Dr. Colbert’s Broadcast • Mitochondria, Deep Sleep & Cellular Energy • Episode 3
Why You’re Always Tired (It’s Not Just Age) | Dr. Don Colbert, MD Ep. 3
Most people accept exhaustion as the price of getting older. Dr. Colbert doesn’t, and he has a reason rooted in cell biology rather than resignation. In this episode of Dr. Colbert’s Broadcast, Dr. Don Colbert, MD, Kyle Colbert, and Mary Colbert walk through what actually drains your energy: not enough deep sleep, and a shrinking population of mitochondria. Then they cover what the newer science says about restoring both, including glycine, urolithin A, paraxanthine, NAD+, and functional mushrooms.
Persistent fatigue is a symptom, not a diagnosis. Low iron, low B12, thyroid dysfunction, sleep apnea, depression, diabetes, kidney disease, and certain cancers all present as exhaustion, and none of them is fixed by a supplement. Mary Colbert stops the episode to make exactly this point, and it belongs at the top rather than the bottom.
Before you build a supplement stack, get blood work and be evaluated. Fatigue that does not improve when you fix your sleep is information. Treat it that way. Seek prompt medical attention for fatigue accompanied by chest pain, shortness of breath at rest, fainting, unexplained weight loss, or new confusion.
Your energy factories are disappearing
Dr. Colbert opens with a story that stayed with him. His grandson Timmy, then three years old, got stuck behind an elderly man crossing a parking lot at Target and announced, “You’re slow as a turtle.” The man apologized: this is what happens when you get old.
Dr. Colbert’s objection is that this is not simply what happens. There is a mechanism, and it has a name.
Nearly every cell in your body contains mitochondria, the structures that produce ATP, the currency your body spends on everything it does. They are not distributed evenly, and the distribution tells you a lot about what your body prioritizes.
| Tissue | Mitochondria per cell | Why |
|---|---|---|
| Heart muscle | About 5,000 | It never stops. Not for a second, for your entire life. |
| Brain & skeletal muscle | A few thousand | High, variable demand. Your brain is 2% of body weight but burns about 20% of your energy. |
| White fat, tendons, connective tissue | Very few | Not metabolically active. Dr. Colbert links this to why tendons heal so slowly and injure so easily. |
| Red blood cells | Zero | They carry oxygen rather than burning it, since mitochondria would consume the cargo. |
Here is the problem: as we age, we produce fewer and fewer mitochondria. Fewer energy factories, less energy. That is the biological version of “slower than a turtle,” and it explains why so many people describe hitting 70 and feeling like something switched off.
Why studying makes you genuinely tired: Your brain’s enormous energy draw has a byproduct. Burning oxygen produces free radicals (hydrogen peroxide, hydroxyl radicals, singlet oxygen), and that oxidative exhaust damages the very mitochondria producing the energy.
It is a loop: high demand creates damage, damage reduces capacity, reduced capacity feels like exhaustion. Which is precisely why the repair mechanisms in the next sections matter more than any stimulant.
“If you’re only getting 10 or 15 minutes of deep sleep, you’re going to be exhausted. You’re never going to recharge.”
Dr. Don Colbert, MD, in this episode
Before any supplement: are you actually sleeping?
Dr. Colbert is blunt that most energy deficits trace back to one thing: not enough deep sleep. Not hours in bed. Deep sleep specifically.
This distinction catches people out. You can spend eight hours in bed, wake without remembering a single awakening, and still be running on 10 minutes of slow-wave sleep. A wearable such as an Apple Watch or Oura Ring, or a formal sleep study, will tell you where you actually stand. Mary spent a long time pushing him to get one.
The picture she describes is one a lot of families will recognize. He would sit down after work and be asleep within three minutes. She stopped going to movies with him, because the moment the lights went down he was gone, then wanted to rewatch the half he had missed.
Glycine, at 3 grams
His fix was unglamorous and inexpensive. Glycine, an ordinary amino acid, at 3,000 mg (3 grams) before bed. He describes going from roughly 10 minutes of deep sleep to over an hour, and Mary noticed the change before he mentioned it. He is back to leaping out of bed in the morning, which she reports as a mixed blessing.
