In today's episode, Matt unpacks the world of coffee, and caffeine in the first of a two-part series on caffeine. Matt describes the numerous health benefits associated with coffee, the fact that Matt has even changed his tune a little and advocates a morning cup for some. Matt may not have anything to do with caffeine itself, with more details on that in part 2. In part 1, Matt then takes a deep dive into the different ways in which caffeine negatively impacts your sleep, some of which you may be less familiar with.The first is that caffeine makes it harder for you to fall asleep. Due to activation of the nervous system, caffeine can lead to that unpleasant experience of a racing mind that won't shut off in bed—almost a Rolodex of anxiety that leads to ruminating and therefore catastrophizing.The second impact is that caffeine makes it more difficult for you to stay asleep soundly across the night. This is due, in part, to the fact that caffeine makes your sleep more unstable and fragile, so  up more frequently at night. The consequence is something that scientists and doctors call sleep fragmentation, meaning that your overall sleep efficiency, or the consistent quality of your sleep, becomes significantly worse when you have caffeine on board.The third feature that Matt points out centers on caffeine’s duration of action. Caffeine has a half-life of between five to six hours in the average adult. This means that, after five to six hours, 50% of that caffeine is still in your system. What this also means is that caffeine has a quarter-life of approximately 10 to 12 hours for a typical adult. Here, Matt gives us some context: if you have a cup of coffee at 2 PM, a quarter or more of that caffeine could still be circulating in your brain at midnight. Meaning, if you have a cup of coffee at 2 PM, it may be the equivalent of getting into bed at midnight, and just before you turn the lights out, you swig a quarter of a cup of coffee and you hope for a good night of sleep.Matt, however, points out that the 10 to 12 hours quarter-life of caffeine is for the average adult, but this varies significantly from one person to the next. He explains in detail why this is the case: based on differences in genetics, different people will have a more or less efficient version of an enzyme that clears caffeine from their system. Some people will have a version of that enzyme that allows them to remove the caffeine from their system very quickly, whereas other people will have a version of the enzyme that is much slower in its speed of clearing caffeine.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.

On last week’s episode, we learned about the three main ways alcohol can harm our sleep: 1) alcohol results in sedation rather than naturalistic sleep, 2) alcohol causes sleep fragmentation, and 3) alcohol impairs REM sleep. Today, Matt dives into each of these negative impacts, explaining exactly how and why alcohol disrupts our sleep in these specific ways.First, alcohol is a class of chemicals called “the sedatives,” and sedation is not natural sleep. Healthy sleep is a very active, highly coordinated event within the brain, unlike sedation. As a result, alcohol can result in you waking up and feeling unrestored and unrefreshed by that non-normal sleep. Second, we normally need to shut off our fight-or-flight branch of the nervous system, called the sympathetic nervous system, and shift over to the calming, parasympathetic nervous system, in order to stay asleep soundly across the night. However, alcohol reactivates the fight-or-flight nervous system, forcing the brain and body back into a more hyper-alert state. This increases the chances of you waking up and staying awake, causing your sleep to become more fragile and prone to fragmented awakenings throughout the night. Alcohol also triggers the release of several stress-related chemicals, including cortisol. This stimulates the fight-or-flight nervous system and emotional centers in the brain, also making it more likely that you will wake up and stay awake.Finally, alcohol significantly reduces the amount of REM sleep the brain can produce. Specifically, the metabolic byproducts of alcohol degradation within the body disrupts and impairs the generation of REM sleep. Without that REM sleep, we can suffer impairments to our cognitive brain function and emotional stability. We can also experience a heightened amount of negative moods, such as anxiety. REM sleep is also the time when we hit our peak in the release of important hormones, like testosterone, which is critical for both men and women.While Matt acknowledges that this news may not be especially encouraging or popular, he closes out today’s show with a reminder that life is to be lived. It is not his intention to tell anyone how to live their life. Instead, Matt’s goal is to simply lay out the scientific evidence regarding the relationship between sleep and alcohol, so that you can make an informed decision about how to best structure your own sleep schedule and find an enjoyable life balance.Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as 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 www.athleticgreens.com/mattwalker 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 @drmattwalker.

Although some people may believe that a drink or two in the evening will help them sleep better, today’s episode shows us that alcohol harms our sleep in several different ways. In the first of two episodes on sleep and alcohol, Matt talks about alcohol as a chemical, and the main ways it negatively affects our sleep.Alcohol has a sedative effect that switches off brain cell firing as we sleep. Alcohol also fragments our sleep, making it less restorative, and blocks REM sleep, which is critical for numerous aspects of health and wellness, including learning and memory, creativity, rebalancing moods and emotions, recalibrating certain hormone systems, and even lifespan longevity.Matt describes the clock-counter system our brains use to track lost REM sleep, and why we sometimes experience strong, intense and vivid dreams in the late hours of our sleep after too much alcohol as a result. In today’s episode, you’ll also learn about the specific ways in which alcohol interferes with our sleep quality, and the different stages of our sleep, REM sleep especially. Be sure to tune in next week as Matt further examines exactly what it is about alcohol that disrupts our sleep in these particular ways, and what the consequences are on health and wellness.Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as 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 www.athleticgreens.com/mattwalker 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 @drmattwalker.

