Understand and Use Dreams to Learn and Forget

**Andrew Huberman** (0:00)
Welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life.
I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. This podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire to bring you zero cost to consumer information about science and science-related tools. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink. I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or twice a day is that it helps me cover all of my basic nutritional needs. It makes up for any deficiencies that I might have. In addition, it has probiotics, which are vital for microbiome health. I've done a couple of episodes now on the so-called gut microbiome and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With Athletic Greens, I get the vitamins I need, the minerals I need and the probiotics to support my microbiome. If you'd like to try Athletic Greens, you can go to athleticgreens.com/huberman and claim a special offer. They'll give you five free travel packs plus a year supply of vitamin D3 K2. There are a ton of data now showing that vitamin D3 is essential for various aspects of our brain and body health. Even if we're getting a lot of sunshine, many of us are still deficient in vitamin D3. And K2 is also important because it regulates things like cardiovascular function, calcium in the body and so on. Again, go to athleticgreens.com/huberman to claim the special offer of the five free travel packs and the year supply of vitamin D3 K2. Today's episode is also brought to us by Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the exact ratios of electrolytes are an element and those are sodium, magnesium and potassium, but it has no sugar. I've talked many times before on this podcast about the key role of hydration and electrolytes for nerve cell function, neuron function, as well as the function of all the cells and all the tissues and organ systems of the body. If we have sodium, magnesium and potassium present in the proper ratios, all of those cells function properly and all our bodily systems can be optimized. If the electrolytes are not present and if hydration is low, we simply can't think as well as we would otherwise. Our mood is off, hormone systems go off, our ability to get into physical action, to engage in endurance and strength and all sorts of other things is diminished. So with element, you can make sure that you're staying on top of your hydration and that you're getting the proper ratios of electrolytes. If you'd like to try element, you can go to drink element, that's lmnt.com/huberman, and you'll get a free element sample pack with your purchase. They're all delicious. So again, if you want to try element, you can go to element, lmnt.com/huberman.
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Take a three-minute quiz, and Thesis will send you four different formulas to try in your first month. That's takethesis.com/huberman, and use the code Huberman at checkout for 10% off your first order. Today, we're going to talk about dreaming, learning during dreaming, and unlearning during dreaming. In particular, unlearning of troubling emotional events. Now, my interest in dreaming goes way back. When I was a child, I had a friend and he came over one day and he brought with him a mask that had a little red light in the corner. He had purchased this thing through some magazine ad that he had seen. And this mask was supposed to trigger lucid dreaming. Lucid dreaming is the experience of dreaming during sleep, but being aware that one is dreaming. And in some cases, being able to direct one's dream activities. So if you're in a lucid dream and you want to fly, for instance, some people report being able to initiate that experience of flying or to contort themselves into an animal or to transport themselves to wherever they want within the dream. I tried this device. The way it worked is you put on the mask during the waking state, wide awake, and you'd look at the little light flashing in the corner. And then you'd also wear it when you went to sleep at night. And indeed, while I was asleep, I could see the red light, presumably through my eyelids, although for all I know, I had opened my eyes, I don't know, I was asleep. And then because I was dreaming and I was experiencing something very vivid, I was able to recognize that I was dreaming and then start to direct some of the events within that dream. Now, lucid dreaming occurs in about 20% of people, and in a small percentage of those people, they lucid dream almost every night. So much so that many of them report their sleep not being as restorative as it would be otherwise. Now, all of this is to say that lucid dreaming and dreaming are profound experiences. We tend to feel extremely attached to our dream experience. This may explain the phenomenon of people who have a very intense dream, they need to somehow tell everybody about that dream or tell someone about that dream. I don't really know what that behavior is about, but sometimes we wake up and we feel so attached to what happened in this state that we call dreaming that there seems to be an