there’s a little meeting place between them. At that junction, if there is damage to that junction, then the person stops reporting dreams at all. And there’s a very famous book in 1997 by Mark Solms called The Neuropsychology of Dreams, in which he looked back at a hundred years of case studies of brain damage and found out for people having damage in this particular area and another area at the front of the brain, if they were damaged, then dream recall would stop. And so he put forward the idea that maybe there’s an area at the front of the brain that generates the content of the dream and it passes that information to the back of the brain where the imagery occurs. So it seems to be that there’s more activity in those areas in frequent dream recallers and possibly in the really vivid dream recallers as well.
Mills: That’s interesting. Is that in any way connected with the way our brains process vision? Because dreams are visual for the most part. So are our eyes actually functioning during our dreams?
Blagrove: For many people who are sighted, yes, our dreams are visual, but the area at the back of the brain is not quite the occipital cortex, which is at the very back, which is the main visual area. It’s more to do with an area to do with visual imagery, which is just in the front of that. And in fact, there are some people who have a condition which they don’t have visual imagery. And so for example, for people who you could ask how many windows are there at the front of your house, some people will just be able to see the front of their house and count the number of window panes. There are some people who just can’t do that. And it does appear that the people who have a complete lack of visual imagery also have a lack of dreaming as well. So it seems to be that the connection is with the imagery areas of the brain rather than the visual areas, which are more where the visual input comes in.
Mills: Now I tend to have wildly vivid dreams that often involve well-known people. For instance, last year I dreamed I was in the Brazilian jungle hunting for vampires with Jamie Lee Curtis, and I dreamed I was playing tennis with Rudy Giuliani who was using a broken ping pong paddle. Now my friends seem to enjoy it when I post some of these crazy dreams on social media. And I’m wondering, do people derive some kind of psychological benefit from recounting their dreams to friends and family?
Blagrove: Now that’s a very good question. There has been over the last 20 years or so, some papers on this in which, first of all, the frequency of telling dreams to friends and family has been assessed and that’s been assessed for the simple reason, or one of the reasons for assessing that, is that many people say that it’s very rare for that to happen, but it really isn’t that rare for it to happen. It’s about a third of people to about a half of people do recount their dreams once a month to somebody else. So dream sharing is really quite common.
And there’ve been several papers written on the benefits of that to people and to their friendships and relationships of sharing the dreams to other people and the greater closeness that results as a result of that. There’s even then been work done on the motivations for sharing dreams and the fact that they can be shared for entertainment or out of a wish to find out more about dream, or because the other person is in the dream and so they want to share it for that reason.
But whereas all that work had been done for many years, we at Swansea, in my work with Julia Lockheart, the artist I work with, we had conducted dream groups with dream sharing because we’re interested in the memory sources of dreams. That was one of the reasons. And we noticed that we had a greater consideration and understanding of the life circumstances of the people sharing the dreams with us as a result of public dream sharings. And we therefore set up experiments in which pairs of people were recruited, one person would tell a dream to the other one that they had. This was after recruitment when they had their next dream, they were told call each other up, meet, discuss the dream. They were given a protocol for the discussion of the dream. And prior to the discussions, they filled out a state empathy questionnaire that assessed how much empathy each person had towards the other person of the pair.
And what we found was, and what we found was that after one to four dream sharings, there was a significant increase of empathy from the person who was listening to and discussing the dream towards the dream sharer. And we published a replication of that in the APA’s journal Dreaming. We originally published it in Frontiers in Psychology, and it’s a very interesting finding. We didn’t find a change in empathy between the person who’s had the dream and is telling their dream to the other person, their empathy to the other person. Because as you might expect, because they’re concentrating on their own dream and their own life, they’re not really finding out more about the other person. So they don’t have a change in empathy towards the other person. But we’ve certainly now shown that there’s an increase in empathy, with empathy being rigorously assessed, as a result of dream sharing. And what we’ve also suggested is that if people take it in turns to do that dream sharing, they may very well have increased empathy with each other and that it may indeed counteract decreases in empathy that we seem to be seeing across Western society at the moment.
Mills: Let me ask you, some of our listeners may have heard of sleep cycles and the difference between rapid eye movement or REM sleep and non-REM sleep. How do REM and non-REM stages relate to dreams and why do we dream only during certain portions of the sleep cycle?
