WEBVTT 00:00:00.000 --> 00:00:04.528 Welcome to Huberman Lab Essentials, where we revisit past episodes for the most 00:00:04.611 --> 00:00:09.023 potent and actionable science-based tools for mental health, physical health, 00:00:09.106 --> 00:00:10.040 and performance. 00:00:11.360 --> 00:00:15.440 I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology 00:00:15.524 --> 00:00:19.777 at Stanford School of Medicine. And now for my discussion with Dr. Gina Poe. 00:00:19.860 --> 00:00:23.498 Dr. Gina Poe, welcome. - Thank you. - I've really been looking forward to 00:00:23.581 --> 00:00:27.627 this conversation. I know that many people are going to be excited to learn about 00:00:27.710 --> 00:00:31.960 your work. as it relates to sleep, as it relates to problem solving, creativity, 00:00:32.043 --> 00:00:34.080 and a number of other important topics. 00:00:34.410 --> 00:00:38.750 To start things off, I would love for you to educate us a bit about this thing 00:00:38.833 --> 00:00:42.379 that we are all familiar with and yet very few of us understand, 00:00:42.462 --> 00:00:46.575 which is sleep. Could you describe the various phases of sleep that exist? 00:00:46.658 --> 00:00:48.870 What distinguished them? And perhaps... 00:00:49.110 --> 00:00:53.185 Frame this within the context of what would a perfect night's sleep look like? 00:00:53.268 --> 00:00:56.916 All right. So sleep is really different from wakefulness and, in fact, 00:00:56.999 --> 00:01:00.861 can't be replaced by any state of wakefulness that we've been able to come 00:01:00.944 --> 00:01:04.059 up with so far. Our brain chemistry is completely different. 00:01:04.142 --> 00:01:06.938 And in the different stages of sleep, which there are, 00:01:07.021 --> 00:01:09.763 is non-REM and REM are the two major states of sleep. 00:01:09.846 --> 00:01:13.068 Those two states are entirely different from one another, too. 00:01:13.151 --> 00:01:15.710 And even within non-REM, there are three states. 00:01:19.110 --> 00:01:20.110 falling asleep. 00:01:21.230 --> 00:01:24.509 There's kind of an interesting rhythm that goes on in the brain. 00:01:24.593 --> 00:01:27.714 It's kind of a fast gamma rhythm. And then there's stage two, 00:01:27.798 --> 00:01:31.970 which is a really cool state. We sort of used to ignore sleep researchers because 00:01:32.053 --> 00:01:35.595 it was a transient state between wakefulness and the deep stage three 00:01:35.679 --> 00:01:38.643 slow-wave sleep, which is the most impressively different, 00:01:38.726 --> 00:01:41.427 which is when big slow waves sweep through our brain, 00:01:41.511 --> 00:01:43.739 and now we realize that it cleans our brain. 00:01:43.822 --> 00:01:47.290 One of the things that those big slow waves do is cleans our brain 00:01:50.310 --> 00:01:52.969 us from a day of wakefulness. And then REM sleep, 00:01:53.053 --> 00:01:57.336 which is the most popular because that's where we have the most active dreams. 00:01:57.419 --> 00:01:59.686 When you wake up someone out of REM sleep, 00:01:59.770 --> 00:02:03.549 they'll almost always report having dreamed something really bizarre. 00:02:03.632 --> 00:02:06.347 That's called REM sleep, rapid eye movement sleep. 00:02:06.431 --> 00:02:09.370 So those are the four states of sleep, of human sleep. 00:02:09.453 --> 00:02:13.792 And we cycle through them every 90 minutes or so. And then we start over again. 00:02:13.876 --> 00:02:17.290 And we have about five of those per night for a perfect night 00:02:20.310 --> 00:02:23.354 A perfect night's sleep is seven and a half, eight hours. 00:02:23.437 --> 00:02:26.017 And what about the sleep where we are lightly... 00:02:26.100 --> 00:02:31.152 asleep. And we might have a dream that has us somehow thinking about movement or 00:02:31.235 --> 00:02:35.902 that we jolt ourselves awake. That often happens early in the night. Yeah. 00:02:35.985 --> 00:02:39.946 Yeah. That's the first stage, stage one and stage two of sleep. 00:02:40.029 --> 00:02:45.274 And stage two sleep is really cool because that has something called sleep spindles 00:02:45.357 --> 00:02:50.300 and K complexes. And what sleep spindles are, are a little of activity that's 00:02:56.100 --> 00:02:58.745 The gathalamus is the gateway to consciousness, 00:02:58.828 --> 00:03:01.415 and the neocortex processes all our cognition. 00:03:01.499 --> 00:03:05.363 And if you wake up out of that state, you will often report a dream, 00:03:05.446 --> 00:03:10.181 like a hallucination-style dream. It won't be a long dream report like you have out 00:03:10.264 --> 00:03:13.315 of REM sleep, but it will be some hallucination state. 00:03:13.399 --> 00:03:18.017 Are they quite different than the patterns of sleep and dreaming that occur later 00:03:18.100 --> 00:03:19.900 in the night or toward morning? 