The research behind that number: The 3-gram dose is not arbitrary. It comes from a body of Japanese research, most notably a polysomnography study in which volunteers given 3 g of glycine before bed showed measurable changes in sleep architecture, including shortened time to fall asleep and to reach slow-wave sleep, alongside improved subjective sleep quality and reduced next-day fatigue.
Glycine also lowers core body temperature slightly, which is one of the physiological signals that initiates sleep. It is inexpensive, widely available, tastes faintly sweet, and has a good tolerability record. As sleep interventions go, it is unusually low-risk for the potential return.
The unglamorous fixes that mattered just as much
Worth noting, because these cost almost nothing and get overlooked in favour of supplements:
An ergonomic pillow, plus treating chronic nasal congestion from a deviated septum. Obstructed breathing fragments sleep whether or not you wake up aware of it.
Xylitol tablets that adhere to the cheek overnight. He had been waking three or four times a night from his mouth drying out. Xylitol also helps prevent cavities.
Phone and laptop go in another room. Not face-down on the nightstand, another room. This is the rule with no exceptions.
Waking repeatedly, or unrefreshed despite adequate hours? Get evaluated for sleep apnea before assuming supplements will fix it. Loud snoring, witnessed pauses in breathing, morning headaches, and daytime sleepiness are the classic signs. Untreated apnea raises cardiovascular risk independently, and no amount of glycine addresses it. A sleep study is the right next step, not a bigger stack.
Urolithin A: recycling worn-out mitochondria
This is the segment Dr. Colbert is most animated about, because it challenges an assumption: that mitochondrial decline runs one direction only.
Mitophagy is your body’s process for dismantling worn-out mitochondria and building fresh ones from the parts. One compound that appears to promote it is urolithin A, and the interesting thing is that you cannot eat it. It is a postbiotic: your gut bacteria manufacture it from raw materials you supply.
Those raw materials are ordinary foods. Strawberries, blueberries, raspberries, cherries, pomegranate, and walnuts all contain the precursor compounds (ellagitannins). Your microbes do the conversion.
The catch, and it is a big one: only about 30 to 40% of people host the microbial diversity required to make that conversion. For the remaining 60 to 70%, courses of antibiotics and years of dietary sugar have thinned out the anaerobic bacteria that do the work. Two people can eat identical bowls of berries and get entirely different results.
The bacteria that matter here include Bifidobacterium longum, Bifidobacterium adolescentis, and Akkermansia muciniphila, the last of which Dr. Colbert prescribes frequently and takes himself. Akkermansia is a mucin-degrading species that helps maintain the gut lining and has become one of the more closely studied organisms in metabolic health.
His objection to buying it in a bottle
Studies typically use 500 to 1,000 mg of urolithin A, with most using the higher end. At those doses you are looking at roughly $100 to $200 a month, which prompts a characteristic aside from Kyle about his father’s talent for finding the most expensive patented ingredient in any category.
Dr. Colbert’s alternative is to rebuild the bacteria that make it, then feed them properly. His own nightly routine: a handful of walnuts, a small serving of pomegranate juice (about half a small paper cup, not a glass), and mixed berries. He puts the cost at around $30 a month.
Where the evidence currently stands: Urolithin A is one of the better-supported compounds in the longevity category, which is not a high bar but matters here. A randomized controlled trial in middle-aged adults found improvements in muscle strength and in biomarkers of mitochondrial health, and subsequent trials and a 2025 systematic review have continued to examine effects on muscle strength and physical performance.
Two honest caveats. Effect sizes in these trials are meaningful but modest. This is not a transformation in a capsule. And the food-and-microbiome route Dr. Colbert prefers, while sensible and far cheaper, has not been tested head-to-head against supplementation. If you go that way, you are reasoning from mechanism rather than from trial data. That is a legitimate approach, but it is worth knowing which one you are doing.
Intermittent fasting does the same work for free
Fasting for roughly 16 hours triggers autophagy, the clearing out of worn cellular components, and mitophagy alongside it. The same recycling process, no supplement required, no cost.
