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Welcome to Huberman Lab Essentials. This program revisits past episodes and introduces the most effective and practical science-based tools for mental health, physical health, and performance improvement. I am Andrew Huberman, Now, let's begin the conversation with Dr. Gina Poe Hello, Dr. Gina Po. thank you. I was really looking forward to this conversation. I think many people will be interested in your research related to sleep, problem-solving skills, creativity, and many other important topics. First, could you briefly explain sleep, something familiar to all of us but rarely understood properly? I would appreciate it if you could explain the various stages of sleep, the differences between each stage,
and what ideal sleep might look like Therefore, sleep is completely different from the waking state, and in fact, it cannot be replaced by any waking state we have created so far. The chemical composition of our brain is completely different, and sleep is broadly divided into two stages: non-REM sleep and REM sleep, and these two stages are completely different from each other. There are three stages even within non-REM sleep. Stage 1 is the stage that appears when you start to fall asleep; it is a state of overwhelming drowsiness, and an interesting rhythm appears in the brain, namely fast gamma waves. Stage 2 is a very interesting state, but in the past, sleep researchers
overlooked it, considering it a transitional state between the waking state and Stage 3 slow-wave sleep, which shows the most impressive changes. Stage 3 slow-wave sleep is a stage in which large, slow waves flow throughout the brain, and it has been revealed that it plays a role in purifying the brain. Well, one of those long, slow waves plays a really important role in clearing the brain and restoring our body, which has been awake all day. And REM sleep is the best known because it is when the most active dreams occur. People who wake up from REM sleep almost always say they had a very strange dream. This is REM sleep, or rapid eye movement sleep. Thus, human sleep is divided into four stages, and these four stages cycle and
restart approximately every 90 minutes. If you get perfect sleep, you go through these stages about 4 to 5 times a night 7 hours and 30 minutes to 8 hours Then, what about light sleep? yes. When you fall into a light sleep, you may think about movements in your dreams or wake up suddenly. This kind of thing happens often early in the night, doesn't it? yes. Yes, this is the first stage of sleep, namely stages 1 and 2. Stage 2 sleep is really interesting because sleep spindles and the K complex appear. Sleep spindles are microscopic activities with a frequency of 10 to 15 Hz. This can be described as an interaction between the thalamus and the cerebral cortex. The thalamus is the gateway to consciousness, and the neocortex
often report that they had a hallucinatory dream. Although it is not as long as a dream during REM sleep, you will experience a hallucinatory state. Would these sleep patterns be significantly different from the sleep and dream patterns that appear late at night or in the morning. In fact, if you learned something new or had a new sensorimotor experience on that day , that experience is reflected much more in the dreams during the early part of sleep than in the dreams during the later part dispersedly integrated into the cerebral cortex from early structures such as the hippocampus deep within the temporal lobe
, it appears that the memory moves from the hippocampus to the cerebral cortex, and dreams containing that memory also appear in the latter part of the night. Siddhartha Ribeiro conducted an excellent study on day-sleeping mice to investigate the process of discovered that whenever the REM sleep stage is repeated, memories move from the hippocampus to the first, second, and third areas, which are projected from the hippocampus to the hippocampus. In other words, you Melatonin is known as a hormone that is secreted at night and induces drowsiness. Then, when is growth hormone secreted during sleep Growth hormone is secreted throughout the day and night, but
deep slow-wave sleep experienced during the first sleep cycle is the time when growth hormone is secreted in large quantities in both men and women. If you miss this first deep slow-wave sleep, you will also miss this period when growth hormone is secreted in large quantities say that secreting a large amount at once and secreting it little by little have different effects. Protein synthesis also takes place actively. For example, the synthesis of proteins that form memories in the brain How could you miss the first 90 minutes? It is none other than yourself. For example, I usually go to bed at 10 PM. And from 10:00 AM to 11:30 AM is the first stage of sleep, during which growth hormone is secreted in large quantities. In that case, if I
go to bed at 11:30 or midnight, will I miss this first stage of sleep? Does simply going to bed late mean you can't properly experience the first stage of sleep Every cell in our body has a biological clock, and these biological clocks are synchronized with each other so that the cells are ready to respond to growth hormone secreted at specific times. If we miss this time, furthermore, this time is also related to the melatonin secretion time. Therefore, if you miss this time, growth hormone may still be secreted, but your body's biological clock will have already moved on to the next stage. Ultimately, it is the working of the biological clock. So, does that mean we need to