00:03:26.100 --> 00:03:32.039 processing. And in fact, if you've learned something new that day or have experienced 00:03:32.122 --> 00:03:37.495 a new sensory motor experience, then your early sleep dreams will incorporate 00:03:37.578 --> 00:03:41.817 that experience much more than the later sleep dreams. Later, 00:03:41.900 --> 00:03:45.997 as that memory gets consolidated from the early structures, 00:03:46.080 --> 00:03:51.007 which are the hippocampus deep in the temporal lobe to the cortex in a 00:03:51.090 --> 00:03:56.761 distributed fashion, that memory seems to move from that hippocampus to the cortex, 00:03:56.844 --> 00:04:02.168 and also the dreams that incorporate that memory also move later in the night. 00:04:02.252 --> 00:04:04.470 So there was a great study by... 00:04:04.740 --> 00:04:09.239 Siddhartha Ribeiro, who studied the consolidation of memories from 00:04:09.322 --> 00:04:14.460 the hippocampus to the cortex in a rat across the period of a full period. 00:04:15.060 --> 00:04:17.978 day's sleep because rats sleep in the daytime. 00:04:18.061 --> 00:04:22.740 And he found that each subsequent REM sleep period moved that memory from 00:04:22.824 --> 00:04:26.263 the hippocampus to the first area that projects to it, 00:04:26.347 --> 00:04:29.525 and then the second area, and then the third area. 00:04:29.609 --> 00:04:33.113 And you can see the memory moving throughout the sleep. 00:04:33.197 --> 00:04:38.006 There's a number of different hormones associated with the different stages 00:04:38.090 --> 00:04:43.226 of sleep. We know that melatonin is a hormone of nighttime that makes us sleepy. 00:04:43.309 --> 00:04:47.739 What about growth hormone release? When does that occur during sleep? 00:04:47.822 --> 00:04:51.979 So growth hormone release happens all day long and all night long. 00:04:52.062 --> 00:04:57.439 But the deep, slow-wave sleep that you get the very first sleep cycle is when you get 00:04:57.523 --> 00:05:01.486 a big bolus of growth hormone release in men and women equally. 00:05:01.570 --> 00:05:03.240 And if you miss that first 00:05:03.570 --> 00:05:08.739 deep slow asleep period you also miss that big bolus of growth hormone release. 00:05:08.823 --> 00:05:13.992 And you might get ultimately across the day just as much overall growth hormone 00:05:14.075 --> 00:05:19.444 release, but androchronologists will tell you that big boluses do different things 00:05:19.528 --> 00:05:24.431 than a little bit eked out over time. There's also a big push to synthesize 00:05:24.514 --> 00:05:26.110 proteins. So that's when 00:05:26.280 --> 00:05:31.650 the protein synthesis part that builds memories for example in our brain happens 00:05:31.734 --> 00:05:35.277 in that first cycle of sleep. So you don't want to miss that, 00:05:35.360 --> 00:05:39.850 especially if you've learned something really big and needs more synaptic space 00:05:39.933 --> 00:05:43.323 to encode it. How would somebody miss that first 90 minutes? 00:05:43.406 --> 00:05:47.837 Sleep depriving themselves. Yeah. So let's say I normally go to sleep at 10 PM 00:05:47.921 --> 00:05:51.310 and then from 10 to 1130 would be this first phase of sleep. 00:05:51.394 --> 00:05:55.130 And that's when the big bolus of growth hormone would be released. 00:05:55.214 --> 00:05:59.645 Does that mean that if I go to sleep instead at 1130 or midnight that I missed 00:05:59.728 --> 00:06:00.562 that 00:06:02.640 --> 00:06:04.237 I get that first phase of sleep. 00:06:04.320 --> 00:06:09.759 just simply starting later. Every cell in our body has a clock and all those 00:06:09.842 --> 00:06:14.420 circadian clocks are synchronized and so our cells are ready to 00:06:14.550 --> 00:06:19.106 respond to that growth hormone release at a particular time. And if we miss it, 00:06:19.189 --> 00:06:23.275 and it's a time in relation to melatonin also, so if you miss it, yeah, 00:06:23.359 --> 00:06:25.742 you might get some growth hormone release, 00:06:25.825 --> 00:06:30.498 but it's occurring at a time when your clock has already moved to the next phase. 00:06:30.581 --> 00:06:35.494 And so... It's just a clock thing. So what this means is that we should have fairly 00:06:35.577 --> 00:06:39.358 consistent bedtimes in addition to fairly consistent wake times. 00:06:39.442 --> 00:06:44.249 Is that right? Exactly. And in fact, one of the best markers of good neurological 00:06:44.332 --> 00:06:47.230 health when we get older is consistent bedtimes. 00:06:47.820 --> 00:06:51.063 I'd like to take a quick break and acknowledge one of our sponsors, 00:06:51.146 --> 00:06:55.085 Element. Element is an electrolyte drink that has everything you need and nothing 00:06:55.168 --> 00:06:57.964 you don't. 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Are there things that I perhaps do in the preceding hours of 00:08:28.091 --> 00:08:30.587 the preceding day, like ingest caffeine or alcohol, 00:08:30.670 --> 00:08:33.369 that can make that first stage of sleep less effective, 00:08:33.452 --> 00:08:35.594 even if I'm going to sleep at the same time? 00:08:35.677 --> 00:08:39.387 Alcohol definitely will do that because alcohol is a REM sleep suppressant, 00:08:39.470 --> 00:08:43.433 and it even suppresses some of that stage two transition to REM with those sleep 00:08:43.516 --> 00:08:47.360 spindles. And those sleep spindles, we didn't talk about their function yet, 00:08:50.100 --> 00:08:53.461 to our cortex. It's a unique time when our hippocampus, 00:08:53.544 --> 00:08:57.280 sort of like the RAM of our brains, writes it to a hard disk, 00:08:57.364 --> 00:09:01.476 which is the cortex. And it's a unique time when they're connected. 