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Hey everybody, Mikki here. You're listening to Mini Mikkipedia on a Monday. And today I want to talk about something that came up from a question in my community. And it is on a topic that will resonate with a lot of you. A member of my community asked about cortisol, specifically about the combination of exercise, work stress, scattered energy, poor sleep, and a persistently elevated morning heart rate.

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and whether any of it is normal and what she needs to do about it. And my answer to the first part is that it's not normal, but it is common, but common also doesn't mean inevitable. And it's not something you just have to accept as the price of being a busy driven person, as I know many of you are. So today I wanna unpack what actually is going on physiologically, why the modern version of the stress picture is so insidious.

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and what the evidence actually supports in terms of bringing your system back into balance. So let's start with the hormone itself, cortisol, because it has become something of this wellness villain, if you like. And I do think that framing it in that way does more harm than good. So cortisol is a glucocorticoid hormone produced by the adrenal glands, and it's absolutely essential to your survival.

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It follows a natural diurnal rhythm. It peaks sharply in the first 30 to 45 minutes after awakening. This is called the cortisol awakening response. And then gradually tapers across the day, reaching its lowest point in the late evening. That morning spike is what gets you out of bed, mobilizes glucose and fatty acids for fuel, ramps up alertness and focus, and primes the immune system for the demands ahead. It's not something going wrong. It's your body doing exactly what it should. Exercise-induced cortisol is the same story.

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When you train cortisol rises as part of the acute stress response. It's coordinating the release of energy substrates, managing inflammation and signaling the body to adapt. That response is what drives fitness gains. The stress and subsequent recovery, the resolution of that stress, is what makes you more resilient over time. And if you never stress the system, you'd never adapt. So exercise-induced cortisol is genuinely a feature and not a bug.

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And what I would also say is that the stress of exercise making you more resilient in the session or four subsequent sessions is also making you more resilient in life overall. When you're able to adapt, resolve and become more resilient through exercise, you're actually able to handle stress from other areas so much more efficiently and effectively. Work stress though, social pressure, a looming deadline, it uses that same pathway.

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cortisol rises, you get focused and ready to act, you perform, again that cortisol diminishes and it's resolved. This isn't inherently a problem. But the problem is when cortisol never fully comes back down. So to understand why chronic stress is so damaging, it helps know a little of the system that regulates cortisol, the hypothalamic pituitary adrenal axis or HPA axis. Here's how it works. When your brain perceives a stressor,

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whether that's a physical threat, an emotional trigger, sleepless night, or even just a stressful thought, the hypothalamus releases corticotropin-releasing hormone, or CRH. That signals the pituitary to release adrenocorticotropin hormone, ACTH, which then travels via the bloodstream to the adrenal glands and prompts that cortisol release.

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There's also a negative feedback loop built in. When cortisol levels are high enough, the hypothalamus and pituitary get the signal to back off. And that's how, in a healthy system, the response is self-limiting. But when the stressors are chronic and unrelenting, relentless work demands, financial pressure, poor sleep, caregiving load, or even that persistent low-level hum of anxiety, the system never gets the signal to stand down. Feedback loop becomes dysregulated.

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cortisol either remains chronically elevated or in some cases of long-term chronic stress, the system can actually become blunted. Where cortisol output is paradoxically low because the HPA axis has essentially become non-responsive. At both ends of this dysregulation, there is a problem. The downstream consequences are significant,

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Chronically elevated cortisol suppresses your immune system, so it's actually immunosuppressive at high sustained levels, which is why people under chronic stress get sick more often. It disrupts sleep architecture, particularly suppressing that deep, slow wave sleep, which is when physical recovery and memory consolidation happen. It impairs glucose regulation, promoting insulin resistance over time, and it increases that central adiposity, that cortisol-driven fat storage, visceral fat,

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tends to preferentially accumulate around the abdomen. It affects mood and cognitive function, particularly working memory and emotional regulation, and it suppresses reproductive hormone production. And one of the first things to go offline when the body is under sustained stress is that hypothalamus pituitary gonadal axis, the one that governs estrogen and progesterone in women. So when someone says they feel wired but tired, scattered, can't shift body fat,

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sleep is light and unrefreshing and their motivation is low, this is the physiology underlying that experience. And what about the morning heart rate piece? So that's worth chatting about too, because it's actually a really useful window into your autonomic nervous system state. Your heart rate is governed by the balance between your sympathetic nervous system, fight or flight, more than that, but for the purposes of this, and your parasympathetic nervous system, your rest and digest. In a well-recovered, well-rested individual,

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Morning resting heart rate should be low. And we're talking sort of 50s to 70s for most people, potentially lower for well-trained athletes. The parasympathetic nervous system should be dominant when you're horizontal before the demands of the day kick in. So when morning heart rate is consistently sitting in the high 90s or above 100, it tells you that that sympathetic nervous system is running hot even at rest. The body is in this low grade state of activation like a car engine that never fully idles down.