Blagrove: Yes. In 1953, there was the very famous experiment which actually by chance found that there was periodic periods of rapid eye movement during the night. And over the years it was found out that every 90 minutes a period of rapid eye movement starts and the periods of rapid eye movement, they’re about five minutes near the start of the night and they get as long as half an hour near the end of the night, and you may have five of these periods during the night. What was also found in 1953 was that if somebody was woken up from such a period, they were more likely to report a dream than if they were woken up from non-rapid eye movement sleep. Now since then, we’ve realized that there may have been a bias at the time to thinking that dreams occur in rapid eye movement sleep and that therefore people were dismissing the dreams that occurred in non-REM sleep. Maybe they were very short, maybe they weren’t very visual, but we now realize that dreams do occur in non-rapid eye movement sleep as well. And in the sleep lab, about 80% of awakenings from REM sleep result in a dream and 50% of awakenings from non-REM sleep result in a dream being reported. The non-REM dreams are usually shorter if you measure it by number of words.
And as the night progresses, you are more likely to have a dream. So as you get more into the sleep across the night, there’s a greater chance of the dreams occurring. And there is this difference though, between the sleep stages in the dreams being reported, but we do seem to be able to report a dream from most parts of the night. We can never quite tell whether somebody is going to report a dream or not though. And an interesting recent finding was that, there was an interesting recent finding which assessed people’s EEG across the night, woke people up repeatedly during the night, and it was able to be predicted eventually by an algorithm that was developed whether the person would wake up with a dream or not with a dream.
And this was the finding that there’s an area, again, like I said earlier on, near the back of the brain, which if that is very active, then the person is more likely to report a dream. So we do seem to report dreams throughout the night, but it seems to turn off and on and it’s more likely to occur in rapid eye movement sleep. And it seems to occur in this area, which has been called the hot zone, is active at the back part of the brain.
Mills: Let’s talk for a minute about how you study dreams because I know you work in a lab and people will come in and sleep and it sounds like you’ll wake them during the course of a night. How do you determine when you’re going to wake somebody what you’re going to ask them? And doesn’t that somehow bias in essence what’s happening? It’s different from if you were just at home in your own bed sleeping and maybe you had five dreams that night and you could tell them in the morning.
Blagrove: Yes, that’s very true. There is a level of bias there that can happen. The most famous one, and this was discovered in the early 1960s, is that if people are in the sleep lab and undergoing an experiment and their dreams are being collected, about a third of the dreams refer to being in the sleep lab. So the fact that you’re in the sleep lab does actually affect the content of the dreams. Now, it doesn’t affect the whole dream, thankfully. And so we don’t just get dreams which are solely about the sleep lab, but there is that what you could call contamination going on. And there is the possibility really that the natural course of a dream that would’ve occurred, as you’ve just said, if somebody was sleeping at home, doesn’t occur in the lab or doesn’t occur to such an extent in the lab.
But we do have an issue really of needing in the lab, of needing to work in the lab because that’s the way of making sure, for example, that you’ve got a REM sleep dream, a particular length, let’s say 10 minutes. You wait for the person to go into rapid eye movement sleep, and then you start the stopwatch going and then wake them say 10 minutes later or 5 minutes later. So from the point of view of getting the robust results, we have to be in the sleep lab. But that is correct, there can be some bias occurring.
Note the one thing which is that, for example, some of the studies we do, we wish to compare people’s REM dreams with their non-REM dreams. Of course, the person doesn’t know whether they’ve had a REM dream or a non-REM dream. So we can still do studies where we show them their dream and we get ratings of the dream, for example, such as of how long it was or how much emotion there is in it, or indeed for some of the studies we’ve done, how far away, how far back in their diaries they’ve been keeping does the dream refer to.
And what we find is that there’s a time course difference between REM and non-REM dreams on the memory sources for the dream. And in that instance, there’s less of a bias, I guess because you’re looking at someone’s REM and non-REM dreams and it’s only the experimenters that would know which dream is which.
Mills: Are there qualitative differences in REM and non-REM dreams?
Blagrove: Yes, there are qualitative differences. The non-REM dreams are shorter, they may have fewer emotions, fewer characters, fewer scenes, and there is a dispute, a debate goes on about that because if you control for the length of the dream in words, then short rapid eye movement, sleep dreams are very similar to long non rapid eye movement dreams. And so one theory says that actually the REM and non-REM dreams only differ in terms of how long they are, there’s that difference, and they don’t actually have any qualitative difference. They don’t really have any qualitative difference. As you get nearer to the end of the night, the non-REM dreams start to look more like REM dreams. They start to get longer, they start to get more bizarre and with more characters. And so there are all of these multitude of factors coming in that affect the dreams across the night.