00:09:01.559 --> 00:09:05.734 So if you don't want to miss that, you don't want to miss REM sleep, 00:09:05.817 --> 00:09:09.679 which is also a part of the consolidation process. And alcohol, 00:09:09.762 --> 00:09:14.876 before we go to sleep, will do that. Until we've metabolized alcohol and put it out 00:09:14.960 --> 00:09:17.840 of our bodies, it will affect our sleep badly. 00:09:19.890 --> 00:09:24.026 90-minute blocks of sleep. Is there anything that makes those unique? 00:09:24.110 --> 00:09:28.674 What is their signature, besides the fact that they come second and third in 00:09:28.757 --> 00:09:32.955 the night? There's more and more REM sleep the later the night we get. 00:09:33.038 --> 00:09:37.725 There's also a change in hormones, the growth hormone and melatonin levels are 00:09:37.808 --> 00:09:41.089 starting to decline, but other hormones are picking up. 00:09:41.172 --> 00:09:46.103 So it is a really different stage that you also don't want to shortchange yourself 00:09:46.187 --> 00:09:47.020 on. 00:09:49.890 --> 00:09:55.041 times in sleep when the most creativity can happen that's when our dreams can 00:09:55.124 --> 00:09:59.927 incorporate and put together old and new things together into a new way 00:10:00.010 --> 00:10:02.500 and our schema are built during that time. 00:10:02.584 --> 00:10:07.096 So that's when your computer of your brain is opening folders and comparing 00:10:07.180 --> 00:10:10.038 documents, seeing if there is anything the same. 00:10:10.121 --> 00:10:12.734 These two documents look very much the same, 00:10:12.817 --> 00:10:17.698 but there's a little bit of difference. And it can it can link those conceptually 00:10:17.781 --> 00:10:22.784 so that that's probably one of the origins of creativity is finding things that are 00:10:22.867 --> 00:10:27.747 related, maybe just linked a little bit and you can find that link and strengthen 00:10:27.831 --> 00:10:32.775 it if it works. makes your schema interesting and different. Many people, 00:10:32.858 --> 00:10:35.080 including myself, tend to wake up 00:10:35.380 --> 00:10:38.434 maybe once during the middle of the night to use the restroom. 00:10:38.517 --> 00:10:41.115 I've tried to drink less fluid before going to sleep. 00:10:41.198 --> 00:10:45.163 I've heard also the impulse to urinate is also dictated by how quickly you drink 00:10:45.246 --> 00:10:49.210 fluid, not just the total volume. So I've switched to sipping fluids more slowly 00:10:49.294 --> 00:10:51.892 for my last beverage of the day, which seems to help. 00:10:51.975 --> 00:10:55.130 Is there any known detriment to this middle of the night waking, 00:10:55.213 --> 00:10:59.127 or should we consider it a normal feature for some people's sleep architecture? 00:10:59.210 --> 00:11:00.044 Yeah, I think we 00:11:05.380 --> 00:11:09.259 And so really don't worry about how much you're sleeping as long as you're not 00:11:09.342 --> 00:11:13.170 intentionally depriving yourself of sleep by doing something really rewarding 00:11:13.253 --> 00:11:16.878 and exciting because even that is stressful to your body and deprives you 00:11:16.961 --> 00:11:20.720 of a lot of things we're talking about. It's absolutely normal to wake up. 00:11:21.040 --> 00:11:24.432 at least once in the middle of the night to go to the bathroom. 00:11:24.515 --> 00:11:28.403 And as long as you can get back to sleep in a reasonable amount of time, 00:11:28.486 --> 00:11:31.381 or even if it takes you an hour, don't worry about it. 00:11:31.465 --> 00:11:35.463 As long as you have a lifestyle that allows you to then make up that sleep 00:11:35.546 --> 00:11:39.489 either the next morning or the next night, going to bed a little earlier. 00:11:39.573 --> 00:11:43.516 What is unique perhaps about the architecture of dreams and sleep in the, 00:11:43.599 --> 00:11:47.460 let's say the last third of the night or the second half of the night? 00:11:51.040 --> 00:11:55.867 and those are... Considered the deepest sleep, even though slow-wave sleep, 00:11:55.951 --> 00:11:58.523 big slow-wave is considered deep. It is deep. Yeah, 00:11:58.607 --> 00:12:01.909 they call slow-wave sleep deep sleep and REM sleep rapid-odemium, 00:12:01.992 --> 00:12:05.554 but now you're telling me that REM sleep is actually the deeper sleep. 00:12:05.638 --> 00:12:09.513 The reason why you call slow-wave sleep deep sleep is because it's difficult 00:12:09.596 --> 00:12:13.783 to arouse people out of that state. And when you do arouse them out of that state, 00:12:13.866 --> 00:12:17.898 they're most often confused and just want to go back into sleep and can go back 00:12:17.981 --> 00:12:18.814 pretty easily. 00:12:22.930 --> 00:12:26.303 really kind of almost like wakefulness. It was so vivid. 