Essentials: Use Sleep to Enhance Learning, Memory & Emotional State | Dr. Gina Poe

Huberman Lab

In this Huberman Lab Essentials episode, Dr. Gina Poe, a professor of integrative biology and physiology at UCLA, explores the science of sleep architecture and its critical role in memory consolidation,

Key takeaways

• The first 90 minutes of sleep, particularly deep slow-wave sleep, are crucial for releasing a large bolus of growth hormone essential for brain repair and memory consolidation.
• Sleep spindles in stage 2 sleep help transfer memories from the hippocampus to the cortex, supporting long-term learning.

Main topics

• Sleep architecture: stages 1–3 (non-REM) and REM
• Memory consolidation during early vs. late sleep

Notable quotes

"If you miss that first deep slow wave sleep period, you also miss that big bolus of growth hormone release."

Conclusion

Sleep is not merely rest but an active, essential process for brain health, memory formation, emotional

Transcript preview

Speaker 1 (0:00) Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. And now for my discussion with Dr. Gina Poe. Dr. Gina Poe, welcome. Thank you. I've really been looking forward to this conversation. I know that many people are going to be excited to learn about your work as it relates to sleep, as it relates to problem solving, creativity, and a number of other important topics. Speaker 1 (0:34) To start things off, I would love for you to educate us a bit about this thing that we are all familiar with and yet very few of us understand, which is sleep. Could you describe the various phases of sleep that exist, what distinguish them, and perhaps frame this within the context of what would a perfect night's sleep look like? All right. So sleep is really different from wakefulness and, in fact, can't be replaced. Speaker 1 (0:58) by any state of wakefulness that we've been able to come up with so far. Our brain chemistry is completely different. And in the different stages of sleep, which there is non-REM and REM are the two major states of sleep. Those two states are entirely different from one another too. And even within non-REM, there are three states. Stage one, which is what you slip into when you first falling asleep, it's dozing. There's kind of an interesting rhythm that goes on in the brain. It's kind of a fast gamma rhythm. And then there's stage two, which which is a really cool state. Speaker 1 (1:30) used to ignore sleep researchers because it was a transient state between wakefulness and the deep stage three slow wave sleep, which is the most impressively different, which is when big slow waves sweep through our brain. And now we realize that it cleans our brain. One of the things that those big slow waves do is cleans our brain and does other really important things to restore us from a day of wakefulness. And then REM sleep, which is the most popular because that's where we have the most active dreams. When you wake up someone out of REM. Speaker 1 (1:59) sleep, they'll almost always report having dreamed something really bizarre. That's called REM sleep, rapid eye movement sleep. So those are the four states of sleep, of human sleep. And we cycle through them every 90 minutes or so. And then we start over again. And we have about five of those per night for a perfect night's sleep, four or five, something like that. So a perfect night's sleep is seven and a half, eight hours. And what about the sleep where we are lightly asleep and we might have a dream that has us somehow thinking about movement or that we jolt ourselves awake. That often happens early in the night. Yeah. Yeah. That's the first stage, stage one and stage two of sleep. And stage two sleep is really cool because that has something called sleep spindles and K complexes. And what sleep spindles are, are a little of activity that's 10 to 15 Hertz. Speaker 1 (2:51) in frequency. It's a conversation between the thalamus and the cortex. The thalamus is the gateway to consciousness and the neocortex, you know, processes all our cognition. And if you wake up out of that state, you will often report a dream, like a hallucination style dream. It won't be a long dream report like you have out of REM sleep, but it will be some hallucination state. Are they quite different than the patterns of sleep and dreaming that occur later in the night or toward morning? There is some evidence that the first four hours of sleep are very important for memory processing. And in fact, if you've learned something new that day or have experienced a new sensory motor experience, then your early sleep Speaker 1 (3:38) dreams will incorporate that experience much more than the later sleep dreams. Later as that memory gets consolidated from the early structures, which are the hippocampus