#112 - How Synesthesia Secretly Shapes Your Reality

Matt explores the fascinating world of synesthesia today, challenging the notion that it's a rare quirk by proposing a bold claim: in subtle ways, we are all synesthetes. This idea is powerfully demonstrated by the famous "Bouba/Kiki" test, which reveals our brain's innate tendency to connect abstract shapes and sounds. The episode argues that this fundamental cross-wiring is not a mere curiosity but the very operating system for human thought, shaping everything from our metaphors to the development of language itself.The journey continues by exploring how these sensory perceptions can be programmed externally, as shown in a remarkable study linking synesthetes' color associations to a popular Fisher-Price toy. Matt also discusses the cognitive superpowers that can accompany synesthesia, like superior memory, and its profound connection to autism. Ultimately, the episode illuminates how everyday phrases like "feeling blue" are not just figures of speech, but echoes of the synesthetic software running in all our brains, constantly mixing senses to build our unique perception of reality.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.Craving more energy, better metabolism, and immunity? Discover Pique's Nandaka, a ceremonial cacao superfood blend for calm, sustained energy without the crash. Thanks to this wonderful podcast partner, you can now get 20% off for life at pique.com/mattwalker using code MattWalker.In a supplement industry where trust is critical, Matt uses podcast supporter Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.Podcast partner UPLIFT Desk helps Matt combat the drain of sitting all day. By making it easy to switch between sitting and standing, he stays active and focused, boosting his energy and wellbeing. You can enjoy these many benefits, too, by visiting upliftdesk.com/MATTWALKER and using code MATTWALKER for a special discount and free accessories.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

Framing sleep not as a biological necessity, but as a critical economic asset, Matt reveals that sleep deprivation costs the U.S. economy up to $411 billion annually, with billions more lost globally. These costs stem from lost workplace productivity, severe cognitive impairment equivalent to intoxication, and massive strains on healthcare and public safety systems due to chronic disease and accidents like drowsy driving.Matt provides the solution: investing in sleep as a powerful economic stimulus. Modest improvements in sleep duration could inject hundreds of billions back into the economy, with corporate sleep programs and insomnia treatments showing remarkable returns on investment. On a personal level, adequate sleep is directly linked to higher lifetime earnings and better financial decisions. The episode ultimately reframes sleep as a crucial economic investment for both personal and societal prosperity, not a sacrifice of productivity.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.As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.Another of this week's sponsors, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

In this user's guide to sleep trackers, learn the science behind how they work using motion and optical sensors as Matt explains the key metrics of Sensitivity, Specificity, and Accuracy. Revealing why most trackers overestimate sleep by failing to detect wakefulness, he reveals the crucial difference between a device's flawed "absolute accuracy" and its more valuable "relative accuracy," which highlights the importance of tracking long-term trends over single-night scores.Matt goes on to examine peer-reviewed data on the Oura Ring, Apple Watch, and Whoop, and introduces the highly accurate, FDA-cleared Happy Ring with its personalized algorithm. Beyond the specs, learn why consistency and form factor are more important than chasing perfect accuracy. The episode also covers the pitfalls of tracking, from the anxiety of "Orthosomnia" to demographic biases in sensor tech, providing a complete guide to choosing and using your device effectively.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.Podcast partner, AG1, is one that Matt relies upon for his foundational nutrition. Their new science-backed Next Gen formula features upgraded probiotics, vitamins, and minerals. Start your subscription today to get a FREE bottle of Vitamin D3+K2 and 5 free travel packs with your first order at drinkag1.com/mattwalker.Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.In a supplement industry where trust is critical, Matt uses podcast partner Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

Matt takes a deep dive into REM sleep this week, highlighting methods to enhance this vital stage for emotional regulation and creativity. Detailing pharmacological approaches, he focuses on the neurotransmitter acetylcholine and how medications like donepezil and modern DORAs can boost REM sleep, while also identifying common suppressors like alcohol and THC. Throughout the episode, he also emphasizes that the goal is not to maximize one stage but to achieve a balanced sleep architecture.The discussion then covers behavioral and lifestyle strategies, explaining how simple changes like sleeping later into the morning, regular exercise, and stress management can remove natural roadblocks to REM. Matt also outlines how managing light exposure - by avoiding blue light at night and getting bright light in the morning - and consuming complex carbohydrates in the evening can further support this dream stage. Finally, the episode touches on emerging technologies like electrical brain stimulation that aim to amplify the brain's natural REM rhythms.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 this week's sponsors, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.Our third sponsor this week, David, is a revolutionary new protein bar developed with Dr. Peter Attia. It boasts an unbeatable ratio: 28g of protein and 0g of sugar in just 150 calories. Incredibly satiating with six amazing flavors, it’s perfect for muscle health. Visit davidprotein.com/mattwalker and buy 4 cartons to get a 5th FREE!As always, if you have thoughts or feedback you’d like to share, please reach out:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