00:12:26.386 --> 00:12:30.993 And maybe one of the reasons why REM sleep is deeper is especially in adults 00:12:31.076 --> 00:12:35.560 and older people that deep slow wave sleep goes away. So it's not as deep. 00:12:35.643 --> 00:12:40.435 It's not as big. The slow waves aren't as large, which is probably problematic, 00:12:40.518 --> 00:12:44.693 but we are not sure. And so then REM sleep becomes the deepest stage. 00:12:44.776 --> 00:12:47.430 We are paralyzed during REM sleep, correct? 00:12:52.930 --> 00:12:56.041 dreaming storyline dreams and we could hurt ourselves. 00:12:56.125 --> 00:13:00.715 We're actually really cut off from the outside world in terms of responding to, 00:13:00.798 --> 00:13:04.856 say, this table or window or door. And so different from sleepwalking, 00:13:04.939 --> 00:13:08.405 which is out of slow-wave sleep. And out of slow-wave sleep, 00:13:08.489 --> 00:13:12.014 that sleepwalking is a mixture between sleep and wakefulness. 00:13:12.097 --> 00:13:16.628 You can cook a full meal, drive your car while you're in deep slow-wave sleep. 00:13:16.711 --> 00:13:21.030 It's scary because you never know what you're going to do. You don't have 00:13:22.930 --> 00:13:26.327 over it. You have no conscious control over it. But you can actually... 00:13:26.410 --> 00:13:30.603 safely navigate some situations in sleepwalking and actually have 00:13:30.687 --> 00:13:35.735 a conversation, although it may not make much sense when you're sleep talking. 00:13:35.819 --> 00:13:37.990 In REM sleep, you're not going to 00:13:38.110 --> 00:13:43.165 processing the outside world. And instead, when you're acting out your dreams, 00:13:43.248 --> 00:13:48.304 you could be doing things like walking through a plate glass window or falling 00:13:48.387 --> 00:13:51.729 off of, you know, down the stairs, things like that. 00:13:51.813 --> 00:13:54.250 So you really want your muscles to be 00:13:54.460 --> 00:13:58.786 inactivated during REM sleep. Otherwise, you will act out those dreams and really 00:13:58.869 --> 00:14:00.720 hurt yourself or your bed partner. 00:14:01.240 --> 00:14:02.357 So as I. 00:14:02.440 --> 00:14:07.095 people start to approach morning or the time when they normally would wake up. 00:14:07.178 --> 00:14:09.949 I've heard that it's important to, if possible, 00:14:10.033 --> 00:14:14.019 complete one of these 90-minute cycles prior to waking up. That is, 00:14:14.103 --> 00:14:18.939 if you set your alarm for halfway through one of these 90-minute cycles that come 00:14:19.023 --> 00:14:23.859 late in the night of sleep, that it can lead to rather groggy patterns of waking. 00:14:23.943 --> 00:14:27.868 It's called sleep inertia. When we wake up out of the wrong state, 00:14:27.952 --> 00:14:30.260 I liken it to a washing machine cycle. 00:14:32.440 --> 00:14:35.034 cycle. And the first part is to add water, right? 00:14:35.118 --> 00:14:39.242 Then your clothes are soaking wet. You don't want to open the washing machine 00:14:39.325 --> 00:14:43.614 and try and function, put them on and wear them around while they're soaking wet 00:14:43.697 --> 00:14:47.985 and full of soap. So you have to wait until the cycle is through before you can, 00:14:48.069 --> 00:14:49.380 well, actually, let's... 00:14:49.690 --> 00:14:54.588 Put it in the dryer, too, before you want to wear them. So you can function. 00:14:54.672 --> 00:14:57.669 It just takes a little while for those clothes, 00:14:57.752 --> 00:15:01.340 that brain to dry out so you can actually function well. 00:15:01.423 --> 00:15:05.273 But it's better to wait through the whole cycle is complete. 00:15:05.356 --> 00:15:09.795 So that's why you want to set that 90-minute alarm clock. And, again, 00:15:09.879 --> 00:15:13.597 that's around 90 minutes because the first stage of sleep, 00:15:13.681 --> 00:15:18.990 the first cycle of sleep is actually a little longer, more like 105, 110 minutes. 00:15:19.690 --> 00:15:24.846 second ones, and third ones. They get sort of shorter and shorter as the night goes 00:15:24.929 --> 00:15:29.454 on. And in the last few cycles, you're just doing the N2 REM sleep cycle, 00:15:29.537 --> 00:15:33.178 which takes less time. And if you wake up out of REM sleep, 00:15:33.262 --> 00:15:38.102 there's usually no problem cognitively. Are you a fan of sleep trackers? Yeah. 00:15:38.185 --> 00:15:43.215 Do you use one? I have one on. I don't live my life by them because the best ones 00:15:43.298 --> 00:15:44.750 right now are about 70% 00:15:49.690 --> 00:15:52.553 okay, but take it with a grain of salt is what I'm saying. 00:15:52.636 --> 00:15:56.362 Tell us a little bit more about the washout that occurs in the brain during 00:15:56.446 --> 00:16:00.325 sleep and perhaps if there are any ways to ensure that it happens or to ensure 00:16:00.408 --> 00:16:03.728 that it doesn't happen. And obviously we want this to happen. Yeah. 00:16:03.811 --> 00:16:07.588 We talked about the circadian clock and how certain things happen at certain 00:16:07.672 --> 00:16:11.246 times. Well, one of the things that happens when we're awake and talking 00:16:11.329 --> 00:16:13.310 to each other is that there's a lot of, 00:16:14.280 --> 00:16:18.657 There's something that I'm learning from you today and you're learning from me. 00:16:18.740 --> 00:16:22.552 And that changes our synapses and it changes the way our proteins are 00:16:22.635 --> 00:16:26.455 processed. going to be folded and changed during sleep. 