The Matt Walker Podcast

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Rating
4.9
from
546 reviews
This podcast has
25 episodes
Language
Publisher
Explicit
No
Date created
2021/07/26
Last published
2022/06/20
Average duration
14 min.
Release period
14 days

Description

The Matt Walker Podcast is all about sleep, the brain, and the body. Matt is a Professor of Neuroscience at the University of California, Berkeley. He is the author of the book, Why We Sleep and has given a few TED talks. Matt is an awkward British nerd who adores science and the communication of science to the public.

Podcast episodes

Check latest episodes from The Matt Walker Podcast podcast

#24: Sleep is Bloody Remarkable - Part 2
2022/06/20
Matt is back this week with his recurring series, ‘Sleep is Bloody Remarkable’. Today’s episode is all about why we are unique when it comes to sleep.  When we compare our sleep to that of all other primates, humans stand out in two ways. First, we spend far less time asleep, and second, and in bloody remarkable ? contrast, humans get more than double the amount of REM sleep. Unlike many other primates, we humans are exclusively ground (or bed!) sleepers. In contrast, primates usually sleep arboreally, meaning in the branches of trees. During REM sleep, to prevent acting out our dreams, the brain paralyzes the body. But this is far too dangerous to do if you are sleeping up in the trees, lest you fall fatally down to earth. Homo erectus, as the first obligate biped and, with fire to deter predators and blood-sucking insects, was able to sleep fairly safely on the ground. However, fire didn’t eradicate all the risks. This forced another [bloody] remarkable change: hominids had to become far more efficient in their sleep and thus shorter duration of sleep.  This re-engineering of human sleep became one of the triggers that rocketed Homo sapiens to the top of the evolutionary pyramid due to REM sleep’s supercharging of 1) our socioemotional, allowing us to form the cooperative societies that formed the basis of modern civilizations, and 2) cognitive intelligence, particularly our creativity, which was the fuel to our brain-derived engine of ingenuity that helped in the great advances of civilization.  “Simply put: we sleep, therefore, we are.”  Sleep really is bloody remarkable.  Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. One of the sponsors of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. So, if you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. Another sponsor of the episode today is our good friends at the athletic clothing company, Vuori. They have a special deal where you can get 20% off your purchase when you visit vuori.com/mattwalker. Vuori produces high quality clothing, and they offset their carbon footprint 100%, both of which, of course, mean a great deal to me. So, if you like athletic clothing, and you wish to help the planet out, then check them out at vuori.com/mattwalker and get 20% off your purchase.    So, make your way over to LMNT and Vuori to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#23: Dreams – Part 6
2022/06/06
In this episode, Matt goes deeper into his exploration of  lucid dreaming. He tells us all about studies demonstrating that lucid dreamers can wake from dream sleep on command, demonstrating control over intention in their dreams, and even bring themselves to orgasm in dream sleep! Matt tells us about two leading methods for developing the skill of lucid dreaming. The first is Mnemonic Induction of Lucid Dreams, which involves the creation of a conscious, deliberate intention to remember that one is dreaming. For example, repeating a certain phrase each night before sleep. The second is the Reality Testing Method. This involves consistently examining one’s environment and testing to differentiate between which of the two worlds, waking or dreaming, it is. The idea is to ingrain these tests in your waking life, so that they will flow over into your dreams, thereby triggering lucidity if you are dreaming. But how does the brain become lucid during dreaming? It’s been discovered that when lucid dreaming starts, the prefrontal cortex fires up into activity! This seems to be a defining quality of the lucid dreaming state, different to classical REM sleep dreaming where this rational control region of the prefrontal cortex re-engages, thereby letting you gain volitional control over what you dream. Matt finally poses this hypothesis: between 80 to 90 percent of the populace are not lucid dreamers. If gaining dream control was so beneficial, surely more of us would do it. However, Matt counters his own argument: as we have not stopped evolving, it’s possible that lucid dreamers represent the next iteration of hominid evolution in their ability to control their dreams, and potentially harness their preferred creative problem-solving ability! #mindblown! Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth. So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#22: Dreams - Part 5
2022/05/23
In part five of his series on dreams, Matt discusses what lucid dreaming is and how it was scientifically proven to be real. We define lucid dreaming as the moment when an individual becomes aware they are dreaming. Historically, the concept of lucid dreaming was considered a scientific scam. First, to claim that people can gain conscious control over a normally unconscious process injects a heavy dose of ludicrous into the already preposterous experience we call dreaming. Second, how could any scientist objectively prove a subjective claim, especially when the individual is asleep when they do it? Well, several years ago, an experiment removed all such doubt. Lucid dreamers were placed inside an MRI scanner and instructed to alternately clench their hands. The researchers took snapshots of their brains as they were doing this, allowing them to define the precise  areas controlling each individual’s left and right hand. In the second part, the participants again underwent an MRI scan, this time, allowed to enter REM sleep. Once the subjects became lucid, they signaled their awareness with a specific set of eye movements so researchers could take MRI pictures of brain activity. They then gave another set of eye signals to demonstrate that, in the dream, they were now alternating between clenching their hands. Each time the dreamers indicated that they were clenching a hand, the scientists were able to take down timestamps. Of course, the participants weren’t physically moving their hands, but amazingly, the results of the MRI scans proved that they weren’t lying; the same regions of the brain that were active during the physical movements lit up when the lucid dreamers clenched in dreams. With these results, the scientists had gained objective proof that lucid dreamers can not only control when they are dreaming but can also control what it is they dream. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. One of the sponsors of the episode today is our good friends at the athletic clothing company, Vuori. They have a special deal for you all where you can get 20% off your purchase when you visit vuori.com/mattwalker. Vuori produces high quality clothing, and they offset their carbon footprint 100%, both of which, of course, mean a great deal to me. So, if you like athletic clothing, and you wish to help the planet out, then check them out at vuori.com/mattwalker.  Another sponsor of today's podcast is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can fully get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities important to maintaining your blood biochemical balance. So, if you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#21: Dreams - Part 4
2022/05/09
Today’s episode focuses on a second but very different function of dreaming: the ingenious processing and interconnection of memories that inspires creativity and even problem-solving ability. Matt describes how we can think of REM sleep dreaming as a form of informational alchemy, in which we build new connections. As a consequence, we wake the next morning with a mind-wide web of associations capable of divining solutions to previously impenetrable problems. A great illustration of dream-inspired creativity is the chemist Dmitri Mendeleev, who had been trying for years to solve arguably the greatest problem of his time: how do all of the elements in the universe fit together? When Mendeleev finally lay down to sleep, his dreaming brain came up with the Periodic Table. It’s not just in the sciences that we’ve seen dream-inspired insight. Consider, for example, Sir Paul McCartney’s origination of the songs “Yesterday” and “Let It Be,” both of which came to McCartney in his dreams.  Matt and his team conducted a study which found that participants were 30% better at solving cognitive problems when they were woken up out of a REM sleep dreaming state. Moreover he found that the way you solve problems is different when you’re coming out of REM sleep dreaming. Matt suggests that this reflects the biological basis of creativity. Importantly, it’s not just that you dream, but once again, what you dream about that seems to matter. Little wonder then we’re never told to, “stay awake on a problem.” Instead, we’re told to 'sleep on it'. That phrase, or something close to it, seems to exist in most languages that Matt has enquired about, indicating that the problem-solving benefit of dream sleep is universal. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth. So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#20: Dreams - Part 3
2022/04/25
Matt’s back with part three of his series on the science of dreaming! In this episode, he discusses how he and other scientists have discovered that dreams are not simply an  unintended by-product of REM sleep. Instead, dreams provide at least two essential benefits for human beings. The first of these functions involves nursing our emotional and mental health and is the focus of this episode. Matt helps us understand that what makes a memory emotional is that, at the time of the experience, we release a visceral, emotional reaction. This wraps itself around the memory and red flags that memory/experience as important, and tags and bonds itself to the information, creating an “emotional memory.”  Years ago, Matt and his team discovered that it’s not time that heals all wounds. Instead, it is sleep, that helps the brain divorce the emotion from the memory, offering what Matt has described as, “a form of overnight therapy.” Dreaming of these emotional events allows mental-health resolution, keeping our minds safe from the clutches of anxiety and reactive depression. Earlier work by pioneering researcher Dr. Rosalyn Cartwright addressed the latter condition of depression. Her remarkable work studied the dreams of people showing signs of clinical depression due to difficult emotional experiences. Through her research, Dr. Cartwright found that only those patients who had been dreaming about their painful experiences went on to gain clinical resolution from their depression.  When it comes to resolving our emotional difficulties it’s not enough to have dreams. Instead, we seem to need to dream of the events themselves to benefit from that emotional therapy.  Now if you’re not remembering dreams of difficult experiences you’ve been going through, don't worry. If Matt brought you into his sleep center and woke you while you were having REM sleep, your dream reports would most likely reflect that you are doing exactly what you need to be doing in terms of your emotional processing. In other words, all of this work tells us that one of the functions of dreaming is to serve as a set of emotional windscreen wipers! As a result when we wake the next morning after a night of dreaming, we are dressed in a very different set of psychological clothing to that we went to sleep in--a less ruffled emotional outfit, free of the sharp creases of painful emotions. What Matt and his team discovered is that it’s not time that heals all wounds, but rather, it is time spent in dream sleep that provides emotional convalescence.  To sleep, perchance, to heal. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this particular episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.