intense need to share it with other people, presumably to process it and make sense of it. Now, numerous people throughout history have tried to make sense of dreams in some sort of organized way, the most famous of which of course is Sigmund Freud who talked about symbolic representations in dreams. A lot of that has been kind of debunked, although I think that there's some interest in what the symbols of dreaming are. And this is something that we'll talk about in more depth today, although not Freudian theory in particular. So I think in order to really think about dreams and what to do with them and how to maximize the dream experience for sake of learning and unlearning, the best way to address this is to look at the physiology of sleep. To really just, what do we know concretely about sleep? So first of all, as we get sleepy, we tend to shut our eyes. And that's because there are some autonomic centers in the brain, some neurons that control closing of the eyelids when we get sleepy. And then we transition into sleep. And sleep, regardless of how long we sleep, is generally broken up into a series of 90 minute cycles, these Ultradian cycles. So early in the night, these 90 minute cycles tend to be comprised more of shallow sleep and slow wave sleep. So stage one, stage two, et cetera, and what we call slow wave sleep. I'll go into detail about what all this means in a moment. And we tend to have less so-called REM sleep, R-E-M sleep, which stands for rapid eye movement sleep. And I'll talk about rapid eye movement sleep in detail. So early in the night, a lot more slow wave sleep and less REM. For every 90-minute cycle that we have during a night of sleep, we tend to start having more and more REM sleep. So more of that 90-minute cycle is comprised of REM sleep and less of slow wave sleep. Now this is true regardless of whether or not you wake up at the middle of the night to use the restroom or your sleep is broken. The more sleep you're getting across the night, the more REM sleep you're going to have. And REM sleep and non-REM, as I'll refer to it, have distinctly different roles in learning and unlearning. And they are responsible for learning and unlearning of distinctly different types of information. And this has enormous implications for learning of motor skills, for unlearning of traumatic events or for processing emotionally challenging as well as emotionally pleasing events. And as we'll see, one can actually leverage their daytime activities in order to access more slow-wave sleep or non-REM sleep as we'll call it, or more REM sleep, depending on your particular emotional and physical needs. So it's really a remarkable stage of life that we have a lot more control and power over than you might believe. We'll also talk about lucid dreaming. We're also going to talk about hallucinations and how drug induced hallucinations have a surprising similarity to a lot of dream states and yet some really important differences. Okay, so let's start by talking about slow wave sleep or non-REM sleep. Now I realize that slow wave sleep and non-REM sleep aren't exactly the same thing. So for you sleep aficionados out there, I am lumping right now, as we say in science, there are lumpers and there are splitters and I am both. Sometimes I lump, sometimes I split. For sake of clarity and ease of conversation right now, I'm going to be a lumper. So when I say slow wave sleep, I mean non-REM sleep generally. Although I acknowledge there is a distinction. Slow wave sleep. So slow wave sleep is characterized by a particular pattern of brain activity in which the brain is metabolically active, but that there's these big sweeping waves of activity that include a lot of the brain. If you want to look this up there, you can find evidence for sweeping of waves of neural activity across association cortex, across big swaths of the brain stem, the so-called pons, geniculate, occipital pathway. This is brain stem, thalamus and then cortex for those of you that are interested, although more of that is going to occur in REM sleep. Now, the interesting thing about slow wave sleep are the neuromodulators that tend to be associated with it that are most active and least active during slow wave sleep. And here's why. To remind you, neuromodulators are these chemicals that act rather slowly but their main role is to bias particular brain circuits to be active and other brain circuits to not be active. These are like the music playlist. So think of neuromodulators and these come in the names of acetylcholine, norepinephrine, serotonin and dopamine. Think of them as suggesting playlists on your audio device. So, you know, classical music is distinctly different in feel and tone and a number of other features from like third wave punk or from, you know, hip hop, right? So think of them as biasing toward particular genres of neural circuit activity, okay? Mellow music versus really aggressive fast music or rhythmic music that includes lyrics versus rhythmic music that doesn't include lyrics. That's more or less the way to think about these neuromodulators. And they are associated as a consequence with certain brain