00:16:26.539 --> 00:16:30.167 This process actually uses a lot of ATP, the power 00:16:30.250 --> 00:16:35.081 structure the fuel of the brain. It unfolds also proteins while we're doing 00:16:35.165 --> 00:16:39.865 this, while we're using them. And so during that first part of the night, 00:16:39.948 --> 00:16:43.535 when we first fall asleep in the first 20 minutes or so, 00:16:43.618 --> 00:16:46.418 we're building that adenosine back into ATP. 00:16:46.501 --> 00:16:50.153 And that's probably why power naps are called power naps, 00:16:50.237 --> 00:16:53.037 because we're actually rebuilding the power. 00:16:53.120 --> 00:16:58.279 And then we're also cleaning out through the deep slow waves of slow-wave sleep. 00:16:58.362 --> 00:17:02.565 We're cleaning out all those misfolded proteins, unfolded proteins, 00:17:02.648 --> 00:17:05.887 and other things that get broken down and, you know, 00:17:05.971 --> 00:17:10.680 need to be rebuilt when we're asleep because of its use during wakefulness. 00:17:10.763 --> 00:17:15.025 So I liken that to, you know, having a big party during wakefulness, 00:17:15.109 --> 00:17:19.562 and you need all those party goers to leave in order to do the cleanup. 00:17:19.646 --> 00:17:22.010 What happens when a neuron is firing? 00:17:22.690 --> 00:17:25.670 is that it expands. The membrane expands a little bit. 00:17:25.754 --> 00:17:28.394 It becomes more translucent. That's how we know, 00:17:28.477 --> 00:17:31.741 one of the ways we know that neurons expand when they fire. 00:17:31.824 --> 00:17:35.939 And so every action potential, the membrane expands a little bit as sodium 00:17:36.023 --> 00:17:40.024 brings water into the cell. And then when they're silent, they contract. 00:17:40.108 --> 00:17:44.506 And so during slow waves, the cool thing is that the reason why you can measure 00:17:44.590 --> 00:17:48.081 them is that all the neurons at the same time, not all of them, 00:17:48.164 --> 00:17:50.490 but a good portion of them, are firing at 00:17:52.690 --> 00:17:57.572 So you think about that as contracting and expanding all at the same time. 00:17:57.655 --> 00:18:02.000 It's kind of like a bilge pump of the brain. So that can pump out. 00:18:02.083 --> 00:18:06.697 Glia are also really important for this in terms of cleaning up debris 00:18:06.780 --> 00:18:09.649 and transferring it to where it needs to go. 00:18:09.732 --> 00:18:12.497 So I think of it actually as a bilge pump. 00:18:12.580 --> 00:18:17.057 cleaning out our brain. Here you're talking about literally an expansion and 00:18:17.140 --> 00:18:22.157 a contraction of the neurons in unison and pushing the fluid through cleaning out any 00:18:22.240 --> 00:18:26.777 misfolded proteins or debris that might occur on the basis of these metabolic 00:18:26.860 --> 00:18:29.717 pathways. And the consequence of that is to what? 00:18:29.800 --> 00:18:33.977 To leave the brain in a state of more pristine action for the next day? 00:18:34.060 --> 00:18:37.337 Is that right? Yeah. You think of it again like a party. 00:18:37.420 --> 00:18:40.000 And if you don't clean up after that party, 00:18:42.580 --> 00:18:47.364 get more clogged. You know, people have a harder time moving around and enjoying 00:18:47.447 --> 00:18:50.893 themselves. And if that builds up day after day, you know, 00:18:50.976 --> 00:18:55.699 it's going to be cognition. That would be the party goers moving around becomes 00:18:55.782 --> 00:19:00.445 hard. And so this bilge pump that you describe is associated with the big slow 00:19:00.528 --> 00:19:05.494 waves of slow wave sleep. So this is going to occur more or less in the first third 00:19:05.578 --> 00:19:10.080 of the night. Is that right? That's right. And is this similar to the case 00:19:12.580 --> 00:19:16.817 later than you would normally, you miss the washout. You don't delay it. 00:19:16.900 --> 00:19:19.757 You miss the washout. That's right. That's right. 00:19:19.840 --> 00:19:22.817 So if you go to sleep at one or two in the morning, 00:19:22.900 --> 00:19:26.537 your sleep is still going to be dominated by N2 and REM sleep, 00:19:26.620 --> 00:19:28.000 not by slow wave sleep. 00:19:28.930 --> 00:19:33.516 You need to get that first bit of sleep. Would a caveat to that be if somebody 00:19:33.599 --> 00:19:37.587 normally goes to sleep at 1 or 2 a.m. and wakes up at 10 a.m.? Yeah. 00:19:37.670 --> 00:19:41.178 If that's their normal sleep cycle. Yeah. It should be okay. 00:19:41.262 --> 00:19:45.967 Somebody would want to do a sleep study with people who do that normally and see 00:19:46.051 --> 00:19:50.577 if also the melatonin releases later and the cortocosterone rise that happens 00:19:50.660 --> 00:19:55.150 normally in the morning also happens later. So if everything shifted, good. 00:19:58.930 --> 00:20:02.861 sleep. 