Creatine, Sleep and Iron: Three Overlooked Pillars of Health You're Probably Getting Wrong
Some of the most powerful levers for health aren't exotic biohacks, they're basic, well-studied and often misunderstood. In a recent Innersight Podcast Special, we tackled three of them back to back: creatine, sleep and iron. Each one, it turns out, is quietly foundational to how well your body actually performs and recovers, and each one comes with a set of myths that keep people from getting the benefit.
Part One: Creatine Isn't Just for Bodybuilders
Creatine has one of the strangest reputations in supplement science: more than 30 years on the market, north of 600 published studies, and still widely misunderstood as something only bodybuilders need. The current scientific consensus is considerably broader: most people, from adolescents to the elderly, could benefit from taking it.
What creatine actually does
Creatine is a compound - not a protein, not a peptide, made from three amino acids (arginine, glycine and methionine). Your body produces roughly half of what it can actually store; the rest comes from diet, primarily meat and fish, or supplementation.
A simple way to think about it: your body has multiple energy systems, roughly like building a fire. Creatine is the match: it fuels the first explosive 10 seconds of intense effort (a sprint, a heavy lift, a sudden reactive movement). It works by donating a phosphate group to ADP, regenerating it into ATP, the body's core energy currency, for that immediate burst. Glycolysis (breaking down glucose) is the firelighter that kicks in next, followed by the Krebs cycle for longer, sustained effort, and finally fat oxidation for endurance activity. Protein, by contrast, isn't really part of this energy-production chain at all.
This is why creatine has such an outsized effect on fast, powerful movement, but its benefits extend well beyond athletic performance.
Who actually benefits:
Athletes and strength trainers - the classic use case, supporting fast-twitch muscle fibers and explosive output.
Older adults - that same fast burst of ATP availability supports the quick reactive movements involved in, say, catching yourself after a misstep, which matters enormously for fall prevention.
Adolescents in contact sports - creatine appears to support brain function and has shown promise in the context of traumatic brain injury protection. The point was made strongly enough that some researchers argue discouraging creatine use in contact-sport athletes could itself be considered giving harmful advice.
Perimenopausal and menopausal women - creatine may help support bone density as estrogen declines, by stimulating osteoblast activity (the bone-building cells). This slots in alongside two other recurring themes from the podcast - estrogen support and iron status - as a trio worth paying attention to during this life stage.
Cognitive health in general - studies suggest creatine can support cognition, particularly under conditions of mental fatigue or sleep deprivation, and may help delay onset of dementia-related cognitive decline.
One notable distinction: the muscular and skeletal benefits of creatine require you to actually train and place demand on the tissue to see results. The cognitive/brain benefits, by contrast, appear largely independent of exercise.
Clearing up the myths:
"It makes you bloated."
This largely stems from older, high-dose loading protocols (some athletes historically loaded with 30g/day - several times more than needed). Modern guidance skips loading altogether, using a smaller, steady daily dose until stores are saturated. Any water retention that does occur is intracellular - inside the muscle cell, supporting a more anabolic environment, not the kind of puffy water retention people fear.
"It's bad for your kidneys."
A major position statement from the International Society of Sports Nutrition (published February 2025) reinforced that there's no clinical evidence of harm to kidney function. The confusion arises because creatine's breakdown product, creatinine, is one of the standard markers doctors use to assess kidney function - so supplementing with creatine will raise creatinine slightly, but this reflects supply, not kidney damage. It's worth mentioning to your doctor if you're being tested, simply so the result is interpreted correctly.
"It causes cramps."
Again, largely tied to old high-dose loading protocols. At sensible, steady doses, this isn't typically an issue.
The bottom line: most households should probably have a tub of creatine in the cupboard.
Click here to read more: Creatine Supplementation - Press Release from the International Society of Sports Nutrition
Part Two: Sleep - The Superpower Most People Are Getting Wrong
Sleep specialist Dr. Karjieker joined us to unpack why so many people quietly live with sleep problems without ever realizing it, and how that quietly undermines everything else in a health optimization plan.
There's no single "normal"
How much sleep someone needs varies significantly between individuals - some people function well on 4 hours, others need 7 or more. Rather than fixating on a specific number, the more useful marker is simple: do you wake up refreshed? If not, something is off, whether it's sleep timing, sleep quality or an underlying issue like obstructive sleep apnea.
Strikingly, a large number of people live with sleep issues for years without recognizing them as abnormal: waking to urinate repeatedly, waking up tired, or simply assuming persistent fatigue is just "life" or stress.
The scale of the problem
Up to 20% of the population snores heavily, and between 5-9% have significant obstructive sleep apnea - a proportion that carries real consequences, particularly for professions like truck driving where impaired alertness becomes a public safety issue. Left unaddressed, sleep-disordered breathing has been linked to downstream conditions including hypertension, arrhythmias and diabetes.
Two golden diagnostic questions
Dr. Karjieker highlighted two deceptively simple screening questions that flag more than 60% of patients with an underlying issue:
Do you wake up with a dry mouth? This points to mouth breathing during sleep, which is never supposed to happen. Nose breathing (during both sleep and exercise) filters, warms and humidifies air, supports better oxygenation, and increases nitric oxide production. Mouth breathing, by contrast, tends to produce shorter, shallower breaths.
Do you wake up to urinate and are you male? For most men without a prostate issue, this shouldn't be a regular occurrence. It's often overlooked as a "urology" problem when it's actually a sleep-disordered breathing symptom, tied to excess fluid intake, alcohol or caffeine before bed.