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#19: Dreams - Part 2
2022/04/11
In the second episode of this series about REM sleep dreaming, Matt explores what the science has to say not only about how we dream at the brain level, but what it is that we dream about.   Traditionally, civilizations such as those in ancient Egypt, believed that dreams were a form of divine intervention--a message from the heavens. Thereafter, Matt discusses Sigmund Freud, who introduced the notion of dreams originating from within the brain, not the heavens, and thus could be considered a science of the brain/mind. However, Freud went on to develop the (non-scientific) theory that dreams reflected the expression of our subconscious desires, but that those repressed wishes were transformed and disguised by the brain into a dream narrative. Freud's theory suggests that, as we dream, our repressed wishes pass through a sensor in our mind, and then come out the other side as unrecognizable experiences to the dreamer.  Freud believed that he understood how the sensor worked and could decrypt the disguised dreams, and thus know something about his patients that he could share with them. Matt notes that Freud's theory could never be proven right, nor wrong, and also why we no longer consider it as a valid scientifically rigorous theory. Next, Matt delves into modern-day scientific methods that have led to new theories of why we dream, including a theory that dreams are a replay of our waking life experience of our past memories.  He recounts the work of his friend, Dr. Robert Stickgold, who found that only 1 to 2% of our dreams are really true clear replays of our prior waking life events. Matt also notes that, based on the same findings, there is a red thread narrative that runs from our waking lives into our dreaming lives = emotional concerns that we're having during the day, and the social individuals connected to those things. Matt describes the latest research from a team in Japan that used MRI scans to predict the content of dreams. Matt postulates that science is getting ever closer to having the ability to know exactly what we are dreaming, and perhaps, take away ownership of the dream process from the dreamer itself. Matt draws this episode to a close by asking some thought-provoking questions about whether we are truly responsible for what we dream about, and whether we should be held responsible for what we dream. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth. So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#18: Dreams - Part 1
2022/03/28
This week’s episode is the first in a new multi-part series all about dreams! Today, Matt focuses on the question of how your brain generates these things called dreams. Matt starts with an unexpected statement: last night, when you were dreaming, you became psychotic. 5 things happen when you dream that justify his diagnosis: 1)  you see things that aren’t there, 2) you believe things that could not be true, 3) you become confused about time, place, and person, 4) you have wildly fluctuating emotions, and 5) you wake up in the morning and forget most of this dream experience, amnesia. If you experience any of these symptoms while awake, you might seek psychological attention. Yet,  dreaming is both a normal and, essential biological and psychological process. Matt explains that REM sleep is not the only stage of sleep when we dream. However, the things that most of us call dreams, involving movement, emotions, past memories, and rich narrative, largely come from REM sleep.  Over the past 20 years, a new scientific view of REM sleep has given rise to an understanding of 3 basic questions regarding dreaming. 1) how does the brain create this neural activity called dreaming? 2) can we explain if dreams have their source in our experiences, or are they de novo experiences generated by the brain? 3) what is the function of REM sleep dreaming? The advent of brain-imaging machines allowed scientists like Matt to create beautiful 3D visualizations of people’s brains as they dreamt. When the brain switches from deep non-REM sleep over to REM sleep, something remarkable happens: the brain erupts with spikes of activity in the MRI scans. Specifically, 4 areas of the brain fire up when dreaming starts during REM sleep: the visuospatial regions, the motor cortex, the hippocampus, and the amygdala. In contrast to all of these areas, one part of the brain does the opposite. The left and right sides of your prefrontal cortex becomes markedly deactivated during REM sleep. This is important because your prefrontal cortex controls logical reasoning. This is, in part, why dreams are often filled with movement, strong emotions, past memories, people, and experiences, yet are utterly irrational.  Finally, Matt reminds us of one last fact. When we are in REM sleep dreaming, the body is paralyzed, preventing us from acting out our bizarre dreams. Otherwise, we would put ourselves in danger and be popped out of the gene pool rather quickly! Be sure to tune in for the rest of the series to uncover even more fascinating information about these things we call dreams. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering a special 31% off any one of their programs if you use the above link during the time window of this particular episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.