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Again, that's eightsleep.com slash Huberman 00:21:11.419 --> 00:21:12.770 to save up to $350. 00:21:13.670 --> 00:21:18.072 I'd love for you to tell us about this incredible structure in the brain, 00:21:18.156 --> 00:21:22.619 which is the locus coeruleus, and hopefully tell us a little bit about its 00:21:22.703 --> 00:21:25.692 relationship to epinephrine, aka adrenaline. Yeah. 00:21:25.775 --> 00:21:30.546 So the locus coeruleus is filled with neurons that have in them norepinephrine, 00:21:30.629 --> 00:21:34.110 which is the brain's version of epinephrine or adrenaline. 00:21:34.193 --> 00:21:37.489 It's also called noradrenaline. And what it does is it, 00:21:37.573 --> 00:21:40.377 just like adrenaline in the rest of our bodies, 00:21:40.461 --> 00:21:43.410 it helps prime us to respond to our environment. 00:21:43.670 --> 00:21:46.992 So when locus ceruleus neurons fire and fire in a burst, 00:21:47.075 --> 00:21:51.553 we can switch our attention. And they will fire in a burst if, for example, 00:21:51.636 --> 00:21:55.809 a loud noise happens in the middle of your concentrating on something. 00:21:55.893 --> 00:22:00.431 It fires and it helps you switch your attention to that thing and then learn 00:22:00.514 --> 00:22:04.262 quickly from it. So it's really important in a stress response. 00:22:04.345 --> 00:22:08.883 It helps us do quick one-trial learning. But just tonic levels are signature 00:22:08.967 --> 00:22:10.730 of wakefulness and alertness. 00:22:11.000 --> 00:22:14.951 So too much is panic with the locus surrealist activity. 00:22:15.034 --> 00:22:20.425 A burst is switching attention. And then tonic levels are sustained constant 00:22:20.509 --> 00:22:25.900 attention. And then when we go to sleep, the locus surrealist slows and goes 00:22:25.984 --> 00:22:26.920 from about... 00:22:27.200 --> 00:22:32.686 on average um two hertz to about one hertz one cycle per second tonically and then 00:22:32.770 --> 00:22:38.480 when we go into REM sleep it's the only time when it shuts off completely and it 00:22:38.600 --> 00:22:43.540 appears that that complete silence is really really important for a number 00:22:43.623 --> 00:22:47.900 of things and the main thing that I think it's important for is 00:22:48.110 --> 00:22:52.767 the ability to erase and break down synapses that are no longer working 00:22:52.850 --> 00:22:56.038 for us. So they encode things that are false now, 00:22:56.121 --> 00:23:01.045 or they are encoding things that we learned in the novelty encoding pathway 00:23:01.128 --> 00:23:05.250 of our brain that have now been consolidated to other pathways. 00:23:05.334 --> 00:23:09.723 And so we need to now erase them from the novelty encoding pathway. 00:23:09.807 --> 00:23:12.210 And that is really, really important 00:23:18.110 --> 00:23:22.716 or that I don't know, what do you call those disks that you stick into computers? 00:23:22.799 --> 00:23:25.181 Thumb drives. You're acing your thumb drives. 00:23:25.265 --> 00:23:29.454 That thumb drive is what you carry around all day long. And then during sleep, 00:23:29.538 --> 00:23:33.673 you write that thumb drive to the cortex, to the long-term memory structures, 00:23:33.756 --> 00:23:38.165 and you need to refresh that thumb drive. And that's what happens during REM sleep 00:23:38.248 --> 00:23:41.945 when the locus surrealis is off. And so if we're not able to do that, 00:23:42.029 --> 00:23:45.780 we fill up that REM really quickly or that thumb drive really quickly, 00:23:45.863 --> 00:23:48.000 and we're not able to learn new things. 00:23:48.800 --> 00:23:54.368 that are years past, if you're never able to downscale that novelty encoding 00:23:54.452 --> 00:23:58.087 structure and purge it from that traumatic memory, 00:23:58.170 --> 00:24:02.260 it will stay fresh and new and then become maladaptive. 00:24:02.870 --> 00:24:08.184 What approaches are you aware of that can turn down the output of locus coeruleus 00:24:08.267 --> 00:24:13.381 during these phases of sleep and allow late stages of sleep each night to have 00:24:13.464 --> 00:24:18.645 their maximum positive effect? Is there anything that I can do besides avoiding 00:24:18.728 --> 00:24:21.843 serotonergic or neuroadrenergic compounds? Well, 00:24:21.926 --> 00:24:27.174 I would also avoid anything just prior to going to sleep that might excite those 00:24:27.257 --> 00:24:28.090 systems. 00:24:32.870 --> 00:24:33.657 And... 00:24:33.740 --> 00:24:38.622 enter sleep with as much calm as you can. So maybe deep breathing exercises. 00:24:38.705 --> 00:24:43.718 That's a beautiful way to calm your sympathetic fight or flight system is deep 00:24:43.801 --> 00:24:49.010 breathing. And if there's a way you can make your sympathetic nervous system calm 00:24:49.093 --> 00:24:53.845 down before you go to sleep, might be for you meditation or deep breathing 00:24:53.928 --> 00:24:58.240 exercises. It might be for some, a warm bath or a comforting book, 00:25:03.740 --> 00:25:07.085 which makes you feel happy and calm is what you should do. 00:25:07.168 --> 00:25:10.867 And if you instead go to sleep while you're anxious or hyped up, 00:25:10.950 --> 00:25:15.832 then your sleep could become maladaptive. I'd love for you to share with us a little 00:25:15.915 --> 00:25:19.260 bit more about the spindles that have come up a few times. 