Ep209 - Sleep, Neurotransmitters & Genetics: A Precision Medicine Approach with Kendall Stewart, MD

"If I get the neurotransmitters right, your method will work better. You can be the greatest therapist in the world, and if I don't hand you a patient that's able to adapt to that therapy, you're not going to be successful."

In this episode, host Dr. Yishan welcomes Dr. Kendall Stewart — a former skull-based surgeon turned functional medicine pioneer — to explore the hidden biological roots of poor sleep. With a background in biochemistry, cell biology, and neuroimmune health, Dr. Stewart has spent over two decades using objective data and genetic testing to understand why so many people struggle to fall asleep, stay asleep, or wake feeling rested.

Dr. Stewart breaks down how neurotransmitter imbalances — from GABA and glutamate to dopamine and melatonin — can silently sabotage sleep, and how genetic variants like the GAD1 mutation, methylation deficiencies, and melatonin receptor weaknesses explain why generic advice so often fails. He shares insights from treating thousands of patients — including children on the autism spectrum — and makes a compelling case for why biological preparation is the missing piece that makes behavioral and psychological sleep therapies truly effective.

Together, Dr. Yishan and Dr. Stewart explore the frontier of nutrigenomics and precision medicine, the surprising connections between autism research and sleep science, and how accessible at-home genetic panels are beginning to democratize personalized health. If you've ever felt that sleep hygiene advice was too generic, or that your brain simply won't quiet down no matter what you try, this episode offers a brand-new lens — and real hope.

Here are 3 key takeaways you don't want to miss:

Your Genes Shape Your Sleep: Genetic variants in pathways controlling GABA production, melatonin receptor sensitivity, and dopamine methylation can all directly impair your ability to fall asleep, stay asleep, and achieve restorative sleep architecture — regardless of how good your sleep habits are.

Biology and Psychology Work Together: Behavioral sleep therapies like CBT-I and neurofeedback are significantly more effective when the brain is nutritionally and neurochemically supported. Rather than competing approaches, Dr. Stewart's functional medicine model acts as a biological foundation that makes psychological treatment land more powerfully.

Precision Over Guesswork: Not everyone needs the same supplements, and taking things you don't need wastes money and can create imbalances. Targeted genetic testing can reveal exactly which pathways are underperforming — giving you a personalized roadmap for support without the trial and error.

"Knowing what you actually need is so important. And knowing what you don't need also — because if you don't need it, you're just making expensive urine." — Dr. Kendall Stewart, MD

WHAT WILL WE LEARN

00:00 – Introduction: When sleep hygiene alone isn't enough
00:01 – Meet Dr. Kendall Stewart: From skull-based surgery to functional medicine
00:03 – The surgeon's mindset: Using objective data to see the problem
00:04 – How autism research led to nutrigenomics and genetic testing
00:05 – Parsing 10,000 genes to find 120 clinically actionable markers
00:05 – Neurotransmitter ratios: Why balance matters more than quantity
00:07 – Galanin, adenosine, and melatonin receptors: The sleep initiation puzzle
00:10 – From genetic results to real treatment: Building personalized supplement protocols
00:14 – Precision medicine: Finding what works for you, not someone else
00:17 – The 15-20 minute sleep window: Miss it and you've bought 2 more hours awake
00:19 – CBT-I and biological support: Better together
00:20 – Neurofeedback, dopamine, and why therapy outcomes depend on brain readiness
00:22 – SNRIs, natural alternatives, and reducing medication dependence
00:24 – Autism and sleep: Shared lessons from inflammation, autophagy genes, and insulin resistance
00:34 – Meditation through a neuroscience lens: Giving the brain a chance to catch up
00:37 – Rate-limiting steps: Why you can't push through a neurochemical deficit

00:43 – Final wisdom: Invest in what you know you need

Are you so sleepy that you cannot focus? Are you tired of getting through the day drinking coffee? Are you worried how your poor sleep may impact your health? Check out Dr. Yishan Xu's Insomnia Treatment Course!

Connect with Dr. Yishan

Connect with Dr. Kendall Stewart

Resources & Links

Newsletter and Free Sleep Guidance E-Book:

  • https://www.mindbodygarden.com/sleep

CBT-I Courses:

  • English: https://www.deepintosleep.co/insomnia

  • Chinese: https://www.mindbodygarden.com/shimian

Podcast Links:

  • Apple Podcast: https://podcasts.apple.com/us/podcast/deep-into-sleep/id1475295840

  • Spotify: https://open.spotify.com/show/2Vxyyj9Cswuk91OYztzcMS

  • iHeartRadio: https://www.iheart.com/podcast/269-deep-into-sleep-47827108/

  • Stitcher: https://www.stitcher.com/show/deep-into-sleep

  • Support our Podcast: https://www.buymeacoffee.com/dryishan

  • Leave us a Rating: https://podcasts.apple.com/us/podcast/deep-into-sleep/id1475295840

Yishan Xu, PhD, DBSMsleep, sleep disorder, sleep better, sleep apneaComment