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#17: Sleep is Bloody Remarkable - Part 1
2022/03/14
Matt has a special announcement this week: a new recurring type of episode called, ‘Sleep is Bloody Remarkable’. This series of episodes will share fascinating facts about sleep that will  blow your mind! In the premier episode, Matt focuses on something truly (bloody) remarkable: half-brain sleep, or unihemispheric sleep.   Unihemispheric sleep is the phenomenon of when one hemisphere of the brain is awake, while the other sleeps. Matt goes on to discuss how the two sides of the brain rotate their sleep roles, such that after a set period of time, the side that got to undergo sleep first wakes, so that the other half of the brain gets its needed opportunity for sleep.   Whales and dolphins are great examples of half brain sleepers. They need to maintain movement in their underwater environment. Half-brain sleep allows them to still do this while still getting plenty of NREM slumber (just one half of the brain at a time).  Birds are also capable of half-brain sleep. Birds use unihemispheric sleep for survival purposes, although for different reasons. Birds use it to keep one eye on things, literally!   When birds land as a flock, the birds on the farthest left and right sides - the sentinels, as it were - undergo unihemispheric sleep, to keep one eye open for threat detection on their respective side (180 degree views on the left and right). The result being, combined, the entire flock gets full 360 degree panoramic threat detection. Indeed, all of the rest of the birds are allowed to sleep with both hemispheres i.e., full brain sleep. The poor birds on the sides don’t actually get the chance to come into the middle of the flock, it seems. Instead, to get equal sleep on both sides of the brain, when one hemisphere has fulfilled its sleep need, these birds will rotate 180 degrees, and switch sides of the brain that is sleeping. Bloody remarkable!  We humans undergo our own rendition of unihemispheric sleep…sort of =)  In an unfamiliar location, such as a hotel room, humans keep one of their hemispheres on guard in this potentially dangerous context. Meaning, one half of the brain does not go into as deep NREM sleep, almost as if it is remaining semi-conscious. Matt also notes that half-brain sleep only happens during NREM sleep. When all species go into REM sleep, both sides of the brain sleep. There is no unihemispheric dream sleep, it seems.  Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth. So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.
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#16: Sleep & Weight Gain – Part 2
2022/02/28
Matt returns with Part 2 of his series on sleep and weight gain. This time around, he teaches us how a lack of sleep not only makes you eat more food, but changes what types of food you want to eat, and eat to excess. First, Matt describes how underslept individuals that are limited to 4-5 hours of sleep for several nights will experience a 33% increase in the desire to eat obesogenic, sugary treats. In addition, they will suffer a 30% increase in craving for heavy-hitting carbohydrates, like pasta and pizza, and a 45% increased desire for salty snacks! Matt goes on to explain that your brain plays a role in this sleep loss-weight gain equation. In one of his experiments, a group of normal, healthy-weight individuals went through the study twice: once when sleep-deprived and once after a full night of sleep. After each condition, the individuals were placed inside an MRI scanner and shown different food types, and asked to rate how much they wanted each food item.  What they found is that the sleep-deprived brain changed markedly, shifting to a pattern of activity associated with what is called hedonic eating, or impulsive eating. Specifically, the prefrontal cortex, which is responsible for impulse control, was shut down by lack of sleep. As a result, the very primitive deep brain regions that drive excessive appetite become hyperactive and hyper-responsive to highly desirable, unhealthy food items, such as ice cream and donuts, rather than nuts or leafy greens. He also reveals that staying awake across the night doesn't burn vastly more calories. You only burn about an extra 140 calories by staying awake all night relative to being asleep, yet you will eat more than twice that amount more in calories when sleep-deprived. Plus, you are less active when sleep-deprived, so you don't burn off those calories.  Worse still, Matt tells us that dieting becomes ineffective without sleep: 60% of the pounds you will lose come from lean body mass (such as muscle), and not fat.  Specifically, when you are sleep-deprived, the body becomes especially stingy with fat, stubbornly refusing to give it up. In other words, you end up losing what you want to keep, which is muscle, keep what you want to lose, which is fat. Also, inadequate sleep increases levels of cortisol, which also makes your body store food as fats. Matt concludes with an optimistic note by highlighting the fact that getting enough sleep is a scientifically proven way to help you regulate your appetite and a healthy body composition (a little bit less painful than going to the gym!?) Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.