functions. So we know, for instance, and just to review, acetylcholine in waking states is a neuromodulator that tends to amplify the activity of brain circuits associated with focus and attention. Norepinephrine is a neuromodulator that tends to amplify the brain circuits associated with alertness and the desire to move. Serotonin is the neuromodulator that's released and tends to amplify the circuits in the brain and body that are associated with bliss and the desire to remain still. And dopamine is the neuromodulator that's released and is associated with amplification of the neural circuits in the brain and body associated with pursuing goals and pleasure and reward, okay? So in slow wave sleep, something really interesting happens. There's essentially no acetylcholine. Acetylcholine production and release and action from the two major sites, which are in the brainstem, which from a nucleus, if it's a parabi-geminal nucleus, if you really want to know, or from the forebrain, which is nucleus basalis, and you don't need to know these names, but if you like, that's why I put them out there. Acetylcholine production plummets. It's just almost to zero. And acetylcholine, as I just mentioned, is associated with focus. So you can think of slow wave sleep as these big sweeping waves of activity through the brain and a kind of distortion of space and time so that we're not really focusing on any one thing. Now, the other molecules that are very active at that time are norepinephrine, which is a little bit surprising because normally in waking states, norepinephrine is going to be associated with a lot of alertness and the desire to move, but there's not a ton of norepinephrine around in slow wave sleep, but it is around. So there's something associated with the movement circuitry going on in slow wave sleep. And remember, this is happening mostly at the beginning of the night. Your sleep is dominated by slow wave sleep. So no acetylcholine, very little norepinephrine, although there is some, and a lot of serotonin. And serotonin again is associated with this desire, the sensation of kind of bliss or well-being, but not a lot of movement. And during sleep, you tend not to move. Now in slow wave sleep, you can move. You're not paralyzed, so you can roll over. If people are going to sleepwalk, typically it's going to be during slow wave sleep. And what studies have shown through some kind of sadistic experiments where people are deprived specifically of slow wave sleep, and that can be done by waking them up as soon as the electrode recordings show that they're in slow wave sleep, or by chemically altering their sleep so that it biases them away from slow wave sleep. What studies have shown is that motor learning is generally occurring in slow wave sleep. So let's say the day before you go to sleep, you were learning some new dance move, or you were learning some specific motor skill, either a fine motor skill or a coarse motor skill. So let's say it's a new form of exercise or some new coordinated movements. This could be coordinated movement at the level of the fingers, or it could be coordinated movement at the level of the whole body and large limb movements. It could involve other people or it could be a solo activity. Learning of those skills is happening primarily during slow wave sleep in the early part of the night. In addition, slow wave sleep has been shown to be important for the learning of detailed information. Now this isn't always cognitive information. We're going to talk about cognitive information, but the studies that have been done along these lines involve having people learn very detailed information about very specific rules and the way that certain words are spelled. They tend to be challenging words. So if people are tested in terms of their performance on these types of exams and they're deprived of slow wave sleep, they tend to perform very poorly. So we can think of slow wave sleep as important for motor learning, motor skill learning, and for the learning of specific details about specific events. And this turns out to be fundamentally important because now we know that slow wave sleep is primarily in the early part of the night and motor learning is occurring primarily early in the night and detail learning is occurring early in the night. Now for those of you that are waking up after only three, four hours of sleep, this might be informative. This might tell you a little something about what you are able to learn and not able to learn if that were to be the only sleep that you get. Although, hopefully, that's not the only sleep that you get. But we're going to dive deep into how it is that one can maximize motor learning in order to extract, say, more detail information about coordinated movements and how to make them faster or slower. So that might be important for certain sports. That might be almost certainly important for certain sports. It's going to be important for any kind of coordinated movement, like say learning to play the piano or, for instance, how to learn synchronized movements with somebody else. So maybe I mentioned the example of dance earlier. If