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Heart rate variability or HRV is the flip side of this. When HRV is low, means that autonomic nervous system is rigid and sympathetically dominated with less capacity to flex and respond. Both elevated resting heart rate and low HRV are markers of insufficient recovery and excess physiological stress load. And it's important to note that the stressor doesn't need to be physical. Psychological and emotional stress, anxiety, unresolved conflict,

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mental load, anticipatory worry, activates the same sympathetic pathways as physical stresses. So your nervous system doesn't discriminate between a lion and a looming inbox. The response is the same. And despite the fact that we are no longer living in caves, having to worry about where our next meal is coming from, or having to fight for that meal, our nervous system blueprint is exactly the same. And we'll also say you don't need a device to tell you any of this.

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you probably already know it. And my member asked whether I thought an Aura Ring or an Apple Watch would be good for her to track her sleep data or to measure her morning heart rate more accurately. I mean, monitoring can be genuinely useful for seeing patterns over time, but she was clearly already clued into what was going on because she could tell what her morning heart rate was doing. And for people who are already anxious and stressed, daily granular data on sleep scores, HRV,

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and readiness can create its own anxiety loop and that anxiety itself becomes a stressor. And look, I I have also over the last 12 weeks really seen things that my Garmin tells me that can create a little bit of a stress response in me. Like I'm now unproductive in almost every session and or overreaching. My VO2 max has dropped like three points and reading that just after like a uh training session, it's an overly

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helpful actually so I think a deeper dive for some people just may provide more stress than just not knowing that information on paper. And there is actually a term for this it's called orthosomnia which was coined to describe the preoccupation with achieving perfect sleep data and paradoxically makes sleep worse and I think the same principle extends to stress monitoring. Checking your readiness score is making you more anxious the tool is working against you.

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And I mean, look, the goal isn't to obsessively monitor your stress, obviously. It's to do things that actually reduce it. Use the data as a general trend, not a daily verdict. And if it is causing you more anxiety than insight, then I definitely think you need to take a break from it. So what we have to do here isn't necessarily to shift up training, although we'll talk about that. It's not to make massive dietary shifts, particularly for this member who is already following.

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a lot of what I advocate with regards to diet, like she's following those main pillars, but it's about helping resolve that nervous system response. That stress response evolved to be short-lived, but modern life has essentially removed the resolution part. And so we have to create it deliberately, like this will not happen by accident. So, breath work is probably the fastest and most accessible nervous system down regulation tool we have.

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The reason it works is that breathing is one of the only autonomic functions that we consciously control, and that exhalation phase is specifically linked to your parasympathetic activation. When you extend your exhale relative to your inhale, you're directly stimulating the vagus nerve, which is the main driver of parasympathetic tone. Try a four count inhale through your nose and a six to eight count exhale through the mouth or nose.

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Even five minutes of this can measurably shift heart rate and HRV in the direction of recovery. Box breathing, which is four counts in, hold, four out, and hold, is another option that works well for people who find extended exhales difficult initially. And the key is consistency, doing this daily, not just in moments of crisis. This is what will shift your baseline over time. And there's also substantial body of research on what the Japanese call shinrin-yoku.

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Forest bathing. And the physiological effects are genuinely impressive. So studies show that even short periods in unnatural environments produce measurable reductions in salivary cortisol, blood pressure, heart rate, and sympathetic nervous system activity, alongside increases in sympathetic activity and natural killer cell function, which is this innate part of our immune system. So you don't need a forest, a park, time near water. It's not just green space, it's blue space as well.

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Even barefoot on your grass has documented effects. The mechanisms are thought to involve phytoncides, which are volatile organic compounds released by plants, as well as the multi-sensory engagement of being in a non-threatening, non-demanding environment. Interestingly, even viewing images or videos of nature produces some of these effects, though the real thing is substantially more potent. And there is, in evolutionary biology, a thought that it's because as humans,

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Our modern day environment is very foreign to our DNA. You know, we've clearly been living in houses in this urban environment for hundreds of years, but not thousands, not millions. And our genetic blueprint thrives in this natural environment, which is thought to be at the foundation of the impact of this time in nature. So if you are in an urban environment, like most of us, even a few photos of a forest or beach as a screensaver,

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That's not nothing, but getting outside is clearly preferable. Meditation and mindfulness. So the evidence base for this is now substantial and it's well replicated. So regular practice, even 10 to 20 minutes daily has been shown to reduce cortisol levels, improve HRV, reduce the amygdala reactivity, and that's the brain's threat detection center, and increase prefrontal cortical activity, which is associated with that emotional regulation.

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The mechanism is essentially repeated practice at redirecting attention away from that threat-based thinking and returning the nervous system to the present moment. Over time, this builds those structural changes in the brain. Prefrontal cortex thickens with meditation practice, and the amygdala can actually shrink. Prayer functions through overlapping mechanisms for those for whom it's meaningful. The experience of surrender, connection, and trust is physiologically calming regardless of that theological framework.