Mills: Let’s talk about nightmares. What purpose do psychologists think they serve?
Blagrove: Yes, there’s a whole range of thoughts about nightmares. I mean there is the medical view, which is, and clinical psychology view, which is that nightmares are something that possibly need treating if the person is really distressed by them. There’s a method for doing that—imagery rehearsal therapy—in which the person imagines their nightmare and images their nightmare during the day with changed parts to it, and that decreases the number of nightmares that they have. And that type of approach to nightmares would see them as a disorder of sleep, much as apnea is a disorder of sleep or insomnia, say. And so would see it in terms of how do we reduce the number of nightmares that are occurring to a person.
There are then theories of nightmares. There’s one even that says that in nightmares, nightmares are beneficial to you because they’re the place where you practice the most severe threats to yourself. And it may be uncomfortable to the individual, but like pain, it’s actually useful. So there is an evolutionary theory of nightmares, which says that they are beneficial.
Another theory says that dreams in general have functions possibly to do with memory and is one possibility or emotion processing. And that when we have a nightmare, it’s been too much for the mind during the night. And so the nightmare is a sign that the function of dreaming has failed. So there are all those theories. There’s been an interesting recent paper about people who have more frequent nightmares react less to negative photographs that they’re shown when they’re awake. And one possibility there is that frequent nightmares attune people to nasty horrible images so that we’re less bothered by them when we’re awake. So there’s even that pro function view that nightmares have a function in that point of view.
Mills: How do you study nightmares? It seems like it wouldn’t be ethical to try to induce nightmares in a sleep lab. So how do you look at nightmares?
Blagrove: Yes, that’s true. It would almost certainly be unethical to actually cause someone to have nightmares. Yes. What’s usually done is naturalistic experiments. So there was for example, in 1989 an earthquake in California and people living in California was studied as a result of that. And it was found that the people in California were having many more nightmares than were people in Arizona. And they weren’t just having nightmares about earthquakes, but they were having nightmares in general. And so what you can do is get people who’ve been through a traumatic incident and study the increase in nightmares that results. Another possibility is rather than talking about extreme populations like that, is that some of the studies that we’ve done have been involved getting a large sample of people, say 200 people, asking them how often they have nightmares and correlating that with their levels of anxiety and depression and stress.
And what you find then is moderate correlations between anxiety, stress, depression, and having nightmares. So you can do studies in a naturalistic sense there that find out why some people have nightmares more than others. We’ve recently done work on a very, very interesting personality trait of sensory processing sensitivity that some people are highly sensitive persons and other people aren’t. And there’s a very interesting 27 items scale for measuring that. Elaine Aron was the divisor of that. And what we found is that being a highly sensitive person predisposes you to have nightmares if you are stressed, but if you are low on sensory processing sensitivity and you have stress, it doesn’t cause nightmares for them. So it’s a confound, it’s an interaction between sensory processing sensitivity. Some people are easily overwhelmed by stimuli and they jump at sounds and they’re possibly more thoughtful philosophical people. People who are highly sensitive persons if they’re put into a stressful situation, are more likely to respond with nightmares as a result.
Mills: Is dreaming unique to humans or do other animals dream as well?
Blagrove: Now that is interesting about what do animals do, because we’ve often, many people, and included with—my cats, you can see cats and dogs moving as if they’re trying to catch something. They do rhythmic movements or other type of movements during their sleep. So there is that type of circumstantial evidence that non-human animals might be having dreams that they’re reacting to during the night. That is very, very plausible. After all these animals quite possibly have a level of possibly even daydreaming, you could say, similar to us, or imagery going on similar to us. And so possibly it would seep over into their sleep to have dreams as well. There is a debate within child development literature on dreaming as to whether children have dreams which are quite like adults, bizarre dreams with lots of characters. For example. For example. Or do children—other findings are that children have very, very rudimentary dreams for the first few years of life, not really with other characters in or they may just dream about pets or animals or bodily states.