In this soothing episode, Matt guides you on your personal sleep story towards deep, restorative rest. He invites you to find comfort and release the day's worries through intentional breathing, transporting you to a cozy, imagined haven bathed in soft lights and calming aromas. As twilight descends, experience the tranquil silence and the moon's gentle glow, replacing any turmoil with profound inner peace.A powerful visualization encourages you to shed thoughts and concerns, picturing them as leaves floating away on a serene river. This practice cultivates gratitude and prepares you to let go completely. Trust that tomorrow brings new joys, and allow yourself to drift effortlessly into sleep, waking up truly refreshed and restored.Craving more energy, better metabolism, and immunity? Discover Pique's Nandaka, a ceremonial cacao superfood blend for calm, sustained energy without the crash. Thanks to this wonderful podcast partner, you can now get 20% off for life at pique.com/mattwalker using code MattWalker.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt or Eti:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

In this week’s episode, Matt Walker explores memory's astonishing malleability, challenging the belief that recollections are fixed. He highlights Loftus's car crash study, showing how subtle language altered speed memories and implanted false details, and reviews the "Lost in the Mall" experiment which proved fabricated autobiographical memories can be instilled. Matt also notes that neuroimaging reveals false and true memory patterns in the hippocampus are remarkably similar, underscoring memory's deceptive, fluid nature, rather than a factual archive.Our host goes on to discuss groundbreaking research like optogenetics from Tonegawa's lab, demonstrating manipulation to implant false fear memories at a cellular level. This underpins "memory reconsolidation" by Karim Nader, showing retrieved memories enter a "labile window" for modification. This opens profound avenues for therapies: Image Rehearsal Therapy for nightmares and propranolol for PTSD effectively weaken emotional trauma. The episode concludes by suggesting identity, objective truth, and forgiveness are dynamic, neurologically modifiable constructs, not static realities.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.Podcast partner and sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

Founder & CEO of Elevated Medical, Dr. Avinish Reddy, joins Matt today on this very special episode to discuss a comprehensive approach to longevity. One core theme presented is the profound interconnectedness of physical, mental, and cognitive well-being, essential for true health optimization. Dr. Reddy emphasizes the striking impact of social connection: isolation can increase early death risk by 50%, comparable to smoking. He believes fostering strong social bonds is a fundamental pillar of healthcare, akin to sleep's importance.The discussion highlights advanced diagnostics and actionable lifestyle strategies. Dr. Reddy advocates for precise cardiovascular risk assessment (apoB) and early metabolic dysfunction detection (fasting insulin/OGTT), with imaging (CT/CIMT) that visualizes arterial health proactively. As you will hear, prevention must begin decades before major health events, utilizing personalized data, and lifestyle is paramount - consistent movement, balanced nutrition, quality sleep, and stress management are vital for reversing conditions and fostering resilience.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.As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.Craving more energy, better metabolism, and immunity? Discover Pique's Nandaka, a ceremonial cacao superfood blend for calm, sustained energy without the crash. Thanks to this wonderful podcast partner, you can now get 20% off for life at pique.com/mattwalker using code MattWalker.In a supplement industry where trust is critical, Matt uses podcast supporter Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolgConnect with Dr. Avinish Reddy:Elevated Medical: https://elevatedmedical.com/LinkedIn: https://www.linkedin.com/in/avinishreddy/Instagram: https://www.instagram.com/avinishreddymd/