maintain a consistent bedtime and wake-up time In fact, one of the best indicators of good nerve health as you age is regular sleep duration. Then, what are the other factors that inhibit growth hormone secretion or other components of the first stage of sleep ? For example, can consuming caffeine or alcohol the night before reduce the efficiency of the first stage of sleep, even if you go to bed at the same time? That is certainly the case with alcohol. Alcohol is a REM sleep depressant and inhibits the transition process to REM sleep, the second stage of sleep where sleep spindles appear. We haven't talked about the function of sleep spindles yet, but they are very important for
transferring memories to the cerebral cortex. This is a special period when the hippocampus, which acts like the brain's RAM, stores memories on a hard disk called the cerebral cortex. This period is a what about the second and third 90-minute sleeps? Is there anything that makes this time slot special? Besides the fact that it lasts until late at night, what other features does it have As the night gets later, the duration of REM sleep gradually increases. Changes also occur in hormones; growth hormone and melatonin levels begin to decrease, but other hormone levels increase. Therefore, this stage is a very important sleep stage and should not be neglected. According to several studies,
creativity is most actively displayed during this sleep stage and new experiences are integrated in dreams in a new way, and the brain's schemas are built. It's just like a computer called the brain opening folders, comparing documents, and finding commonalities. These two documents look very similar, but there are slight differences. And that difference can be conceptually connected. Perhaps one of the sources of creativity is finding related things. You might be able to find things that are slightly connected and strengthen those links to make your way of thinking interesting and original Many people, including myself, wake up once or twice in the middle of the night to go to the bathroom. I also tried
reducing my water intake before going to bed. I heard that the urge to urinate is. So, I changed my habit to drinking the last beverage of the day slowly, and it seems to be helping. Is waking up in the middle of the night harmful to my health ? Or should we view it as a normal phenomenon observed in the sleep structure of some people Actually, I don't think there is any need to worry. Since sleep is surprisingly well regulated by homeostasis, you do not need to worry about how much you sleep unless you intentionally sleep. This is especially true when you are cutting back on sleep while doing very rewarding and interesting work. This is because even such behavior stresses the body and
deprives it of various important elements we are talking about. It is perfectly normal to wake up at least once in the middle of the night to go to the bathroom If you can fall back asleep within a reasonable amount of time, or even if it takes about an hour, do not worry. Having lifestyle habits that allow you to make up for insufficient sleep the next morning or at night, or going to bed a little earlier, are also good methods. Yes, REM sleep time lengthens in the latter part of the night, and this is considered the deepest sleep. Of course, slow-wave water is also considered deep water. It's deep sleep.
Yes, slow-wave sleep is called deep sleep and REM sleep is called rapid eye movement sleep, but are you saying that REM sleep is actually deeper sleep The reason slow-wave sleep is called deep sleep is that it is difficult to wake up from that state . And even if you wake them up, most of them are confused and want to go back to sleep, and in fact, they can easily fall back asleep. When woken from REM sleep, it is common for people to report having an experience very similar to being awake. It is a very vivid memory. One of the reasons REM sleep is deeper may be that deep slow-wave sleep disappears, especially in adults or the elderly So, the size of the western wave becomes smaller. It could be that the size of the waves is decreasing, but it is
not certain. That is why REM sleep is the deepest stage of sleep. The body becomes paralyzed during REM sleep, right Yes, usually the body becomes paralyzed, so that is really a relief. Because that is a time when we are dreaming within stories, we might end up harming ourselves. In fact, we sleepwalking occurring during the slow-wave sleep stage is a state where sleep and wakefulness are mixed. You predict at all what they will do. Although it cannot be consciously controlled, it can move safely even in a sleepwalking state and can even During REM sleep, one is unaware of the external world and acts out dreams. For example, they might do
Otherwise, you may act on your dream and Therefore, as morning or your usual wake-up time approaches, it is said to be important to wake up after completely finishing a 90-minute sleep cycle if possible wake up in a dazed state This is called sleep inertia , and it can be metaphorically explained as waking up from an incorrect sleep state. The 90- minute cycle is the same as the washing process of a washing machine. The first step is to add water. Then your clothes will get soaked. You wouldn't want to walk around in wet clothes as soon as you open the washing machine, would you? You probably would n't want to dry your clothes with them covered in soap suds I have to wait until the washing is finished-no,