00:25:19.343 --> 00:25:23.574 The density of our sleep spindles, the number that we produce per minute, 00:25:23.657 --> 00:25:27.120 is well correlated with our intelligence in the first place. 00:25:27.204 --> 00:25:31.967 And that no matter what your intelligence is and no matter what your sleep spindle 00:25:32.050 --> 00:25:32.883 density is, 00:25:33.740 --> 00:25:37.218 something during the day and increase your sleep spindle density, 00:25:37.302 --> 00:25:41.109 it's really almost perfectly correlated with our ability to consolidate 00:25:41.192 --> 00:25:45.219 that information and incorporate it into the schema that we already have in 00:25:45.302 --> 00:25:47.904 our brain. So if you try and learn something new, 00:25:47.987 --> 00:25:50.972 even if your sleep spindle density at baseline is great, 00:25:51.056 --> 00:25:55.017 if you don't increase your sleep spindles that night, you're not going to 00:25:55.100 --> 00:25:57.960 you know, use sleep to really incorporate it. 00:25:58.043 --> 00:26:03.192 One of the things we now know through some great studies by Julie Seep and Anita 00:26:03.276 --> 00:26:07.902 Luthi is that sleep spindles are accompanied by an incredible plasticity 00:26:07.985 --> 00:26:13.003 out in the distal dendrites, the listening branches of our neurons that listen 00:26:13.087 --> 00:26:17.647 to other cortical areas. So there are proximal dendrites in our neurons 00:26:17.731 --> 00:26:22.422 that listen to the external world and are conducted through the thalamus. 00:26:22.505 --> 00:26:24.860 And then there are distal dendrites, 00:26:25.100 --> 00:26:29.625 listen to an internal kind of, you know, conversation that's happening in 00:26:29.709 --> 00:26:33.602 our brains. It's kind of, you know, our internal state, really. 00:26:33.686 --> 00:26:38.527 And during sleep spindles, that's when those distal dendrites are able to best 00:26:38.610 --> 00:26:42.125 learn from other cortical areas and from the hippocampus. 00:26:42.208 --> 00:26:46.671 It is during sleep spindles that the hippocampus and the cortex are best 00:26:46.754 --> 00:26:50.269 connected and when that incredible plasticity can happen. 00:26:50.352 --> 00:26:52.120 So when I talk about schema, 00:26:55.100 --> 00:27:00.848 of calcium into those distal dendrites and where plasticity happens in just huge 00:27:00.932 --> 00:27:05.352 amounts. During that sleep- spindle stage of sleep, which is N2 stage. 00:27:05.436 --> 00:27:09.556 There's another excitatory event that comes all the way from the brainstem 00:27:09.639 --> 00:27:13.248 and projects everywhere in our cortex, which is called PGO waves, 00:27:13.331 --> 00:27:17.565 which we should generalize to P waves because they come from the pons and go 00:27:17.648 --> 00:27:21.200 to the thalamus and then the cortex happens all over the brains. 00:27:21.283 --> 00:27:25.430 And that is where glutamate, which is a major excitatory neurotransmitter 00:27:25.610 --> 00:27:29.995 involved in learning and plasticity is being released in big amounts also 00:27:30.078 --> 00:27:35.137 in those distal dendrites. So P waves and spindles work together to cause plasticity 00:27:35.220 --> 00:27:40.217 and sew our schema together, which could be the origins for insight and creativity. 00:27:40.301 --> 00:27:44.869 Now, when P waves were first discovered, it was thought to be random because 00:27:44.953 --> 00:27:49.460 this small area that generates P waves all over the brain projects all over 00:27:49.543 --> 00:27:54.207 the thalamus and causes P waves all over. And you don't Measure P waves 00:27:54.290 --> 00:27:57.081 all over the brain at the same time. In fact, 00:27:57.164 --> 00:28:02.317 it just seems sporadic and random. And P waves are also happening even more during 00:28:02.401 --> 00:28:07.363 REM sleep, rapid eye movement sleep. So that's why people think that REM dreams 00:28:07.446 --> 00:28:11.150 are so random is because these P waves are random and they 00:28:11.270 --> 00:28:16.167 could generate dreams because they're an internal source of excitation that kind 00:28:16.250 --> 00:28:20.836 of replaces the outside world during our dream state. And so these P waves, 00:28:20.919 --> 00:28:25.131 if they are random, could be the underlying reason why creativity can 00:28:25.214 --> 00:28:28.243 happen there is because we're randomly activating, 00:28:28.327 --> 00:28:32.850 co-activating different things in our brain that we can then sew together. 00:28:32.933 --> 00:28:37.083 But it might not be as random as we think. So that's a caveat there. 00:28:37.166 --> 00:28:40.030 I'd like to take a quick break and acknowledge 00:28:41.270 --> 00:28:44.861 AG1. 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So that's with a numeral two back numeral two 00:29:52.162 --> 00:29:55.370 routine. Just go to drinkag1.com slash Huberman. 