Huberman Lab
GUEST SERIES | Dr. Matt Walker: Improve Sleep to Boost Mood & Emotional Regulation
01 May 2024
Chapter 1: What is the connection between sleep and mental health?
Welcome to the Huberman Lab guest series, where I and an expert guest 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. Today marks the fifth episode in our six-episode series all about sleep with expert guest Dr. Matthew Walker.
Today's episode focuses on the inextricable link between sleep and our mental health. For instance, a specific stage of sleep called rapid eye movement, or REM sleep, is critical for removing the emotional content of our previous day's memories, and in doing so, provides a sort of therapy within sleep that allows us to feel emotionally restored when we wake the next morning.
Chapter 2: How does REM sleep affect emotional processing?
We discuss what happens when you are deprived of REM sleep to a small or greater degree, and we discuss how to improve the quality and quantity of your REM sleep in order to ensure mental health. We also discuss science-based protocols for reducing rumination and negative thoughts before sleep.
The information shared by Dr. Walker in today's episode is sure to be critical for anyone that is either struggling with mental health issues or who simply wants to bolster their overall mental health. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford.
It is, however, part of my desire and effort to bring zero-cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Eight Sleep. Eight Sleep makes smart mattress covers with cooling, heating, and sleep tracking capacity.
Many times on this podcast, we discuss how in order to fall and stay deeply asleep, your body temperature actually needs to drop by about one to three degrees. And in order to wake up feeling maximally refreshed and energized, your body temperature needs to heat up by about one to three degrees.
Eight Sleep makes it very easy to control the temperature of your sleeping environment so that it's easy to fall and stay asleep and wake up feeling refreshed. I started sleeping on an eight sleep mattress cover several years ago, and it has completely and positively transformed my sleep. So much so that when I travel to hotels or Airbnbs, I really miss my eight sleep.
I've even shipped my eight sleep out to hotels that I've been staying in because it improves my sleep that much. If you'd like to try 8sleep, you can go to 8sleep.com slash Huberman to save $150 off their Pod 3 cover. 8sleep currently ships to the USA, Canada, UK, select countries in the EU, and Australia. Again, that's 8sleep.com slash Huberman. 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 plenty of the electrolytes, magnesium, potassium, and sodium, and no sugar. As I mentioned before on this podcast, I'm a big fan of salt. Now, I want to be clear.
People who already consume a lot of salt or who have high blood pressure or who happen to consume a lot of processed foods that typically contain salt need to control their salt intake.
However, if you're somebody who eats pretty clean and you're somebody who exercises and you're drinking a lot of water, there's a decent chance that you could benefit from ingesting more electrolytes with your liquids. The reason for that is that all the cells in our body, including the nerve cells, the neurons, require the electrolytes in order to function properly.
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Chapter 3: What actionable tools can improve REM sleep quality?
There certainly aren't a replacement for one another, but if you're doing physical exercise, meaning resistance training and cardiovascular training, and you're doing regular quality therapy of the sort that better help can provide, well then you're essentially doing as much as anyone possibly can to improve your mental health and physical health.
If you'd like to try BetterHelp, go to betterhelp.com slash Huberman to get 10% off your first month. Again, that's betterhelp.com slash Huberman. And now for my conversation with Dr. Matthew Walker. Dr. Matthew Walker, welcome back. Dr. Andrew Huberman, delight to be back.
During the course of this series, we've of course been talking about sleep and you've talked about the biology of sleep, ways to improve, maybe even optimize one's sleep. You defined what optimizing one's sleep actually is. Talked about learning and memory, creativity, caffeine, naps, food, exercise, and so much more.
excited that you're going to teach us about the relationship between sleep and emotion regulation but also mental health mental health challenges but i sometimes like to remind people that mental health includes the word health it's not all about mental illness it's also about how to improve one's health as well as ways to combat certain forms of mental illness or challenges so to start things off
Chapter 4: What role does sleep deprivation play in PTSD and anxiety?
If you could just give us the basics of the relationship between sleep and emotional states or one's ability to regulate their own emotions.
This is an area of work that we've been interested in and doing a lot of research on for about 20 or so years now. And I would say that probably the most striking statement I can offer up front is the following. In that 20 years of research, we have not been able to discover a single psychiatric condition in which sleep is normal.
And to me, it has taught me everything that I need to know about this very intimate bi-directional relationship between your sleep health and your mental health. And you're right to emphasize that notion of mental health because we're not just going to speak about some of the sort of challenging aspects of sleep and psychiatric disorders.