As the great Roman poet, Ovid, once said, “There is more refreshment and stimulation in a nap, even of the briefest, than all the alcohol ever distilled.” But are naps always a good thing? Are we even designed to nap? And if you do nap, when should you do it, and for how long? Today Matt explores the benefits and pitfalls of napping, how napping may fall in line with our pre-programmed sleep patterns as humans (a natural drop in alertness between 1 and 4pm each day), and what it means if you find yourself waking up from an accidental nap on the couch right before bed. You’ll also hear about the NASA nap culture, sleep inertia (which can include a feeling of a “sleep hangover”), and Matt’s advice for how to use naps to your advantage. If done correctly, for most people not struggling with sleep or insomnia, naps can improve alertness, task performance, creativity, and even reduce blood pressure. However, there is a dark side to napping that Matt discusses in detail, and why that can be the case. So join Matt as he walks you through both the advantages and disadvantages of napping!Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as 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 www.athleticgreens.com/mattwalker 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 @drmattwalker.Detailed Scientific LiteratureNaps and overview (by the amazing Prof. Christopher Barnes)The good and the bad of napsNaps and MortalityNaps, Brain function & Performance​​

In the final episode of our three-part series about chronotypes, Matt examines the question of  whether your chronotype is truly fixed, or if you can change an evening type to a morning type (though you will hear that Matt’s preference is for society to change, not the individual). Matt reviews a fascinating study by an Australian-lead research team that tried to turn night owls into morning larks. Participants had to follow a series of strict rules over the course of a three-week study. This included things such as: setting an alarm to wake up two to three hours earlier than their normal wake time, eating breakfast first thing after waking up, getting outside for as much natural daylight as possible, and not having any caffeine after 3pm. As you’ll hear from Matt, the experiment was...somewhat successful. By the end of the study, evening types went to bed about two hours earlier than usual, managing to get to be around 12:30am, instead of 2:30am. In addition, their performance on several standardized cognitive tasks also improved expressly during the morning hours, when night owls typically struggle the most. However, as Matt points out, participants were still opting to go to bed after midnight, which is far from morning night-owl-like, and far from being turned into a morning type. It is also unlikely these individuals could continue with this rigid new set of experimental guidelines across the long-term, for their entire lifespans.In other words, the results are fascinating, but the practice itself may not be sustainable in the real world. Instead, Matt's wish is that we simply allow evening types to sleep in harmony with their genetic chronotype. If night owls were able to sleep and wake up when they are biologically designed to, the world would be a happier, healthier place indeed.Please note that Matt is not a medical doctor and none of the content in this podcast should be considered as 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 www.athleticgreens.com/mattwalker 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 @drmattwalker.Basic Resources Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)Scientific Review: Biological Rhythm and Chronotype

In the second episode of our three-part series on chronotypes,  Matt speaks about what happens when you do not sleep in harmony with your natural chronotype. Unlike morning larks, night owls simply cannot fall asleep easily early at night, which leads to the first and most obvious consequence of not sleeping in line with your chronotype—you don’t sleep as much.Matt explains that morning types sleep over 7-hours per night on average, while evening types can only manage 6.6-hours of sleep per night. Matt also notes the upshot, which is a chronic “sleep debt”, one that accrues night after night, month after month. The ramifications are many, including increased caffeine intake for evening types, higher likelihood of developing hypertension and Type II Diabetes, and greater difficulty maintaining a healthy body weight. In addition to these consequences to the body, evening types are two to three times more likely to develop depression than their morning type counterparts, and twice as likely to be using antidepressants. Matt clarifies that his intent in sharing the concerning statistics is not to worry evening types, but rather, to help them realize their true biological nature, and as important, not feel guilty for it. Today’s episode aims to vindicate and empower evening types with the knowledge that they may be sleep deprived, and to help them find a schedule that falls in line with their natural chronotype.Matt Finally speaks about current societal practices that push (actually, force) night owls into unhealthy sleep rhythms. He outlines his (lofty 😊) goal of restructuring the typical schedule of work in first-world nations, which is strongly biased toward early start times that incorrectly punish night owls and favor morning larks. Matt notes that this is markedly unfair, since it is not their choice as to which ‘type’ they are. Instead, it is their pre-ordained, genetic-based sleep chronotype, yet society wrongly assumes that evening types could get up earlier if only they weren’t so slovenly. Of course, the science and this episode tells us otherwise.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 www.athleticgreens.com/mattwalker 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 @drmattwalker.Basic Resources Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)Scientific Review: Biological Rhythm and ChronotypeScientific Review: Chronotype and Mental Health: Recent Advances