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The member of my community that submitted this question was already doing this, which is wonderful, right? And consistency matters far more than duration. Daily five minutes will do more for your baseline than an hour once a week. And journaling and expressive writing does have more science behind it than most people realize. There's research by James Pennebaker at the University of Texas showed that expressive writing about stressful or emotional experiences, 15 to 20 minutes a few times a week,

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produce significant improvements in immune function, mood, and even health outcomes in clinical populations. The proposed mechanism is that unprocessed stress sits in what is sometimes called this open loop. The brain keeps returning to it, trying to resolve it, maintains this low-level activation state. And I think almost all of us know what that feels like, or at least, I mean, I certainly do. Writing externalizes the loop and allows the brain to perceive the situation as processed.

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which reduces that ruminative activation. It doesn't need to be structured or it doesn't need to be written well, whatever that means. A stream of consciousness, whatever is on your mind is often more effective than curated entries and narratives. If there's a specific source of stress, a relationship, a work situation, a fear, writing about it specifically, including your emotions and your perspective, tends to be more useful than general gratitude journaling.

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though gratitude practice has its own documented benefits for mood and wellbeing. Sometimes what's running the stress response actually isn't a current situation or stressor. So that's important to acknowledge. It may be older, unresolved material that's stored in the nervous system itself. And this is where lifestyle tools have limits and we're working with a skilled therapist becomes genuinely important. So somatic therapies, approaches like somatic experiencing, NMDR or sensory motor,

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psychotherapy, work directly with the body's held stress patterns rather than just cognitive reframing. The premise is that traumatic or chronically stressful experiences can become encoded in the body as patterns of activation, tension, or shutdown, and that talking alone doesn't fully discharge them. These approaches have really good evidence behind them, particularly for anxiety, trauma, and chronic stress presentations.

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So if the scattered weird feeling has been present for a long time and feels bigger than current circumstances would explain, then this definitely is worth exploring. Now, hydration is one of the most overlooked contributors to elevated cortisol, or dehydration if you like, and heart rate. And I really want to chat about that too. Even mild dehydration, 1 to 2 % of body weight, has been shown to elevate cortisol, increase heart rate, and impair cognitive performance.

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The mechanism is partly cardiovascular, so when blood volume drops with dehydration, the heart has to work harder to maintain that cardiac output. And that drives heart rate up and activates that sympathetic pathway. For active people who sweat regularly, dehydration is an easy chronic state to slip into, especially if you're not replacing sodium alongside fluids. Sodium is that primary electrolyte that holds water in that extracellular space.

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Drinking plain water without adequate sodium can fail to rehydrate at that cellular level if electrolyte balance is off. So start your morning with a large glass of water with a small pinch of salt or an electrolyte supplement before coffee or food. And coffee can amplify cortisol, particularly if you're not a habitual drinker or if you are sensitive to caffeine. So getting fluid and salt in first helps with that better foundation. And of course movement

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as medicine is so important, but you need to match the dose to your state. So exercise is one of the most powerful tools we have for long-term stress resiliency. It reduces baseline cortisol over time, improves HRV, promotes better sleep, and directly reduces anxiety through the release of endorphins and BDNF, brain-derived nootropic factor, which is essentially fertilizer for the brain. But the dose does matter, and this is where a lot of driven health-conscious people

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can go wrong. When the system is already under high physiological stress load, like poor sleep, high life stress, chronically elevated cortisol, adding intense training on top of it can push that HPA excess further into dysregulation rather than restoring it. The body cannot distinguish between cortisol from hard interval session and the cortisol from a terrible night's sleep and a difficult day at work. It all accumulates. If your morning heart rate is elevated, your sleep is poor.

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And you're feeling wired and depleted? That's a signal to reduce training intensity temporarily. Not abandon exercise, but swap out some of those high intensity sessions for walking, yoga, easy cycling and swimming. These lower intensity modalities are actively parasympathetic promoting and restorative, not just neutral. Once your baseline stabilizes, you can build intensity back in. And this isn't a permanent state. It's about reading the current context accurately and acting accordingly, right?

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So what I want oh you to take away from this is that your psychological state has a physiological-based solution because the psychology and physiology are all intermingled. Your nervous system is asking for a resolution and for the completion of that stress cycle that modern life keeps interrupting. So it needs inputs that signal safety, like slow breaths, time in green spaces, stillness, connection, rest.

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adequate fuel and fluid. These are basically biological requirements for a system that's been running in overdrive. The morning heart rate and that sleep quality, the mood and energy, all of these will improve as the downstream effects of these changes. So focus on shifting the conditions and the markers will follow. And if you're already doing some of these things and it still feels hard, be patient with yourself and consider whether

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professional support might be the missing piece. There's no shame in that. Sometimes the load is just genuinely large. Having skilled support makes an enormous difference. All right, team, hopefully this resonated with you and there was some practical take homes that if you recognize yourself in any of these symptoms, you'll be able to use. Let me know. I'm over on Instagram, threads and X @mikkiwilliden Facebook @mikkiwilliden in nutrition, or head to my website, @mikkiwilliden.com.

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Scroll all the way down to the bottom, pop your name into the box, and jump on my weekly email list where I talk about all things like this and more on a weekly basis. All right guys, you have the best week. See you later.