But we'll speak about some of the benefits that sleep can provide when you get it to turn the tables and we move in the direction not of mental illness, but we move in the direction of mental wellness. So I'm excited to sort of make sure that I don't fall prey to that.
Stepping back still though, what about this relationship between just sleep and our basic emotional regulation and our emotional stability? I'm sure everyone has seen the example or had the example as a parent of that parent holding a child and the child is crying and they look at you and they say, well, they just didn't sleep well last night.
as if there's some miraculous parental knowledge that bad sleep the night before equals bad mood and emotional reactivity and regulation the next day. And some years ago now, we were fascinated by this, but we couldn't really unearth basic science that would help us explain what was going on and why that was so clearly the case.
So we did an initial study where we took a group of healthy people, no signs of psychiatric illness or emotional instability, and we gave them a full night of sleep or we sleep deprived them. And then the next day we put them inside of a brain scanner and we showed them a whole range of emotional visual images ranging from very neutral all the way up to quite unpleasant and negative.
And we were looking at how the brain was reacting to those emotional experiences with versus without sleep. And the structure that we'd initially focused on was a structure that you've spoken about before called the amygdala. And you actually have one on the left and the right side of your brain.
And the amygdala is the centerpiece region for the generation of emotional reactions, both positive and negative. But here we're focusing on that aversive, that negative aspect. And when we looked at that structure in people who are sleep deprived, what we saw relative to the people who'd had a full night of sleep was a 60%, six zero, 60% increase in amygdala responsivity.
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Chapter 5: How does sleep relate to suicidality and depression?
if it's in the real world. But if you're at the movie theaters and you see a gun pointed in your face, your amygdala doesn't really react as much. Why? Because your prefrontal cortex understood the word that you described, which is context. But in some ways, it seems as though you become almost regressed to this more basic, fundamental, elemental, emotional brain.
And the red mist descends, and you really can't see much more because your prefrontal cortex seems to be absent.
You become very reflex-driven. And we don't want to go out too... far a tangent on prefrontal cortex, but one of the most beautiful descriptions of prefrontal cortex I ever heard was also from a colleague, Eric Knudsen at Stanford, who's now retired, does beautiful work on neuroplasticity. And he described how when people or animals have lesions to certain regions of the prefrontal cortex,
They become stimulus-driven machines such that if you go like this to a puppy or to a baby, they'll look to the snapping finger. But at some point, we all learn that there must be a reason for us to follow the snapping of the fingers in different locations in space.
Chapter 6: What are the effects of sleep on emotional regulation?
But with prefrontal damage – People and animals just become like machines. Whatever stimulus is there, they orient to. And this has implications for ADHD, et cetera. One of the things that I wanted to ask about to take us back to the specific relationship between sleep, reduced medial prefrontal activity, and emotionality.
is this feeling when we're sleep deprived that certain things just grate on us a bit more. You know, I had this experience recently. Unfortunately, there was a night where I didn't get much sleep at all.
And then the next day I was on a phone call and the person I was talking to, I'm quite fond of, but they had a lot of energy and they were talking, they're kind of coming at me with a bunch of stuff that they wanted to. And it just felt like, You know, it was grating on my system.
And I knew because I was sleep deprived that, you know, they were entirely well-meaning and so you just kind of resist. But it's incredible how cold water, loud noises, requests of our time, things like that become... very irritating and they grate on us when we're sleep deprived. Whereas when we're rested, it's like, oh yeah, okay. They're, you know, talking kind of faster, kind of loud. Okay.
Somebody is requesting something else. I'll put it in my list or maybe I'll defer to later. Or, you know, the, the cold shower that, you know, feels like, oh, got to get over the threshold to get into. Like when you're rested, you're like, all right, let's do this. Right. You know, maybe even let's go. I'm excited for it. But when you're tired, it is as if the, um,
The brain is fighting for any sense of peace it can possibly get, and that peace is interrupted by almost anything and everything.
It is a grim situation, and we've certainly heard that from patients and individuals. It's almost as though... the world that they are experiencing, they look at and they say, you know what? You're in an 11 and I need you at a seven right now. It is just too much. And this comes back to that result that we described that when the amygdala crosses the threshold,
and says, okay, things are getting emotional, things are getting unpleasant, I'm gonna be responding negatively in an angry way or a fearful way, that starts much earlier. So the threshold for triggering your emotional aversive reaction
is much lower and that's why the person's voice when you hear it at first normally if you had a great night of sleep you'd say gosh you know what today i really love your energy it's it's really it's so infectious versus a day when you're not sleeping you just think i just i'm lifting my earbuds out of my ears because i don't know if i can take this much longer and so
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Chapter 7: How can circadian misalignment impact mental health?