deep in the temporal lobe to the cortex in a distributed fashion, that memory seems to move from that hippocampus to the cortex and also the dreams that incorporate that memory also move later in the night. So there was a great study by Siddhartha Ribeiro, who studied the consolidation of memories from the hippocampus to the cortex in a rat across the period of a full day's sleep, because rats sleep in the daytime. And he found that each subsequent REM sleep period moved that memory from the hippocampus to the first... Speaker 1 (4:25) first area that projects to it and then the second area and then the third area. And you can see the memory moving throughout the sleep. There's a number of different hormones associated with the different stages of sleep. We know that melatonin is a hormone of nighttime that makes us sleepy. What about growth hormone release? When does that occur during sleep? So growth hormone release happens all day long and all night long. But the deep, slow-wave sleep that you get the very first Speaker 1 (4:54) sleep cycle is when you get a big bolus of growth hormone release and in men and women equally. And if you miss that first deep slow wave sleep period, you also miss that big bolus of growth hormone release. And you might get ultimately across the day just as much overall growth hormone release. But endocrinologists will tell you that big boluses do different things than a little bit eked out over time. There's also a big push to synthesize proteins. So that's when the protein synthesis part that builds memories, for example, in our brain happens in that first cycle of sleep. So you don't want to miss that, especially if you've learned something really big and needs more synaptic space to encode it. How would somebody miss that first 90 minutes? Sleep depriving themselves. Yeah. So let's say I normally go to sleep at... Speaker 1 (5:47) 10 p.m. And then from 10 to 11.30 would be this first phase of sleep. And that's when the growth hormone, big bolus of growth hormone would be released. Does that mean that if I go to sleep instead at 11.30 or midnight that I missed that first phase of sleep? Yeah. Why is it not the case that I get that first phase of sleep just simply starting later? Every cell in our body has a clock and all those circadian clocks are synchronized. And so our cells are ready to Speaker 1 (6:14) respond to that growth hormone release at a particular time. And if we miss it, and it's a time in relation to melatonin also. So if you miss it, yeah, you might get some growth hormone release, but it's occurring at a time when your clock has already moved to the next phase. And so it's just a clock thing. So what this means is that we should have fairly consistent bedtimes in addition to fairly consistent wake times. Is that right? Exactly. And in fact, one of the best markers of good neurological health when we get older is consistent bedtimes. I'd like to take a quick break and acknowledge one of our sponsors, Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the electrolytes, sodium, magnesium, and potassium in the correct amounts, but no sugar. Speaker 1 (7:00) Proper hydration is critical for optimal brain and body function. Even a slight degree of dehydration can diminish cognitive and physical performance. It's also important that you get adequate electrolytes. The electrolytes, sodium, magnesium, and potassium, are vital for functioning of all the cells in your body, especially your neurons or your nerve cells. Drinking Element Dissolved in water makes it very easy to ensure that you're getting adequate hydration and adequate electrolytes. To make sure that I'm getting proper amounts of hydration and electrolytes, I dissolve one packet of Element Speaker 1 (7:29) in about 16 to 32 ounces of water when I first wake up in the morning, and I drink that basically first thing in the morning. I'll also drink Element dissolved in water during any kind of physical exercise that I'm doing, especially on hot days when I'm sweating a lot and losing water and electrolytes. Element has a bunch of great tasting flavors. I love the raspberry. I love the citrus flavor. Right now, Element has a limited edition lemonade flavor that is absolutely delicious. I hate to say that I love one more than all the others, but this lemonade flavor is right up there with my favorite other one, which is raspberry or watermelon. Again, I can't pick just one flavor. I love them all. If you'd like to try Element, you can go to drinkelement.com slash Huberman, spelled drinkelement.com slash Huberman, to claim a free Element sample pack with a purchase of Speaker 1 (8:19) What other things inhibit growth hormone release or other components of this first stage of sleep? Are there things that I perhaps do in