While we often think of sleep and diet as separate pillars of health, our internal biological clocks and gut microbiome intricately connect them both. In this episode, co-hosts Dr. Siobhan McCormack and Dr. Sheena Fraser dive into the fascinating, bidirectional relationship between circadian rhythms, sleep quality, and gut health.They discuss how our physiology adapts to 24-hour light and dark cycles, the metabolic havoc caused by social jet lag and shift work, and how our gut microbes actually operate on their own daily schedules. Plus, Siobhan and Sheena share practical, evidence-based chrononutrition strategies and explore how targeted dietary patterns, probiotics, and fermented foods can significantly boost your mood and sleep architecture.What We Cover:The Circadian Symphony: How light, dark, and our body's internal peripheral clocks orchestrate everything from hormone release (like cortisol and melatonin) to digestion.Sleep Architecture & Mental Health: The critical role of REM and deep sleep, and how just one night of sleep deprivation increases impulsivity and degrades mood.Chrononutrition: Why when you eat is just as important as what you eat, and how meal timing acts as a major environmental cue for your gut microbes.Social Jet Lag & Shift Work: The metabolic consequences of disrupted sleep cycles, including increased risks for Type 2 Diabetes, and actionable strategies to regain circadian balance.Nutrients & Microbes for Sleep: Exploring the science behind specific dietary protocols, the power of Lactobacillus, and how fermented foods support restorative rest.Scientific References & Further Reading:Conti, F. (2025). ‘Dietary protocols to promote and improve restful sleep: A narrative review’. Nutrition ReviewsDobielska, M. et al. (2025). ‘Association between fermented food consumption and sleep quality under psychological stress: Prospective cohort study’. Food Science & Nutrition.Scott, A.J., Webb, T.L., Martyn-St James, M., Rowse, G., & Weich, S. (2021). 'Improving sleep quality leads to better mental health: A meta-analysis of randomised controlled trials'. Sleep Medicine ReviewsHepsomali, P., & Groeger, J.A. (2021). 'Diet, sleep and mental health: Insights from the Uk Biobank Study'. NutrientsReid, M., Omlin, X., Espie, C., Sharman, R., Tamm, S., & Kyle, S. (2022). 'The effect of sleep continuity disruption on multimodal emotion processing and regulation'. Journal of Sleep ResearchMarx, W., Manger, S.H., et al. (2023). 'Clinical guidelines for the use of lifestyle-based mental health care in major depressive disorder'. World Journal of Biological PsychiatryVetter, C. et al. (2018). 'Night Shift Work, Genetic Risk, and Type 2 Diabetes in the UK Biobank'. Diabetes CareThis podcast is brought to you in collaboration with the British Society of Lifestyle Medicine.Disclaimer:The content in this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or qualified healthcare provider. Never disregard professional medical advice or delay in seeking it because of something you have heard on this podcast.

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