And from that point of view, which is the cognitive, neurocognitive view of dreaming, humans develop the skill of dreaming and we have to develop it up until the time when we’re in our teens. Now, from that point of view, if the neurocognitive people are correct, Bill Domhoff at University of California, Santa Cruz is one of the most famous ones for that, then you wouldn’t really expect animals to have very much more than rudimentary dreams because according to him and the neurocognitive point of view, even young children have very, very rudimentary dreams. So we can doubt that animals would have very much going on like that.
Mills: So you mentioned watching your cats when they’re sleeping and that they may move their legs as if they maybe are chasing something in their dream. I’m wondering about the issue of sleepwalking. I mean, we know people do that. How does sleepwalking relate to dreaming?
Blagrove: Yes. One of the interesting things about rapid eye movement sleep is that as well as the brain being very active during REM sleep and the eyes having these periodic bursts during the sleep is that our muscle tone is almost completely gone. So our lungs are still working and our hearts are still working, but very little else. And so what’s been found is that people sleep talk and sleepwalk during non-rapid eye movement sleep because that’s the time when the muscles that are needed to do that are working. The usual view is that the people who are sleep walking are not dreaming of what they’re they’re doing. That’s the usual there. And the usual view of sleep talking is similarly that the person is not having a dream which is related to the talking. The one exception to all of this is what’s called REM behavior disorder, which is really quite rare. But in that what’s called atonia, the lack of muscle tone that occurs during rapid eye movement, sleep is got rid of. And so the person can act out dreams and can actually sometimes act out quite violent dreams. And this sometimes gets to the notice of the authorities and criminal authorities because there is the possibility sometimes of violent acts being committed by somebody with REM behavior disorder, but that disorder is really quite rare, whereas sleepwalking and sleep talking are quite common non-REM conditions.
Mills: I want to talk a little bit about lucid dreaming, which is the dreams where people are aware that they’re dreaming and that they might even be able to influence what happens in the dream to a certain extent. What can you tell our audience about lucid dreaming? How does it happen? How common is it?
Blagrove: Yes. Lucid dreaming is really quite rare in that about half the population in Europe and North America have had a lucid dream once in their lifetime. And about 20% of the population have a lucid dream about once every month. And so they’re relatively rare. In the sleep lab, what’s been found is it’s about two to 3% of rapid eye movement sleep dreams are lucid dreams where somebody actually knows they’re dreaming and the dream continues. And so as well as knowing that it’s a dream they could, if they chose to, affect the content of the dream, that can affect the plot or introduce characters to the dream or, in a recent one that I had, decide to fly. So that can happen as well. So they are really quite, are quite rare, but very interesting when they do happen because they happen in rapid eye movement sleep, there is a view that the brain needs to be really quite active in order to have them.
They don’t really seem to occur in non-rapid eye movement sleep. And one of the main methods for inducing lucid dreams is to have the person wake up a couple of hours earlier than they would normally wake, get up, walk around, do things for an hour or two, and then go back to sleep for a nap. And because they’ve then delayed the second part of their sleep or the later part of their sleep, the brain is really quite active then. And so what’s found is that this what’s called Wake Back to Bed method is very good for inducing lucid dreams. The first thing is we seem to think it’s to do with a very active brain causing you to be lucid. The second thing is that some people may just sometimes notice that something is weird or incongruous in a dream and say, “ah, am I awake or am I dreaming?”
And indeed, there’s even a method developed around that which is a checking method, where people check reality in the daytime. They continually ask themselves, “am I dreaming?” and hopefully it can carry over into their dreams. So a combination of all those reasons cause people to have lucid dreams. Then there is a personality measure of internal locus of control, which we found is related to lucid dreams, internal locus of control. People believe that they’re in charge of their own life. They also believe that other people are quite in charge of their own lives as well – or ought to be. And people who are high on internal locus of control tend to have more lucid dreams. So it’s as if that personality feature creeps over into their dreams and causes them to be aware of dreaming and even wanting to control the dream.
Mills: Is it something that you can teach yourself though over time?
Blagrove: Yes, it can be taught if people are very interested in lucid dreams. Indeed, what can sometimes happen is people can hear about lucid dreams for the first time, so they know they exist. And that can cause people to start having a lucid dream because they know that they exist. Also, if people fall asleep wanting to have a lucid dream that can help them to have one, there’s the wake back to bed method that I’ve mentioned earlier on. And there’s now technological measures either in the sleep lab or you can buy these, in which for example, there’ll be a mask that’s put on the face and that detects whether your eyes are moving during sleep. And when the eyes are moving, it flashes red lights at you. And the red lights cause the dream to change either with—red objects come in or red goes towards the entire environment and the person may then realize that they’re dreaming and can then question, oh, I’m dreaming, and they know they’re having a lucid dream and the dream carries on as a lucid dream.