What that sort of turned a light bulb moment on for me was that somewhere between the initial experience and the later recollection of that emotional memory, the brain has done a very clever trick. It has divorced the emotion from the memory. So now when you come to recollect that emotional memory, let's say days later or even months later,
in some ways it is a memory of an emotional event, but it is no longer as powerfully emotional itself as it was at the time of the experience. And I started to wonder, is that time or is that time asleep? So we did a study and we had people experience these emotional memories, sort of essentially make emotional memories, and they were doing it inside of a scanner.
And then we gave them a night of sleep or even a nap. And then we brought them back or we just had them learn those emotional memories in the morning and then bring them back after an identical amount of time to try to soften those emotional memories, but without sleep.
we put them back in the scanner and we were able to look to see when you come back later in that second session is your emotional and you recollect those experiences and you relive them is the emotional reactivity at that second session any different to the first session and is that different if that time elapse has contained a full night of sleep versus you've just been awake
And what we found is that in those people who remained awake across the day, having had those emotional memories essentially implanted, implanted sounds a little bit sort of big brother, I don't mean it that way, but they'd learned them. the amygdala was just still as responsive as they were recalling and reliving and re-experiencing those emotional memories.
But in those people who had the same amount of time to process the memories, but had had a full night of sleep, we saw this incredible emotional amygdala depotentiation. And what that taught me was that the sleeping brain was able to almost detox the emotional memory.
Think about it like an informational orange, that the emotional memory has this bitter emotional rind around it, and then you've got the informational orange in the middle. And what sleep was doing was stripping the bitter emotional rind off the informational orange, so that then when you came back the next day, again, it is now a memory of an emotional event,
but it's no longer triggering that strong visceral reaction. In other words, and we describe this theory as something called overnight forgetting, which is that when it comes to an emotional memory, you both sleep to forget and sleep to remember respectively, which is that you sleep to remember the information, the memory of the experience, but it is no longer emotional itself.
And from there, we built a biological model of exactly how this works. Because when we looked at the sleep group who'd had that full eight-hour opportunity, we asked the question, because we'd measured their sleep, what is it about that sleep that seems to provide this form of, it's almost overnight therapy? How is it doing that? What stage of sleep is doing that?
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Chapter 8: What strategies can enhance overall sleep quality?
Yeah. And what they try to do is target in the brain these, you know, difficult, painful experiences and just excise them from the brain. And... That was the suggestion. Could you pop those memories out of the biography of that individual and save them the trauma?
I would argue that's not really what you want to do, because let's say that I am I have a trauma experience where I was walking home at night from the sleep laboratory late at night and I was coming down the kind of an alley to take a shortcut and someone sticks me up with a gun, maybe some violence. I don't want to remove that memory.
I would like to remove the trauma response associated with that memory. But I would argue for me as an organism, it's still very important for me to remember that that alley was associated with a bad experience and I should forego going down that very same route again. I want to hold on to the memory, the information. I want to let go of the emotion.
I want to sleep to remember, and I want to sleep to forget. And I'll come on to why I think that's relevant to PTSD when we perhaps speak about that condition, and it's very, very relevant. But coming back to REM sleep, We looked back in the literature to see if we could find signs that REM sleep had this relationship with even just your basic emotional reactivity.
And there was some wonderful work by a gentleman that you will know from Stanford, probably one of the founding fathers of modern day sleep research, a gentleman called William Dement.
Yeah, who passed away a few years ago. He did. Might have been one of the people who coined the term rapid eye movement sleep, but I don't think he was the one who discovered it, correct?
He was not, but he was well up there in terms of understanding both sort of what its term was and also what its function was. He, legend as he was, very early on, this was probably in the 60s, he would take individuals because we didn't really have the first published report of these two types of sleep, of REM and non-REM, until they collected the data or found the data in 1953.
It was published in 1954. So in other words, we discovered... that even up to then, prior to then, we just thought sleep was sleep. We didn't have any knowledge that these different stages. So in the same year that Francis Crick unveiled this incredible helical structure that was called a DNA strand, we also discovered the different stages of sleep.
But in the 60s then, William Dement, knowing that there were these two types of sleep and knowing that there was something that was going on with REM sleep where people were dreaming and he would be waking people up from these different stages and found that it's far more likely for people to report a dream.
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