even put it in the dryer-before I can wear it properly for daily life. It might. That is why it is a good idea to set a 90-minute alarm. The reason it is 90 minutes is that the first stage of sleep, or the first sleep cycle, is actually a bit longer, around 105 to 110 minutes, but the second and third cycles get progressively shorter as the night deepens. The last few cycles are N2 REM sleep cycles, so they are shorter. Even if you wake up from REM sleep, there are . 70% is okay, but I'm saying you shouldn't blindly trust it And is there a way to make that phenomenon occur, or conversely, to prevent it from happening? Of course, we hope this phenomenon happens. yes
. We talked about the biological clock and things that happen at specific times. When we are awake and converse with each other, plasticity develops in the brain. There is something I am learning from you today, and something you are also learning from me, which changes our synapses and This process actually uses a lot of ATP, which is the brain's energy source and fuel Proteins are also unraveled during this process. So, when you first fall asleep at night, the first 20 minutes or so the reason naps are called 'power naps' is precisely because of this energy recharging. And during the deep slow-wave sleep stage, misfolded proteins, unfolded proteins, and other substances that were used and broken down while awake are
removed, and a process of reconstructing them during sleep is all the partygoers leave to clean up. expands. The cell membrane expands slightly and becomes more transparent . One way to know that the cell membrane expands when a neuron is activated is precisely this expansion. In other words, every time an action potential occurs, sodium ions draw water into the cell, causing the cell membrane to expand slightly. And when there is no activity, the cell membrane contracts. The reason slow waves can be measured is that all neurons are activated simultaneously and inactive at the same time. Of course, not all neurons are like that, but
a significant number of neurons are simultaneously activated and inactive. It is as if the cell membrane contracts and contracts like the bilge pump in the brain. Glial cells also play an important role in this process, removing waste products and transporting them to where they are needed So I think this is the brain's bilge pump cleaning it. The neurons expand and contract simultaneously. And it pushes out bodily fluids. yes based on these metabolic pathways. yes What will the result be? It Yes, think about the party again. If you try to host another party the next day without cleaning up after the first one, it will just get even more congested. People end up having difficulty moving and enjoying themselves. And if
this phenomenon accumulates every day, it will lead to problems with cognitive function. It's like the partygoers are finding it difficult to move So, the 'bilge pump' you mentioned is related to large, slow waves on the surface of the water. This phenomenon occurs during the first third of the night. yes. Is that right? yes. Is. The important thing is not delaying sleep, but missing the final stage of sleep is the problem. you're right. If you go to bed at 1 or 2 AM, N2 layer and REM sleep will predominate, and slow-wave sleep will be insufficient. Therefore, you must sleep for at least the first few hours confirm whether melatonin secretion or the rise in cortisol levels that normally appears in the morning is also delayed. If everything
has changed, it is a good sign. Now, I would. Well, the blue nucleus has many neurons containing norepinephrine, which plays the same role as epinephrine or adrenaline in the brain. It is also called norepinephrine. Like adrenaline in other parts of our body norepinephrine helps us prepare to react to the surrounding environment. When blue nucleus neurons are momentarily activated, attention can be switched. For example, if a loud noise occurs while you are concentrating on something, blue nucleus neurons are activated, diverting your attention to the noise and enabling you to learn quickly. Therefore, it plays a very important role in the stress response. It certain level, it indicates a state of arousal, that is, alertness
. If blue nuclear activity is excessive, it is a state of panic. Momentary activation refers to a shift in attention, while a certain level refers to a state of maintaining continuous attention. And when we fall asleep, the activity of the blue nucleus slows down, decreasing, meaning it continues to be active at one cycle per second And when you enter REM sleep, the activity of the blue nucleus completely stops. This complete standstill I think the most important thing is the ability to erase and break down synapses that are no longer helpful to us integrated into other pathways disk plugged into a computer, or, ah, a USB drive. Let me use the analogy of erasing a USB memory stick
. You carry a USB memory stick around all day, and while you sleep, the information stored on that memory is saved in the long-term memory structure of the cerebral cortex. And this memory needs to be updated, and that process takes place during REM sleep as the blue nucleus stops its activity. If this update is not performed properly, the brain's RAM or USB memory will fill up too quickly, making it impossible to learn new things. Even memories from a few years ago, if you cannot reduce the structure encoding new information in those memories and completely remove them from traumatic memories, those memories continue to feel new and eventually lead to maladaptive results.