Dr. Colbert’s honest caveat is that most people simply will not do it, which is why the nutritional route matters. Mary, who has lived an intermittent fasting pattern for years without particularly framing it that way, suspects it explains a good deal of her own energy, an observation that lands during the episode as she works it out mid-conversation.
Intermittent fasting is not for everyone. Do not begin without medical guidance if you take insulin or sulfonylureas for diabetes, where fasting can cause dangerous hypoglycemia; if you are pregnant or breastfeeding; if you have a history of disordered eating; if you are underweight or frail; or if you take medications that must be given with food.
Older adults should also be careful that a compressed eating window does not quietly reduce protein intake, since preserving muscle mass matters more with age, not less.
The caffeine problem, and what comes after it
Dr. Colbert draws a line between two things people conflate: energy, and stimulation. Caffeine is a central nervous system stimulant that raises adrenaline. You get several hours, then you crash. Take it late and it erodes the deep sleep that would have restored you, so tomorrow starts lower than today did.
That is the loop worth seeing clearly. The tireder you are, the more caffeine you use; the more caffeine you use, the worse you sleep; the worse you sleep, the tireder you are.
Two problems he considers serious
Caffeine is processed by the liver, and people are genetically either fast or slow metabolizers, and most of us have never been told which. In slow metabolizers it lingers for many hours, quietly dismantling deep sleep long after the alertness has faded.
Dr. Colbert was drinking two to three cups each morning with a homocysteine around 14. Above 10 is considered high. Elevated homocysteine is a recognized risk factor for memory loss, fatigue, and arterial plaque. Cutting to one cup daily brought him below 10, where it has stayed.
Paraxanthine: what caffeine becomes anyway
Roughly 80% of the caffeine you drink is metabolized into paraxanthine. Dr. Colbert’s argument is simple: why not skip to the metabolite? Kyle reframes it neatly in the episode as cleaner fuel.
Paraxanthine appears to support short-term memory, focus, attention, and alertness. It clears the body faster than caffeine, does not require liver metabolism the same way, tends to carry fewer side effects, and does not appear to raise homocysteine. Provided you avoid it after 3 p.m., it is less disruptive to sleep.
Keeping this in proportion: Paraxanthine is a genuinely interesting ingredient with published safety assessments and early human and animal work on cognition and neuroplasticity. It is also new, and that cuts both ways.
Caffeine has a century of research and billions of person-years of use behind it. Paraxanthine has neither yet. The comparative claims are promising rather than settled, and much of the head-to-head data is preliminary. It is still a stimulant: the same cautions apply regarding pregnancy, anxiety disorders, arrhythmias, and uncontrolled blood pressure, and it should not simply be stacked on top of your existing coffee.
NAD+ and the last step of energy production
NAD+, or nicotinamide adenine dinucleotide, is a coenzyme that shuttles electrons into the electron transport chain, the final stage where ATP is actually made. Levels decline substantially with age, which makes it a natural target.
Dr. Colbert calls it one of the most striking supplements he has used, and makes a point worth repeating: with a multivitamin you are taking it on faith, whereas with NAD+ he describes noticing clarity and energy within about 15 minutes.
A clarification on the biochemistry: The terminology moves quickly in this segment. NAD+ itself is not what is in most oral products. What you take is a precursor your body converts. The most studied are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). Divine Health’s NAD+ Powder uses nicotinamide riboside chloride at 600 mg per serving.
This matters when you are comparing products: “NAD+” on a label almost always means a precursor, and which one, at what dose, is the useful question.
On the evidence: oral NR reliably raises blood NAD+ levels, and that part is well established. Whether raising the number produces the benefits people want is the live question, and the answer is still developing. A 2025 randomized controlled trial in long-COVID patients reported improvements in fatigue and cognitive symptoms, which is among the more encouraging clinical results to date. Trials in healthy aging have been more mixed.
On the injectable protocol: Dr. Colbert describes using injectable NAD+ in his clinical practice with patients who have chronic fatigue, fibromyalgia, or persistent brain fog, and with patients over 70 who have lost their energy, often getting them back to walking, exercising, and playing pickleball. That is supervised medical care delivered after examination, and it is not something to source or attempt on your own. The oral products discussed here are a different thing entirely.
