Most people think melatonin is only about sleep. That’s the mistake. In reality, some of the highest concentrations of melatonin in the body are found in the gut, where it helps protect the intestinal barrier, regulate immune responses, reduce oxidative stress, and prevent the kind of chronic inflammatory “leak” that drives fatigue, brain fog, poor recovery, and ongoing post-COVID symptoms.
In this free Masterclass session, I break down why melatonin is far more important than most people realise—especially in a post-pandemic world where gut dysfunction and immune overactivation are becoming increasingly common. This is how I approach health inside the McMillan Masterclass series: not by chasing symptoms, but by identifying the ROOT cause and understanding the physiology behind why the body is struggling.
I wanted to make this session available as a free taster because it shows exactly how these masterclasses work. If this way of thinking resonates with you, you can join the full Masterclass Membership for access to the full on-demand library or the live sessions where we work through these principles together in real time.
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In this important session, Dr. McMillan reframes melatonin as far more than a sleep hormone. While most people associate it with the pineal gland and circadian rhythm, he explains that the gut contains some of the highest concentrations of melatonin in the body, where it acts as a local immune regulator and mucosal protector.
The central theme is that melatonin helps stabilize the intestinal barrier, protect mitochondrial function, and reduce oxidative stress within the gut lining. When levels fall—through aging, poor sleep, chronic stress, dysbiosis, alcohol excess, shift work, or reduced tryptophan absorption after COVID—the intestinal barrier becomes more permeable. This allows bacterial toxins and metabolites to cross into the bloodstream, driving systemic immune activation and ongoing inflammation.
The key principle: protect the gut barrier first. Melatonin can support the rebuilding phase, but it should be used as part of a broader sequence that includes sleep optimization, gut repair nutrients, and restoration of microbiome health rather than as a standalone solution.
🔹 Questions Asked After the Presentation
Is melatonin only important for sleep?
→ No. It also acts locally within the gut to regulate immune signaling and protect the mucosal barrier.Why is the ileum particularly important in this discussion?
→ The ileum contains major immune-sensing regions such as Peyer’s patches, making it central to gut immune responses.Who is most likely to have low gut melatonin?
→ Shift workers, older adults, people under chronic stress, those with poor diet, alcohol excess, dysbiosis, or inflammatory bowel conditions.Can melatonin supplements help repair the gut?
→ Potentially, especially during the rebuilding phase, but lifestyle strategies and gut repair sequencing should come first.What dose of melatonin is typically used?
→ Lower doses (0.3–1 mg) are generally used to mimic natural physiology, while higher doses may be considered short term for gut inflammation support.How long should melatonin be used?
→ Usually short-term, often a few days to help reset sleep and support gut repair, rather than as a long-term dependency.What else should be used alongside melatonin for gut repair?
→ Zinc carnosine, L-glutamine, butyrate, omega-3s, vitamin D, selenium, and magnesium were discussed as part of the repair phase.Can gut inflammation worsen joint pain?
→ Yes. Ongoing gut-driven immune activation can amplify inflammatory signaling in joints and worsen arthritis-type symptoms.
