This week, Matt dismantles the myth that REM sleep only benefits the mind by revealing its profound importance for physical health. While deep sleep handles some repair, Matt details how REM is crucial for peak testosterone and growth hormone release, vital for muscle, bone, libido, tissue repair, and metabolism. He explains that REM's characteristic muscle paralysis (atonia) isn't just for safety; it fosters physical recovery by enabling deep muscle relaxation, boosting blood flow, lowering cortisol, and regulating inflammatory cytokines.

Matt further explores how REM resets the body's thermostat, enhances cardiovascular health through heart rate variability, and improves lung function via unique breathing patterns. This vital stage also supports genital tissue health, significantly ramps up protein synthesis for muscle repair, and strengthens the immune system by promoting essential cells and cytokines. Matt concludes that protecting REM sleep is non-negotiable, as it serves as a cornerstone for both mental and essential physical restoration and function.

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.

Matt will be the first to tell you that launching his sleep-related merchandise sales was incredibly smooth, thanks to our new sponsor Shopify and their integrated sales and inventory system. And now, just for you, Shopify is generously offering an exclusive trial at shopify.com/mattwalker. Whether it's online or in-person sales, Shopify simplifies it all. So, be sure to stop in at shopify.com/mattwalker to start your exclusive journey now!

Another of our sponsors this week 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 get behind - 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. 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.

Tired of untrustworthy protein shakes? Show sponsor Puori prioritizes quality: hormone-free, GMO-free, and pesticide-free. Every batch is third-party tested for 200+ contaminants - you can even scan the QR code for lab results! Matt recommends the addictive dark chocolate flavor with 21g of protein. Ready to experience the Puori difference? Matt’s listeners get 20% off, so visit puori.com/mattwalker today!

As always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.

Matt: Instagram @drmattwalker or on X @sleepdiplomat

YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

In this latest AMA episode, Matt and Dr. Eti Ben Simon tackle even more listener questions regarding any and all aspects of sleep. Today, they discuss sleep tracker accuracy, noting that while nightly data isn't perfect (~75-85% accurate), weekly trends are reliable. Feeling exhausted despite good tracker metrics? Potential causes include fragmented sleep, circadian issues, undiagnosed disorders (like apnea), or tracker-induced anxiety (orthosomnia). Matt and Eti stress consulting a specialist for persistent fatigue and focusing on long-term data patterns.

They also explore why many wake around 3:30 AM, linking it to shifts into lighter sleep stages and hormonal changes (cortisol rise, melatonin drop). The hosts explain alpha wave intrusion's link to nonrestorative sleep, theories behind teeth-falling-out dreams (trigeminal nerve activity), and differing sleep onset times (partner variations, potential sleep debt). They also touch upon how antidepressants affect dream recall via REM sleep reduction and debunk precognitive dreams, attributing them to statistics and cognitive bias, not prophecy.

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.

Matt will be the first to tell you that launching his sleep-related merchandise sales was incredibly smooth, thanks to our new sponsor Shopify and their integrated sales and inventory system. And now, just for you, Shopify is generously offering an exclusive trial at shopify.com/mattwalker. Whether it's online or in-person sales, Shopify simplifies it all. So, be sure to stop in at shopify.com/mattwalker to start your exclusive journey now!

Another great sponsor of the show is AG1, a comprehensive nutritional drink trusted by thousands worldwide, including Matt! For nearly four years and counting, he has relied on AG1 to fuel his post-workout routine with its powerhouse blend of over 75 essential minerals, vitamins, probiotics, and prebiotics, meticulously crafted to support your daily nutritional needs. AG1 is registered and approved by the Therapeutic Goods Administration, boasting GMP badges for quality assurance. As a special offer for our listeners, when you try AG1, you'll receive a complimentary one-year supply of both Vitamin D and K2, and with your first subscription, you'll also receive five free AG1 travel packs! Visit AG1 to explore AG1's range of offerings and claim your exclusive offer.

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

Eti: X @etoosh, Instagram https://www.instagram.com/eti_bensimon/, or email at etoosh@gmail.com

Dr. Cheri Mah returns to the podcast today to explore a few different topics including how circadian rhythms shape athletic performance. She notes that these 24-hour cycles regulate sleep, hormones, and core temperature, with peak physical capacity often occurring between 4-8 pm—when many world records are set.

Dr. Mah also discusses chronotypes, showing how tailoring training to one’s natural rhythm can enhance results. She reveals research on circadian disruption in sports, notably how West Coast NFL teams outperform East Coast teams in night games due to a three-hour body clock advantage. The episode also covers jet lag strategies, sleep loading, and managing fatigue, making it a must-listen not just for athletes and high performers, but truly for us all.

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.

Matt is only too happy to share the fact that launching his sleep-related merchandise sales was incredibly smooth, thanks to show sponsor Shopify and their integrated sales and inventory system. And now, just for you, Shopify is generously offering an exclusive trial at shopify.com/mattwalker. Whether it's online or in-person sales, Shopify simplifies it all. So, be sure to stop in at shopify.com/mattwalker to start your exclusive journey now!

One of our sponsors this week 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 get behind - 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. 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 great sponsor of the show is AG1, a comprehensive nutritional drink trusted by thousands worldwide, including Matt! For nearly four years and counting, he has relied on AG1 to fuel his post-workout routine with its powerhouse blend of over 75 essential minerals, vitamins, probiotics, and prebiotics, meticulously crafted to support your daily nutritional needs. AG1 is registered and approved by the Therapeutic Goods Administration, boasting GMP badges for quality assurance. As a special offer for our listeners, when you try AG1, you'll receive a complimentary one-year supply of both Vitamin D and K2, and with your first subscription, you'll also receive five free AG1 travel packs! Visit AG1 to explore AG1's range of offerings and claim your exclusive offer.

Matt: Instagram @drmattwalker or on X @sleepdiplomat

YouTube https://www.youtube.com/@sleepdiplomatmattwalker9299

Connect with Dr. Mah: https://www.drcherimah.com/ or https://linktr.ee/drcherimah

Caffeine Nap Episode: https://podcasts.apple.com/us/podcast/58-caffeine-nap/id1578319619?i=1000630666364

Chronotype Assessment: AutoMEQ: Automated Morningness-Eveningness Questionnaire (AutoMEQ)