Mills: Now there are some things that we do in life that I think we just don’t tend to do in dreams. For example, I don’t think people do math in their dreams. What are some of the things that we do in our waking lives that we just don’t ever dream about?
Blagrove: Yes, that is interesting. There’s a very famous paper by Ernest Hartmann, who was a very major psychiatrist and dream researcher, and he wrote a paper in 1995 called, We Do Not Dream of the Three Rs. So we don’t dream of reading, writing, and arithmetic, and even though we spend a lot of the time doing those things in our waking life, they may just not be interesting enough to occur in our dreams, unless of course there’s some reason to have it there in the dream. So despite the fact that we spend so much time doing these things, they don’t show up in our dreams very much. Now the interesting thing there is though, that that was a sort of observational study that Ernest Hartmann did. If you actually want to do an experimental study to show that what’s emotional to you in waking life is more likely to come into your dreams, that’s really quite intricate to do that.
And so the way that that’s done is that, the way that various teams have done that, is to get people to keep a diary. And in the diary they record what’s happened to them during the day and the levels of emotion of what happens to them during the day. Then they record any dreams that they have. And what they do next is they’re asked to compare the diaries to their dreams and they’re asked, okay, what in the diary ended up in your dream? So the person is not allowed to say, “ah, this came from my dream.” I know where that’s from, but they hadn’t put it in the diary. This is very strictly and rigorously controlled, so you can only use the things that were in your diary. And what’s found then is that the items in diaries that tend go into dreams tend to be more emotional than the items in diaries that don’t go into the dream.
And so that’s in a way the evidence that we tend to dream of what’s emotional to us. We did a follow-up study to that at Swansea because those dreams in those studies were dreams that people reported at home. What we did in the Swansea sleep lab was we got people to keep a diary for 10 days, we then got them to sleep in the sleep lab and we then them compare their dreams to diaries. And what we found was that for REM dreams and non-REM dreams, if an item, items that were incorporated into dreams were significantly more emotional than items that were not incorporated into dreams, but if you had positive emotions, they were just as likely to go into your dreams as negative emotions. So as long as something is emotional, it’s got a good chance of getting into your dreams, whether it’s a positive emotion or a negative emotion. So that’s in a way shows the explanation for Ernest Hartmann’s finding that we don’t tend to dream of these mundane activities from our waking life.
Mills: Although I imagine if I were a mathematician, I would probably dream about math, but I’m not.
Blagrove: Yes, you may very well if something’s really meaningful to your life. I mean chess players, for example, may very well be indeed that’s something that is then not their mundane part of life, but could be really important to them, that they could then be dreaming of that. Indeed, yes.
Mills: So I have to ask you about this kind of longstanding myth. I think I heard it as a kid, that you can never dream that you’ve died because then you would die in your sleep. And as someone who has had such a dream in which I died, I know it’s not true. Where did these ideas come from?
Blagrove: Yes, indeed. There is a common belief, a folk belief that you can’t dream of dying in your dream and that if you do so, you may actually physically die. It’s a very interesting belief. Obviously scientifically it’d be very difficult to test for it because you may have various dead people, I’m sorry to be so gruesome about, you’d end up with various dead people and you’d have no way of knowing whether they had actually dreamt of dying just before they died. So notwithstanding the fact it’s very difficult to test this scientifically, I do wonder whether there are longstanding folk beliefs. There may even be famous stories even that were developed of, or horror films that were developed on the idea that if something that shocking occurred in your sleep, then it may actually cause you injury during your sleep. The Nightmare on Elm Street type of thing that if they dream of Freddy attacking them and scratching and stabbing their body, they wake up and it has actually physically happened to them.
So the idea that what could physically happen to you in your sleep can affect you physically is quite a longstanding one. And I guess you could even extrapolate it to dying. I mean, it may very well be that it’s—whereas we can imagine most things or vast numbers of things as daydreams. And so you can imagine, we can imagine vast number of things as dreams as well, that it may not be possible to have a dream about. It may not be possible to have a dream about dying because it’s such an awful thing to think about.
