Why do We Sleep and Dream?
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The exact functions of sleeping and dreaming are unknown, but psychologists have attempted to interpret what happens when we snooze. In this lesson, you'll explore the importance of sleep and some of the more famous theories regarding dreams.
We're going to talk about sleeping and dreaming and these are things that are regulated by what's known as a circadian rhythm. And what this basically means is it's the cycle that is sleeping and waking and then having that happen again. That's a rhythm - sleep, wake, sleep, wake - and it's called your circadian rhythm.
And there's some theories about why we sleep and what the actual thing that's going on when we sleep is, why we need to do it. There's a bunch of them. It's clear that there's a certain amount of body healing that goes on when we're sleeping. We're sort of fixing wounds and boosting our immune system and things like that. There's a bit about how memory is helped by sleeping, learning is helped by sleeping. We're going to go into that a little bit later in more detail.
But the field of sleep research doesn't really have a consensus on exactly what the function is, exactly why we do it, why we can't do these things when we're awake - that's something that no one exactly knows. One prominent sleep researcher was Dr. Dement. What he says about sleeping is, 'As far as I know, the only reason we need to sleep that is really really solid is because we get sleepy.' So that's Dr. Dement's take on it. And that just shows you that there's a lot of individual reasons we can identify, but we can't really identify why any of those have to take place while we're asleep and what the real unique function of sleep is.
But an aspect of sleep that has always fascinated psychologists is the dream aspect of it. What's going on? Why do we have dreams? What do they do? What do they mean? Do they mean anything? And the guy who really got us going with thinking about dreams is our favorite psychologist, Freud. Freud thought that dreams were basically wish fulfillment of our deepest, darkest desires going all the way back to childhood. So if your parents didn't give you that corn dog at the fair, it's going to come back in your dreams later on in life in horrible ways. That's what Freud basically thought.
And what he defined with what's going on in dreams is that you have two kinds of content. You have your manifest content and your latent content. Your manifest content is what actually is happening in your dreams. Let's say you had a dream about a giant oblong shape that is chasing you and it smells like a county fair - that would be your manifest content. Your latent content would be the fact that you're angry at your parents for not letting you have a corn dog. So the manifest content is actually in the dream, the latent content is what it means - the trauma, the desire, or thing that you want that inspired what the dream actually is.
So what Freud did was he raised dreaming's profile into something that we'd think about to study because before he came along, in the early 19th century, people pretty much thought that dreams were meaningless. They just didn't care about them that much. Freud was like, 'Ha! I know that they mean all these things.' He was probably not entirely right. There's no way to determine if he's right. It's just a theory.
More modern thinking about dreaming has kind of split into two basic approaches. Some scientists try to figure out the biology of what's going on when we're dreaming. And these are more in the computer science realm; these would be like hardware engineers, figuring out what's really going on about your brain while you're sleeping and dreaming. Others are going in a more psychological route. These are more like descendants of Freud in their thinking about dreams, but what they're really trying to do is work out how dreams help, hurt, or interact with our psyches. Not so much figuring out what happened to you traumatically as a kid. And these are more like software engineers. They're dealing with what's actually happening content-wise rather than what's happening hardware-wise.
So to understand dreams and their significance we want to look at both approaches. In the first approach (the biology one) the big revolutionary thing that happened was the discovery of REM sleep. This happened in the 1950s. REM sleep stands for rapid eye movement. If you ever watch someone while they sleep - that sounds really creepy, but I'm sure you've seen someone asleep at some point - you might have noticed rapid eye movement when they're dreaming. It looks like what it sounds; their eyes are closed and their eyes are flicking around underneath their lids. You can actually see this. Also, your dog or cat will do this, so if you don't want to creepily watch a human, you can just watch an animal and you'll see it too.
This is the time during your sleep cycle where your brain is the most activated in the most similar way to when you're awake. This is also the cycle in which you are having dreams. You get more and more REM sleep as the night goes along and you're more likely to wake up from a dream and remember it, essentially, toward the end of the night than you are at the beginning of the night.
And just a fun fact: you spend about two hours a night total in REM sleep, which is about six years over your lifetime. That's kind of scary. You're spending six years of your life dreaming about absurd things, at least if you're me.
A big deal was linking up dreams to this specific state of sleep that's going on. One of the more modern scientific theories about this that tries to figure out what exactly is going on during REM sleep is called the activation-synthesis theory. What this is trying to do is, again, figure out what's going on during REM sleep, and what it proposes is that your brain is generating random signals and during REM sleep, then you're interpreting these signals into patterns, into narratives, into what we experience as dreams. But it's just random brain activity that then gets converted into an experience of something that maybe doesn't make the most amount of sense, but makes more sense than you would think if you're just thinking that it's random brain activity.
The activation-synthesis theory has a lot of variance, but that's the basic idea - we're trying to create patterns out of randomness. It's like constellations; we see all these starts in the sky and make pictures out of them. That's really what's going on during REM sleep is that your random signals are being converted into coherent patterns. So that's the theory of why what's happening when we dream biologically.
Some biological theories try to get at the idea of why we dream or why we need to dream. One of the things they've turned up - I've mentioned briefly before that sleep can help with memory and learning - dreams can help with that as well. What scientists who've studied rats have learned is that if rats learn how to run a maze and they sleep and have REM sleep, they can see that various impulses that are happening in their brains are kind of the same as when they're running the maze and then when they're dreaming, essentially, about running the maze. This helps them learn to do it better the next day when they go in the maze place again.
So if you're studying for a test, you might dream not necessarily about the test, but you might dream in a way that reinforces the connections that you've made during your studying. Or you might have dreams about work that try to consolidate what you've learned or what you need to be doing. So this idea that dreams can help with memory consolidation and then, as a byproduct of that, we're learning new things.
I mentioned that you might have a dream about work as a quick example, but one of the big strictly psychological theories about why we dream and what it does is that they serve as a way of evaluating schemas or evaluating how we tend to organize our information. So if you had a nightmare about a new coworker, that might indicate that you've slotted that person or you've organized that person in a way that's not the best for you. Your dreams are helping you work out how you've organized your information and try to figure out how to do it better.
Also, some psychologists think that dreams are evolutionarily important in the sense that they give us a place to work out problems in a different state of mind - when we're asleep and we're dreaming. They let us deal with threats or with things that are scary or stressful. So again, that might explain your work dream as well.
More of our dreams that are proportional to the bad things that happen in our life are nightmares. The reason that some psychologists think this is is because it helps us deal with difficult things that happen in a safe space and in a space where you can try lots of different strategies without actually doing anything because you're asleep and you're not actually going to go out and do any of those things that might be destructive.
And it would have really been helpful for ancient humans who did actually have to run away from scary monsters a lot. If they were dreaming about running, about hiding, about doing things like that, that might actually help them in the world of predator and prey that we inhabited so long ago.
So you can see that in general, we've gone over a lot of different theories about why we sleep and dream. The whole process of sleeping and dreaming falls at a crossroads between biology and psychology because there's definitely biological reasons why we sleep and we dream - we repair the body, we consolidate our memories - and maybe a reason why we experience dreams the way we do is the activation-synthesis theory, which is that it's this random information formed into patterns by our brain while we dream during REM sleep. But there's also psychological reasons in that we might be rehearsing the way we categorize things. Or we might be dealing with threats, so if you dream about a tiger chasing you and then you maybe learn how to run away from tigers a little bit better while you're sleeping. But ultimately it's still an open question - why we sleep and why we dream and what they mean. No one really has a final word on it. It's something that's still open research and it's very exciting for that reason.