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#15: Sleep & Weight Gain – Part 1
2022/02/14
Matt kicks off a two-part series all about sleep, eating, and weight gain.  He starts by introducing two appetite-regulating hormones: leptin and ghrelin. Matt explains how leptin sends a signal of fullness, to your brain. When leptin levels are high, your appetite is reduced, and you feel satisfied by the food you eat. Ghrelin does the exact opposite. It revs up your hunger, so when your ghrelin levels are high, you don’t feel satisfied by the food you ate, so you want to eat more. Matt tells us that when you’re not getting enough sleep, the levels of these two hormones are affected in unfortunate ways, causing you to feel less full and more hungry. Specifically, sleep loss decreases leptin levels by 18%, yet increases ghrelin levels by 28%! So when you are not getting enough sleep, the body losses the fullness signal AND suffers an increase in hunger levels. The combined consequences? Your appetite rockets up! It’s also been discovered that levels of endocannabinoids --a class of cannabinoids we naturally produce ourselves -- increase sharply in response to a lack of sleep. As a result,  your hunger levels increase even more (as you may know, cannabinoids are part of the reasons that cannabis gives you the munchies). Adding up all of these effects, Matt describes how this lack of sleep causes people to consistently overeat. Usually somewhere between 250 to 400 extra calories each and every day! Snacking also becomes a problem. For example, if you present a group of people with a large meal of over 1,000 calories, then give them the option to keep snacking,  under-slept individuals will continue to snack, consuming an additional 200 to 300 calories relative to those who’ve been getting a full eight hours of sleep. This all begs the question: is there a reason why your hunger goes into overdrive when you are under-slept? Matt explains one plausible theory from an evolutionary perspective, based on the fact that when animals are in a starvation state, the brain keeps them awake longer so they can forage further. Therefore, when the brain doesn’t get enough sleep, it thinks we may be in a state of starvation and increases our desire for food. Finally, notes what's coming in part two:  that insufficient sleep not only increases how much you eat but changes your food preferences, and changes how your bodies deposit the extra calories we take on as our hunger increases, relevant to body fat accumulation. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at Athletic Greens are the sponsors of this week’s episode, and they are generously offering three benefits for anyone who uses the above link for their first order: 1) a discount on your order, 2) a one-year free supply of vitamin D, and 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals, and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health and uses it as a full nutritional insurance policy, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks it’s science and scientific data that can be taken as ground truth. So, make your way over to Athletic Greens, and take advantage of this incredible deal. And, as always, if you have thoughts you’d like to share, please reach out to Matt on
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#14: Temperature – Part 2
2022/01/31
In the previous episode, Matt described the role of temperature in helping us fall asleep. In this episode, Matt teaches us all about the role of temperature in helping us stay asleep across the night, and then more effectively wake up the following morning. First, Matt takes us back to the body temperature suit experiments that were able to warm or cool different parts of the body. Matt explains that, using this same method, when you continue to cool the body throughout the first and middle parts of the night, enhance the ability of individuals to stay asleep more soundly across the night, increase the amount of deep sleep, and boost the electrical quality of that deep sleep. Matt explains why a warm bath or shower before bed helps you sleep, perhaps for the opposite reasons you think. It is not that you get warm and toasty ready for bed. Instead, when you get out of the bath or shower, all of the blood races to the surface of your skin. As a result, your core body temperature plummets, enabling you to fall asleep faster and stay asleep more easily. Matt also discusses how external ambient room temperature impacts our sleep at night. He notes that the optimal temperature for sleep at night for the average adult is between 16-18 degrees Celsius, or 61-65 degrees Fahrenheit, although everyone will be a little bit different, of course. Finally, Matt explores the effect of temperature on waking up. He notes that as you move into those late morning hours of sleep, particularly as you start to enter the REM sleep-rich phases of your sleep cycle later in the morning, your central brain temperature rises significantly.  Indeed, it is in the last 30 minutes before people would naturally wake up in the morning that their body temperature starts to increase markedly. Matt goes on to describe how this increase in temperature is a signal that triggers the beginning of the awakening process. Related to this, Matt notes that waking up can be challenging for many people, especially if you're not sleeping in synchrony with your chronotype. However, Matt suggests that one way you can facilitate the process of waking up more effectively is by trying to warm up the ambient temperature of the bedroom in the last 30 minutes before your alarm goes off. So if you have a smart thermostat, try to program it to increase the temperature to around 21 degrees Celsius or approximately 70 degrees Fahrenheit in the last 30 minutes before your alarm goes off. The bottom line is that many of us don’t realize how important temperature is to falling asleep, staying asleep, and enjoying an enlivened awakening the next morning. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.