Mills: Well, let’s close with a question that I wanted to ask you, which is regarding dream deprivation. We know that sleep deprivation can be quite harmful to people’s health. What happens when people are deprived of the ability to dream?
Blagrove: Yes. When rapid eye movement sleep and its association with dreaming was found in the 1950s and early 1960s, there did start to be the theory that you needed to dream. And therefore that if people were deprived of the ability to dream, then somehow dreams would crop up elsewhere in psychosis or some type of fears or hallucinations, that type of thing. Now, the reason why that’s a little bit doubtful is because we do know that very many people just have very, very few dreams at all. It’s about 6% of people report absolutely never dreaming, and they could be woken in the lab and some of them do indeed have dreams, but we know that some people just seem to have no dreams at all, and we can’t quite see any deficit for them as a result of them not having the dreams. Now, it’s known that if people are deprived of rapid eye movement sleep, a very interesting phenomenon occurs, which is called REM rebound, which means that when they next go back to sleep, they don’t wait 90 minutes for the next rapid eye movement sleep period.
They try to get back into a REM period as quickly as possible. They try to get back into a REM period as quickly as possible. And so it’s as if people have an urge to have rapid eye movement sleep, and there may very well be biological reasons for that. We may be setting biochemicals in that state after the long trials of the day. There may be something to do with memory consolidation for rapid eye movement sleep. So it may very well be important, and that’s why we have rapid eye, rapid eye movement, sleep rebound. But whether the people are needing the REM sleep in order to have dreams and they’re having the rebound for that purpose is doubted, I think by most people because there seems to be enough biological reason to have your rapid eye movement sleep, let alone the fact that at the same time as the REM periods are occurring, you may very well be having dreams as well.
So it’s very difficult to deprive people of dreaming unless you actually physiologically deprive them of rapid eye movement sleep as well. So it’d be very difficult to work out whether or not, in fact, it’s the inability to have these images during the night that is causing them any problem. Now, of course, if the people who believe that have a function are correct, then there may indeed be some deficit to not having your dreams. It may indeed be that you’re not fully—one possibility is that we need to turn dreaming on and off during the night in order to finish with a burst of consciousness, our processing that’s going on during the night. So it may very well be that we do need our dreams for that final little bit of processing that’s occurring, but whether or not there’s actually a that would be seen if people didn’t have their dreams, there’s not really any evidence for that yet.
Mills: And so for those listeners who tend not to dream or remember their dreams, you’re okay.
Blagrove: You’re certainly okay. And Ernest Hartmann developed this scale, which is similar to in a way, to some of sensory processing sensitivity, which he called his boundary questionnaire. And there are thick-boundaried people who are sort of no-nonsense folks. They like to have stories with a beginning, a middle, and an end. They see the world in quite black and white, white. And then there are what he called the thin, more artistic types who are a bit more creative, possibly a bit more emotionally labile, possibly. And he pointed out that the thick boundary people, they may have fewer dreams, but we need the thick boundary people and we need the thin boundary people. We need the infrequent dreamers who may see themselves as more in touch with the world and with the physical world, and we need the more spontaneous dreamers as well. So it’s a sign of a diversity that we need all the different folks, the high and low dream recallers as well.
Mills: Well, Dr. Blagrove, I want to thank you for joining me today. This has been absolutely fascinating. I could go on for another hour, I’m sure.
Blagrove: Great. Thank you. It’s been very nice speaking to you as well, Kim. Thank you.
Mills: You can find previous episodes of Speaking of Psychology on our website at speakingofpsychology.org or on Apple, Spotify, YouTube, or wherever you get your favorite podcasts. And please leave us a review. If you have comments or ideas for future podcasts. You can email us at speakingofpsychology@apa.org. Speaking of Psychology is produced by Lea Winerman. Our sound editor is Chris Condayan.
Thank you for listening. For the American Psychological Association, I’m Kim Mills.
Whatever your dreams consist of, you’ve probably wondered where they come from and what they might be trying to tell you. Psychologists, too, have long studied the origin and purpose of dreams. Mark Blagrove, PhD, of Swansea University, talks about what we know—and don’t know—about why we dream; the relationship between our dreams and what’s happening in our waking life; why some dreams seem so common, like being unprepared for class or flying; why some people have particularly vivid and memorable dreams while others hardly dream at all; whether animals dream; and whether our dreams are entirely out of our conscious control or whether it’s possible to influence their content.