In this latest AMA instalment, Matt and Dr. Eti Ben Simon begin by discussing environmental influences on sleep. The conversation covers how high latitude and prolonged daylight disrupt circadian rhythms, with Eti sharing her own personal experience. Together, our duo shares strategies for managing light exposure and regulating core body temperature with methods like warm baths. The episode also offers evidence-based approaches for shift workers, including strategic napping and forward-rotating schedules.The discussion then shifts to internal mechanisms, debunking the "sleep before midnight" myth and emphasizing alignment with one's chronotype. The role of the thalamus as a sensory gate for blocking pain during sleep is detailed, with Eti noting that meaningful stimuli can still break through this barrier. Finally, the use of Gabapentin is examined, outlining its limited efficacy for primary insomnia versus conditions like restless legs syndrome.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.Partner of the podcast, AG1, is one sponsor that Matt relies upon for his foundational nutrition. Their new science-backed Next Gen formula features upgraded probiotics, vitamins, and minerals. Start your subscription today to get a FREE bottle of Vitamin D3+K2 and 5 free travel packs with your first order at drinkag1.com/mattwalker.Another of this week's sponsors, David, is a revolutionary new protein bar developed with Dr. Peter Attia. It boasts an unbeatable ratio: 28g of protein and 0g of sugar in just 150 calories. Incredibly satiating with six amazing flavors, it’s perfect for muscle health. Buy yours today at davidprotein.com/mattwalker and buy 4 cartons to get a 5th FREE! If they’re not already sold out, you can also find them at a local store using the store locator—or on Amazon.Our third sponsor this week, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!As always, if you have thoughts or feedback you’d like to share, please reach out:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299Eti: X @etoosh, Instagram https://www.instagram.com/eti_bensimon/,  or email at [email protected]

Matt explores the critical link between sleep and Alzheimer's disease today, explaining how the brain’s "glymphatic system" clears toxic proteins like amyloid and tau during deep sleep. He describes how insufficient sleep impairs this process, creating a vicious cycle where protein accumulation damages sleep-generating brain regions and increases dementia risk.Matt goes on to discuss groundbreaking research on a new class of sleeping pills, Dual Orexin Receptor Antagonists (DORAs), that may enhance this cleaning mechanism. While preliminary human and animal studies show these drugs can reduce toxic proteins and offer neuroprotection, the findings underscore the profound importance of prioritizing high-quality sleep as a powerful, accessible tool for ensuring long-term brain health.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 this week's sponsors, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.In a supplement industry where trust is critical, Matt uses podcast partner Puori. Their protein powders are free from hormones, GMOs, and pesticides, with every single batch third-party tested for over 200 contaminants. For protein you can trust, save 20% at puori.com/mattwalker.As always, if you have thoughts or feedback you’d like to share, please reach out to Matt:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube: https://www.youtube.com/channel/UCA3FB1fOtY4Vd8yqLaUvolg

Matt and Dr. Eti Ben Simon join forces once again to answer all of your top sleep questions. This time around, they break down the science behind the snooze button, why you might be falling asleep during passive activities like watching TV, and the truth about sleep fads like consuming salt before bed or using "grounding sheets." The episode also explores the frustrating issue of sleep fragmentation - waking up multiple times a night - and why it undermines sleep quality even if you fall back asleep quickly.Learn how to assess your own sleep quality using key daytime indicators like energy and mood, without needing a tracker. For those struggling with frequent awakenings, discover a powerful, science-backed strategy called "bedtime restructuring" to help consolidate your sleep. The episode concludes with a look at new research on a potential "fail-safe" for sleep induction linked to mitochondrial stress, revealing a new frontier in sleep science.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.As a huge supporter of mission-driven companies, Matt recommends new partner Branch Basics. Their plant- and mineral-based ‘The Concentrate’ is tough on kitchen grease yet gentle enough for baby toys, helping you create a toxin-free home. Get 15% off with code MattWalker at branchbasics.com/mattwalker.Another sponsor, Shopify, made launching Matt's merchandise incredibly smooth with its integrated sales system. Shopify simplifies everything from online stores to in-person sales. Start your exclusive trial and see for yourself at shopify.com/mattwalker.A third sponsor this week, LMNT, offers a science-based electrolyte drink with no sugar or artificial ingredients. Try their new limited-time Lemonade Salt flavor, available May 20th! Get eight free sample packs with any order at drinklmnt.com/mattwalker. Stock up on this summer flavor while it lasts!As always, if you have thoughts or feedback you’d like to share, please reach out to Matt or Eti:Matt: Instagram @drmattwalker, X @sleepdiplomat, YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299Eti: X @etoosh, Instagram https://www.instagram.com/eti_bensimon/,  or email at [email protected]