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