00:29:55.950 --> 00:29:59.917 - So locus coeruleus is suppressed, so we can't release norepinephrine. 00:30:00.000 --> 00:30:06.105 and act out our dreams, this almost starts to sound like a little bit of a built-in, 00:30:06.188 --> 00:30:09.199 while sleeping, trauma therapy. So please, 00:30:09.282 --> 00:30:14.660 if there's anything about locus coeruleus and dreams that can help people 00:30:14.970 --> 00:30:18.612 basically extinguish traumas or traumatic features to real life events. 00:30:18.695 --> 00:30:22.630 We definitely want to know about them. Yeah, yeah. Well, I think one of the 00:30:22.800 --> 00:30:25.872 things that people thought might help after a trauma, 00:30:25.955 --> 00:30:28.551 like a school shooting or whatever, you know, 00:30:28.634 --> 00:30:31.766 car accident is to talk about it. And in, but in fact, 00:30:31.849 --> 00:30:36.291 that ended up being counterproductive. And I think one of the reasons why it 00:30:36.374 --> 00:30:40.041 was counterproductive is because it didn't take them back down. 00:30:40.125 --> 00:30:43.971 It brought them up and continued to reactivate the emotions of it, 00:30:44.054 --> 00:30:48.495 but then didn't emphasize the safety effect that it's over or help them work 00:30:48.579 --> 00:30:50.960 through how they might avoid it again in 00:30:52.800 --> 00:30:56.873 the sympathetic nervous system down again before they went to sleep. 00:30:56.956 --> 00:31:01.029 And none of these studies has sleep ever been considered. But to me, 00:31:01.112 --> 00:31:02.640 that's the key part is... 00:31:02.790 --> 00:31:07.314 bringing down your sympathetic nervous system before you go to sleep so that 00:31:07.398 --> 00:31:12.104 your sleep can be adaptive, your locus rilus can shut off like it normally does 00:31:12.187 --> 00:31:15.438 or should do, and then able to erase the novelty of it. 00:31:15.522 --> 00:31:20.288 The other thing that I just mentioned a minute ago was that the emotional system 00:31:20.372 --> 00:31:23.987 is highly activated in REM sleep, and that's definitely true. 00:31:24.070 --> 00:31:27.950 And that might seem counterproductive in terms of the nightmares 00:31:32.790 --> 00:31:36.695 rather than reinforcing the emotionality of the trauma. 00:31:36.779 --> 00:31:41.699 And I think the key to that, again, is the absence of norepinephrine. 00:31:41.782 --> 00:31:47.211 So even though the emotional system is in high gear, without norepinephrine, 00:31:47.294 --> 00:31:52.650 you can actually divorce those highly activated emotions from the cognitive 00:31:52.733 --> 00:31:58.524 parts of the memory that you have just written out in that N2 stage of sleep when 00:31:58.607 --> 00:32:00.710 the sleep spindles are going. 00:32:02.790 --> 00:32:07.386 the information that you'll need to survive and to make that adaptive. 00:32:07.469 --> 00:32:10.410 And now you need to divorce from that person 00:32:10.500 --> 00:32:14.924 schema and from that semantic parts of memory, the emotional part. 00:32:15.008 --> 00:32:19.717 Because whenever you remember something, it's fine if you remember... 00:32:19.800 --> 00:32:23.827 being emotional at the time, but you don't want to bring back and so into 00:32:23.910 --> 00:32:28.162 that memory, all of the same emotional systems. You don't want to bring back, 00:32:28.245 --> 00:32:31.878 you know, the heart rate changes and the sweating and all of that. 00:32:31.961 --> 00:32:36.270 You want to be able to remember all the parts of it and even remember that you 00:32:36.353 --> 00:32:40.211 were traumatized and that you did cry and that you did have, you know, 00:32:40.294 --> 00:32:44.040 your heart was racing. But when you're talking about it years later, 00:32:44.123 --> 00:32:45.080 you don't want to 00:32:49.800 --> 00:32:53.778 memory because you're basically putting yourself through the same trauma which 00:32:53.861 --> 00:32:57.787 is what people with PTSD have they don't want to recall this traumatic memory 00:32:57.870 --> 00:33:02.004 because it's reliving it it's like it's just happening again so that's what we're 00:33:02.087 --> 00:33:02.857 thinking is that 00:33:02.940 --> 00:33:08.317 the emotional parts are not able to be divorced because the norepinephrine system 00:33:08.401 --> 00:33:10.760 is not downscaled during REM sleep. 00:33:11.820 --> 00:33:17.466 that REM sleep serves to instead reinforce and in fact amplify the emotions because 00:33:17.550 --> 00:33:21.125 your emotional system is up, locus surrealis is high, 00:33:21.208 --> 00:33:26.578 re-sewing in every night the emotionality of those memories and with the memory 00:33:26.662 --> 00:33:31.894 itself. I must say you've taught us a tremendous amount in a relatively short 00:33:31.977 --> 00:33:36.740 amount of time about the architecture of sleep, the different phases, 00:33:41.820 --> 00:33:45.657 want to say thank you for taking the time to sit down and have this conversation 00:33:45.741 --> 00:33:47.863 that so many people are sure to benefit from. 00:33:47.946 --> 00:33:51.796 I know I speak for everybody when I say thank you so much. Thank you so much.