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#13: Temperature - Part 1
2022/01/17
In today's episode, Matt reveals how 1) your own temperature and, even more precisely, 2) the temperature of different parts of you, as well as 3) the temperature of your bedroom, can change how well or how poorly you sleep at night. Matt describes the basic physiology of how your brain and body needed to drop their core temperature by about 1 degree Celsius, or about 2 to 3 degrees Fahrenheit, for a person to fall and stay asleep across the night. This is the reason why we will always find it easier to fall asleep in a room that's too cold than too hot because the room that's too cold is at least taking you in the right temperature direction for good sleep at night. Matt teaches us that, ironically, one important way to drop your core body temperature is to warm up your extremities, specifically your hands and feet. He explains that it's one of the key ways your body regulates temperature.  To drive his point home, Matt points to research showing that if you gently warmed the paws of rats, it encourages the blood to rise to the surface of the skin of those paws, away from the core of the body.  By emitting heat away from the body's center, it drops core body temperature rapidly, and as a result, the rats drifted off to sleep far faster than was otherwise normal. Matt complements all this with a study in humans using a whole-body temperature sleeping suit, a little like wetsuit, but with tubes throughout that can warm or cool different parts of the body with warm or cool water.   In the first series of studies, researchers selectively warmed the feet and the hands by just a small amount, which caused a rising of the blood to the surface of the skin. As they warmed the body's extremities, the core temperature of the participants dropped, and the upshot was that these healthy individuals were falling asleep 20% faster than was normal. In the second round of studies, even more remarkable, if you manipulate the temperature in this way in older adults, they will fall asleep 18% faster than typical, and insomnia patients will fall asleep a full 25% faster than usual with this same method.  The impact of temperature on sleep is therefore clearly significant, but there is even more to this thermal story, including how you can best wake up from sleep feeling alert, which is what Matt will discuss next episode.  Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way. The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic. So, head on over to Athletic Greens and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram.
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Podcast Reviews

Read The Matt Walker Podcast podcast reviews

4.9 out of 5
546 reviews
Luna the Night Owl 2022/06/19
Enthusiastic and educational
This short-style podcast is educational, based in science, communicated so all can understand easily whether their background is in the sciences or no...
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mzmatai 2022/06/11
Sleep is therapy!!!!
I found out about Dr. Matt Walker through Sam Harris’ Waking Up app, and the episodes on The Kingdom of Sleep! I listened to them all and am so impres...
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DeniseW1955 2022/06/08
love the sleep series--more please
I think you only touched the surface of what we know. I would appreciate a deeper dive into sleep and dreams since you are one of the foremost experts...
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Jacquelyn M Higgins 2022/05/29
Thank you!
I first heard you on the Megyn Kelly Show. and learned so much. This is such an interesting podcast and has been helpful for understanding sleep and h...
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sbannmarie 2022/05/23
“After all, I’m British”
And so Matt humbly and succinctly speaks. Great podcast, keep ‘‘em coming!
Amaholic5 2022/05/09
Easy Listening and Interesting
Matt speaks with slow, calming, and articulate prose. Helps me relax, learn about sleep one of my favorite topics, and focus on health. The book is ...
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DMR525 2022/05/01
Matt Walker Never Disappoints
I have been following Dr. Walker and his research for years. As always, his way of breaking down complicated neurological/scientific data is brilliant...
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ukiddin 2022/04/30
love this doc
he is fantastic! I learn so much
ashwilt 2022/04/28
Fascinating podcast!
Appreciate how clearly Matt Walker explains the science of sleep. Informative, interesting, and entertaining too! I don’t mind the longer episodes at ...
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GB_GB 2022/04/15
Before I even listened
You are an absolute delight! I’ve been watching your interviews religiously and just came across the one with Andrew Huberman. I’m so excited you got ...
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