Episode 04: Chronotype: Part 1SummaryAre you a morning type? Or are you an evening type? Perhaps you are neither of the two? Today’s episode is the first in a three-part series all about your chronotype, or your body’s natural biological preference to be awake and be asleep at a certain time. Matt begins by explaining exactly what your chronotype is, then breaks down the three main “flavors” of chronotype (morning lark, night owl, or somewhere in-between). In addition, and listed in the show notes, below, he explains how to determine whether you are a night owl or a morning lark. He will also describe how an individual’s sex falls into the equation and the difference between your chronotype and your circadian rhythm. You’ll hear about the key ways in which evening types biologically differ from morning types, that your chronotype isn’t your own choice nor is it your own fault, but rather, there is a very strong genetic basis of why and how you are programmed in terms of being a morning or an evening type? Today’s main takeaway is that when you or when society tries to force you to sleep in opposition to your biology, there can be unfortunate consequences. Stay tuned as we explore these in greater detail next time.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 www.athleticgreens.com/mattwalker 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 @drmattwalker.Basic Resources Discover your chronotype: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)Scientific Review: Biological Rhythm and ChronotypeScientific Review: Chronotype and Mental Health: Recent Advances

#03 Circadian RhythmsContinuing on from last week’s episode about sleep pressure, today, Matt Walker dives into the second half of the sleep-wake story, circadian rhythm. Matt explains that your circadian rhythm, or your 24-hour internal clock, begins drumming out its loud activating beat just before you wake in the morning and gets louder throughout the day, peaking in the early afternoon and hitting its lowest point in the middle of your sleep phase overnight. Matt describes how circadian rhythm and sleep pressure work independently of one another, yet coincide with a beautiful synchronicity to naturally and gently rouse you from sleep in the morning and rouse you into full wakefulness, then pull you into a wonderful, restorative sleep at night. You’ll also hear about the reliable mid-afternoon drop in alertness we see each day, what this means in terms of how humans were designed to sleep, and why it may explain the occasional need for a siesta._________________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  www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts on sleep topics that you want Matt to cover, or you have feedback you’d like to share so he can be better at podcasting, please reach out to Matt on Instagram @drmattwalker. He'd love to hear from you🤗!

Episode 02:  Sleep PressureWelcome back to the Matt Walker podcast. Today’s episode looks at the story of sleep pressure - how it works, how you can try to block it or fool it, and why you feel so good after a night of full, peaceful sleep. Matt explains that from the moment you wake up, a chemical called adenosine begins to build up in your body. The longer you’re awake, the more adenosine will build up and the sleepier you will feel. This is called sleep pressure. Once adenosine concentrations peak, usually after about 12-16 hours of being awake, the irresistible urge for slumber takes hold. Sleep then purges the buildup of adenosine in your brain, and you will wake feeling refreshed and ready to face another day.Today, you’ll learn about the dual-action effect of adenosine, how caffeine operates to artificially mute its “sleepiness” signals to the brain, and the ideal length of sleep you need to fully clear the adenosine levels from your body overnight. 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. Matt is more than a little obsessed with Athletic Greens. He's been using Athletic Greens, each day for the past 3 years (and he does buy his own to prevent any conflict of interest, as that's important to integrity). Why does Matt use it each day.? 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  www.athleticgreens.com/mattwalker 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 @drmattwalker.Music credit:By the incredible, Kai Engel (aka Anton Fedchenkov).

Episode 01:  HighlightsHuman sleep has been separated into two main types: Non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleepNREM sleep is further divided into four stages, with each stage increasing in their depth of sleepREM sleep is named this way because of the bizarre, horizontal, shuttling eye movements that occur underneath your eyelids during this stage of sleepREM sleep is the principal stage in which we dream, although it can occur in the other stages as wellNREM and REM sleep play out in a battle for brain domination throughout the nightThis cerebral war is going to be won and lost every 90 minutes, creating the standard cycling architecture of sleep for humansOther species may have a slightly different NREM to REM cycles, with birds experiencing a cycle that only lasts about 4-5 minutes, and giraffes about 24 minutesDuring NREM sleep, we see bursts of deeply powerful brain waves that flow over your cortexWe also see sleep spindles, which are short, synchronous bursts of electrical brain wave activity that last for about 1-1.5 secondsAbout 60-70 minutes into your first sleep cycle, your brain starts to rise up again into later stages of NREM sleep, then pop into a short REM sleep period, back to NREM sleep, then returning to REM sleep once againYour brain goes through this cycle every 90 minutesWhat changes is the ratio of NREM to REM sleep as you move through the night, with your sleep cycle comprised of more REM sleep during the second half of the nightIf you wake up two hours earlier than usual, you aren’t just losing 2 hours of sleep - you could be losing 50, 60, or even 70% of your REM sleepAll stages of sleep are critical and perform different functions for the brain and body at different times of nightEpisode Sponsor:This episode is sponsored by 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 www.athleticgreens.com/mattwalker and get a free year supply of Vitamin D and 5 free travel packs today. Feedback: Please visit Matt on Instagram and tell him what he can be doing to make these podcasts better, and let him know what topics you want him to cover next! Links:Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and StrokeMusic credit:By the incredible, Kai Engel (aka Anton Fedchenkov).