you, like me, a few years ago, I set out to learn tango because I have some Argentine relatives and I was abysmal. I need to return to that at some point. I was just abysmal. And one of the worst things about being abysmal at learning dance is that somebody else has to suffer the consequences also. So, I don't know, maybe in the month on neuroplasticity, I'll explore that again as a self-experimentation. But the key things to know are slow wave sleep involved in motor learning and detailed learning. There's no acetylcholine around at that time. Has this big amplitude activity sweeping throughout the brain and that there's the release of these neuromodulators, norepinephrine and serotonin. And again, that's all happening early in the night. So, athletes, people that are concerned about performance, if you happen to wake up after just a couple hours of, you know, three, four hours of sleep, because you're excited about a competition the next day, presumably, if you've already trained the skills that you need for the event, you should be fine to engage in that particular activity. Now, it's always going to be better to get a full night sleep. And you know, a full night sleep for you is six hours, then it's always going to be better to get more sleep than it is to get less. However, I think some people get a little bit overly concerned that if they didn't get their full night sleep before some sort of physical event, that their performance is going to plummet. Presumably, if you've already learned what you need to do and it's stored in your neural circuits and you know how to make those coordinated movements, what the literature on slow wave sleep suggests is that you would be replenished, that the motor learning and the recovery from exercise is going to happen early in the night. So we'll just pause there and kind of shelve that for a moment and then we're going to come back to it. But I want to talk about REM sleep or rapid eye movement sleep. REM sleep and rapid eye movement sleep, as I mentioned before, occurs throughout the night, but you're going to have more of it. A larger percentage of these 90 minute sleep cycles is going to be comprised of REM sleep as you get toward morning. REM sleep is fascinating. It was discovered in the 50s when a sleep laboratory in Chicago, the researchers observed that people's eyes were moving under their eyelids. Now, something very important that we're going to address when we talk about trauma later is that the eye movements are not just side to side, they're very erratic in all different directions. One thing that I don't think anyone, I've never heard anyone really talk about publicly is why eye movements during sleep. I think eyes are closed and sometimes people's eyelids will be a little bit open and their eyes are darting around, especially in little kids. I don't suggest you do this. I'm not even sure it's ethical, but it has been done where you pull back the eyelids of a kid while they're sleeping and their eyes are kind of darting all over the place. I think people do this to their passed out friends at parties and things like that. So again, I don't suggest you do it, but I'm tell you it because it's been done before and therefore you don't have to do it again. But rapid eye movement sleep is fascinating and occurs because there are connections between the brain stem, an area called the pons and areas of the thalamus and the top of the brain stem that are involved in generating movements in different directions, sometimes called saccades. Although sometimes during rapid eye movement sleep, it's not just rapid, it's kind of a jittery side to side thing and then the eyeballs kind of roll. It's really pretty creepy to look at if you see. So what's happening there is the circuitry that is involved in conscious eye movements is kind of going haywire, but it's not haywire. It's these waves of activity from the brainstem up to the so-called thalamus, which is an area that filters sensory information and then up to the cortex. And the cortex of course is involved in conscious perceptions. So in rapid eye movement sleep, there are a couple of things are happening besides rapid eye movements. The main ones are that they're in, I should say in contrast to slow wave sleep. In REM sleep, serotonin is essentially absent. Okay, so this molecule, this neuromodulator, that tends to create the feeling of bliss and well-being and just calm placidity is absent. All right, so that's interesting. In addition to that, norepinephrine, this molecule that's involved in movement and alertness is absolutely absent. It's probably one of the few times in our life that epinephrine is essentially at zero activity within our system. And that has a number of very important implications for the sorts of dreaming that occur during REM sleep and the sorts of learning that can occur in REM sleep and unlearning. First of all, in REM sleep, we are paralyzed. We are experiencing what's called atonia, which just means that we're completely laid out and paralyzed. We also tend to experience whatever it is that we're dreaming about as a kind of hallucination or a hallucinatory activity.