other way besides avoiding substances that stimulate serotonin or norepinephrine Of course, you should avoid anything that can stimulate this system right before falling asleep. Since there are many stimulating and stress-inducing video games these days, it is important to go to bed with the calmest mind possible Deep breathing exercises are also a good method. Deep breathing is effective in calming the sympathetic nervous system's fight-or-flight response meditation, deep breathing, a warm bath, or reading a relaxing book. I like activities that are neither too stimulating nor too boring, and give a happy and calm feeling
Going to bed in an anxious or agitated state can reduce the quality of sleep. Could you also explain sleep room flirtations in a bit more detail? It is said that the density of sleep spindles, that is, the number of spindles generated per minute, is closely related to intelligence. Regardless of intelligence level or sleep spindle density, learning something during the day and increasing sleep spindle density is almost perfectly correlated with the ability to integrate that information and incorporate it into schemas already existing in the brain. Therefore, even if your sleep divergence density is usually high, when you try to learn something new, if you
One of the facts revealed through the excellent research of Julie Jive and Anita Rutti is that sleep spindles are related to the remarkable plasticity of the distal dendrites of neurons, that is, the branches that receive signals from other cortical regions seems like it represents our inner state. While sleep spines appear, terminal dendrites become best able to learn from other cortical regions and the hippocampus During sleep spindles, the hippocampus and cortex are best connected, and remarkable plasticity can occur. The schema I am referring to is the interaction between the cortex. As a large amount of calcium flows into the terminal dendrites, a tremendous amount of plasticity occurs. In the sleep spindle stage, or N2 stage,
PGO waves are generated, which are another excitatory signal originating in the brainstem and transmitted throughout the cortex. This can be generalized as the P wave because it originates in the pons, passes through the thalamus, and is transmitted to the cortex. This secreted in large quantities from terminal dendrites. Therefore, P waves and spindle waves work together to induce neuroplasticity, and schemas also work together to become a source of insight and creativity. When P waves were first discovered, they were considered to be random. This is because a small area in the entire brain that generates P waves
affects the entire thalamus, causing P waves to be generated throughout the brain In reality, it is not possible to measure P waves simultaneously throughout the entire brain. It just appears to appear sporadically and randomly . P waves occur more actively during REM sleep (rapid eye movement sleep). The reason people think that dreams during REM sleep are random is precisely because of the randomness of these P waves, and because P waves act as an internal source of excitement that replaces the external world while dreaming. So, if this P wave is random, the fundamental reason why creativity is manifested might be that we can randomly or simultaneously activate various parts of the brain and combine them
However, it might not be as random as you think. You must keep that in mind. If the blue nucleus is suppressed, norepinephrine is not secreted, so dreams cannot be acted out. This may sound like a kind of internal trauma therapy that takes place during sleep. So, regarding the blue core and dreams, and whatever that may be to help people eliminate trauma or traumatic characteristics experienced in real-life events, we certainly want to know. Yes, one of the things I thought would be helpful after a trauma like a school shooting or a traffic accident was talking about it, but in reality, it backfired. And I think
one of the reasons it backfired is that it failed to calm the emotions Rather, it heightened emotions and continued to reactivate the feelings of that time, but it did not instill a sense of relief that the matter was over or help to think of ways to avoid such a situation again in the future. There was also no way to calm the sympathetic nervous system before falling asleep. However, sleep was not considered at all in all these studies However, I think the key is to allows the blue core to stop functioning normally or the functions that need to function, and erase the new sensation of that work Another point I just mentioned is that the emotional system becomes very active during REM sleep This is clearly true, and
in nightmarish situations, it may actually seem to have a counterproductive effect. How can REM sleep be helped to play a therapeutic role instead of reinforcing the emotional aspects of trauma? I think the key lies in the absence of norepinephrine . Even if the emotional system is actively activated, in the absence of norepinephrine, the activated emotion can be separated from the cognitive memory part just recorded during the N2 phase where sleep spindles appear. Since the information necessary for survival and adaptation has already been organized, we must now separate the emotional part from the schema and semantic memory part. It is okay to feel the emotions of that time when remembering something
, but there is no need to recall the entire emotional system of the past and weave it into the memory. You don't want to recall feelings like changes in your heart rate or sweating again, do you? You, you won't want to go through all of that again Otherwise, who would want to recall traumatic memories? Because it amounts to going through the same trauma again. That is exactly what people suffering from PTSD feel. The reason I don't want to recall traumatic memories is that it feels like going through the experience again. It's as if that thing is happening again. So, we plays a role in strengthening and amplifying emotions. This is because the emotional system and the blue
nucleus are activated, reconnecting the emotional aspects of that memory with the memory itself every night Thank you for providing so much information, such as sleep structure and various sleep stages, in such a short amount of time. In particular, I was able to obtain a lot of practical information. I sincerely thank you for sharing a conversation that will be helpful to so many people. On behalf of everyone, I would like to thank you once again. thank you so much.