Simple, high-leverage sleep hygiene fixes
Cut caffeine by early afternoon. Caffeine remains active in the body for 6-8 hours and can both delay sleep onset and cause middle-of-the-night waking (commonly around 2 a.m.). This includes green tea and strongly steeped tea, both of which carry meaningful caffeine content; rooibos and chamomile are safer evening alternatives.
Avoid intense exercise after 7 p.m. It can leave you too physiologically "wired" to fall asleep easily.
Review medication timing. Some statins can cause insomnia when taken at night; switching timing or medication (in consultation with your doctor) can resolve sleep issues without needing a sleeping tablet at all.
Treat sleeping tablets as a last resort, not a first response, particularly for younger adults. Addressing the underlying cause (caffeine, exercise timing, obstruction, medication) is preferable to defaulting to medication, which is often prescribed too readily when a patient simply reports "not sleeping well."
Part Three: Iron Deficiency - The Blind Spot Even Among Elite Athletes
The conversation then turned to iron, described as the most common nutritional deficiency in the world, and one that's persistently under-recognized, even among doctors and elite athletes. Dr. Claire Barrett joined us in this discussion to help shed more light on this subject.
Why standard screening misses it
Several common practices delay diagnosis significantly:
Waiting for hemoglobin to drop. By the time hemoglobin is low, iron deficiency has typically been present for a long time - iron plays roles in the body far beyond hemoglobin production alone.
Waiting for MCV (red blood cell size) to fall. Relying on this "morphologic" approach again catches the problem only once it's severe.
Trusting lab flags alone. Reference ranges vary between labs and are often not flagged as abnormal even when a result, say, a ferritin of 21 is well below what's considered optimal. Busy clinicians tend to respond only to a flagged "H" or "L," meaning genuinely low-but-unflagged results are frequently missed.
What iron deficiency actually feels like
Long before someone becomes visibly "pale" iron deficiency tends to show up as much softer, easily dismissed symptoms: persistent fatigue (present in nearly 100% of women with non-anemic iron deficiency in the referenced study), brain fog, shortness of breath, underperformance relative to training, anxiety, low mood, and even loss of motivation or enjoyment for a sport someone previously loved. In athletes, this often gets misread as overtraining or insufficient rest rather than correctly identified as an iron problem.
Why athletes, specifically, are at risk
It's a common assumption that dialed-in, health-conscious athletes should be protected from nutritional deficiencies. but the physiology of intense exercise itself works against them:
Hepcidin. Physical stress from intense training triggers release of this hormone, which directly blocks iron absorption in the gut, meaning even a well-planned, iron-rich diet may not translate into adequate absorption.
Blood loss. Endurance athletes commonly experience small gastrointestinal bleeds (sometimes related to anti-inflammatory medication use) and "foot-strike hemolysis" - red blood cell damage from repeated impact, historically called march hemolysis in soldiers.
Restrictive eating. Particularly relevant in weight-sensitive sports like ballet and gymnastics.
What to actually do about it
Know your ferritin number. Don't wait for symptoms to become severe, and don't assume a "normal" lab result without checking the actual value against optimal ranges, not just the lab's flag.
Re-test after supplementing. Testing once, treating, and never re-checking is a common and important mistake - you need to confirm the intervention actually worked.
Timing matters. Somewhat counterintuitively, taking an iron supplement immediately after exercise (rather than in the evening or before training) appears most effective, based on athlete-specific research.
Be cautious with enteric-coated iron tablets. They're more expensive and tend to bypass the primary site of iron absorption, reducing their effectiveness.
If oral iron isn't tolerated or isn't working, don't wait indefinitely. Persistent nausea or a lack of improvement after roughly three months (or as little as four weeks in the context of anemia) is a reasonable trigger to move to intravenous iron rather than continuing to struggle with oral supplementation.
Don't stop investigating just because someone is "fit." Persistent, unexplained iron deficiency, even in an athlete, shouldn't automatically be attributed to training-related inflammation or diet. It's important not to overlook other potential causes of blood loss that warrant proper medical investigation.
The Common Thread
What ties these three topics together is a simple idea that runs through nearly every Innersight conversation: the basics are frequently overlooked, under-tested or dismissed as "normal" when they're not.
Creatine remains under-used because of outdated fears about side effects that don't hold up under modern dosing. Sleep issues go unaddressed because people assume persistent tiredness is just part of life. And iron deficiency slips through the cracks because standard screening waits until the problem is already severe.
In all three cases, the fix isn't complicated, it's about knowing your actual numbers, understanding what "normal" really means (rather than what's merely "not flagged"), and being willing to ask "why" rather than reaching for a quick fix.
Watch the replays of the relevant episodes to this Podcast Special at the links below:
Innersight Episode 22: Brain Gains - The Creatine Revolution Your Body's Been Waiting For
Innersight Episode 24: The Sleep Revolution - Why Your Breathing at Night Could Be Sabotaging Your Health
Innersight Episode 25: The Hidden Performance Killer: Iron Status in Athletic Populations
Additional resources:
InnerSight Episode 13: Unravelling Iron with Prof. Vernon Louw
This blog post is based on conversations featured on the Innersight Podcast and is intended for general informational purposes. It is not a substitute for personalized medical advice - please speak with your healthcare provider about your individual health needs.
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