The sleep habit that quietly raises your risk of heart disease | Dr Kristen Knutson

In this episode, I’m joined by Dr Kristen Knutson to unpack circadian health and how timing influences our metabolism, cardiovascular health, and sleep quality. We discuss the role of morning light, meal timing, exercise, and regularity, and why modern lifestyles often push our biology out of sync. Dr Knutson also clarifies common misconceptions about melatonin, wearable sleep trackers, and what to do if you wake up in the middle of the night and struggle to fall back asleep. What We Cover What circadian health is and how disruption occurs in everyday life Why morning light is the strongest signal for your internal clock Meal timing basics, including why avoiding food close to bedtime matters Exercise timing and the simple rule most people should follow Sleep health beyond hours slept: quality, timing, and regularity Practical strategies for waking during the night and falling back asleep Understanding circadian rhythms can help you make small changes that support better sleep, better energy, and long-term health. To connect with the guest, follow Dr Kristen Knutson on LinkedIn and explore her research profile via Northwestern Feinberg. Intro (00:00) America’s 24/7 Problem (02:48) Night Owls: Is Your Sleep Schedule Genetic? (14:04) Why "Catching Up" on Sleep Fails (20:00) How to Use Light & Melatonin (29:16) Meal Timing and Weight Gain (37:27 The Best Fasting Window for Your Circadian Rhythm (43:25) Can Late Workouts Ruin Sleep? (48:07) Deep Sleep vs. REM (55:23) How Your Brain Fights to Recover (58:32) Hacks for Falling Back To Sleep Quickly (01:03:27) The Holy Trinity of Health: Diet, Exercise, and Sleep (01:12:00) One Simple Step to Start Today (01:15:56) This episode is brought to you by: 38TERA Consider 38TERA's DMN prebiotic supplement a daily multivitamin for your gut. Formulated by yours truly and gastroenterologist Dr Will Bulsiewicz. Use code THEPROOF for a discount at checkout. 38Tera ships to the United States, Australia, and New Zealand. Mill Mill is an odourless, fully automated food recycler that turns kitchen scraps into clean, dry grounds overnight with no smells or mess. Get $75 off and try it risk-free for 90 days at mill.com using code THEPROOF. Mill ships within the United States. Function Health Take charge of your health with advanced blood testing and personalised insights. Function Health offers a practical way to track key health markers such as cholesterol, blood sugar, and more. Learn more and join at functionhealth.com/simonhill for a $25 credit toward your membership. Only available to those living in the United States. Function Health ships to 48 U.S. states, excluding Rhode Island, Hawai‘i, and Puerto Rico. Shopify Shopify, the world's leading e-commerce platform, helps you turn browsers into buyers with the internet’s best-converting check out–up to 36% better compared to other leading e-commerce platforms. To boost your conversion rate, and grow your business, sign up for your one-dollar-per-month trial at shopify.com/proof. WHOOP Whoop, the most advanced fitness and health wearable available. Your personalised fitness and health coach to recover faster, sleep better, and train smarter. Claim your first month free on join.whoop.com/simon. Whoop ships to 56+ international markets, including the US, Canada, most of Europe, Australia, New Zealand, UAE, Singapore, and parts of Asia. Simon Hill, MSc, BSc (Hons) Creator of theproof.com Host of The Proof with Simon Hill Author of The Proof is in the Plants Subscribe & Connect: YouTube Apple Podcasts Spotify Instagram: @simonhill Twitter: @theproof Facebook: The Proof with Simon Hill