Functional mushrooms
Medicinal mushrooms have been used in China and Japan for more than 2,000 years, and the modern evidence base has grown considerably. Dr. Colbert reports patients describing a noticeable lift within 10 or 15 minutes, and clarifies, with the timing of a man who has been asked before, that he means culinary and medicinal mushrooms, not the other kind.
A natural energy booster that supports cellular ATP production, the most directly relevant of the group to this episode’s theme.
Known in Chinese tradition as the mushroom of immortality. An adaptogen that helps calm the nervous system and support the stress response, which, given the sleep discussion above, may be the most useful one for a tired person.
Stimulates nerve growth factor and is associated with brain repair and memory support. This is the one in Brain Zone Advanced.
Supports immune function. Shiitake, maitake, and turkey tail belong to the same family of options.
Two practical notes. Mushroom products vary enormously in what they actually contain. Look for extracts specifying fruiting body rather than mycelium grown on grain, where much of the weight is residual starch. And check interactions: reishi may affect platelet function and matters if you take anticoagulants or have surgery scheduled, and people with mushroom allergies or on immunosuppressants should speak with their clinician first.
What’s actually robbing your energy
Dr. Colbert’s list, in the order he gives it. Most people scanning this will find two or three that apply, and fixing those beats adding anything.
The single largest factor, and the one most likely to make everything else irrelevant if unaddressed.
Not a character flaw, but a physiological drain with measurable effects.
His phrasing: when you cannot say no, other people’s problems become your problems. He directs this particularly at people whose faith makes them feel obligated to say yes, and argues that saying no kindly is a skill worth developing.
His own rule: one cup, in the morning, nothing after 3 p.m.
He is specific: bread at lunch ends his afternoon. If a meal reliably makes you want to lie down, that is data.
The quiet accumulators. Individually small, collectively decisive.
Your next-30-days action plan
- 1Measure your deep sleep before changing anything. A wearable for two weeks gives you a baseline. Without one you are guessing, and you will not know whether anything worked.
- 2Get blood work first. Iron and ferritin, B12, thyroid panel, blood sugar. Rule out the causes a supplement cannot touch before you build a stack on top of them.
- 3Move your caffeine cutoff to 2 p.m. for two weeks. Free, reversible, and for slow metabolizers it can be the single biggest change on this page.
- 4Phone and laptop out of the bedroom tonight. Not face-down. Another room. Buy an alarm clock if that is the obstacle.
- 5Add the mitochondria foods nightly. A handful of walnuts, a small serving of pomegranate, mixed berries. Cheap, pleasant, and it feeds the bacteria doing the work.
- 6Change one thing at a time. If you start five supplements at once and feel better, you have learned nothing about which one to keep buying.
Divine Health products and resources related to this episode
These are supportive wellness tools that fit the nutritional themes of the broadcast. They are not treatments for any medical cause of fatigue, and they are not substitutes for testing, evaluation, or prescribed care.
NAD+ Powder
Named directly by Dr. Colbert during the energy discussion, the lemon-lime powder he mixes during the episode. Nicotinamide riboside chloride at 600 mg per serving, for cellular energy and cognitive support.
Brain Zone Advanced
Referenced in the functional mushroom segment. Combines Lion’s Mane at 1,000 mg with citicoline, tyrosine, and 7,8-dihydroxyflavone for focus, memory, and brain cell support.
Organic Red Supremefood
The most directly relevant product to the urolithin A discussion: a berry blend of 10 organic fruits with probiotics, enzymes, and fiber. These are precisely the ellagitannin-rich foods your gut bacteria convert.
Fermented Green Supremefood
Supports the microbiome side of the equation. 14 organic fermented vegetables and grasses with a prebiotic inulin and Bacillus coagulans blend plus digestive enzymes.
Fiber Zone
Prebiotic fiber feeds the anaerobic bacteria discussed in the urolithin A segment. A blend of soluble and insoluble fiber including psyllium and prebiotic inulin.
Live Long and Strong
Dr. Colbert points to this book during the episode as where he lays out the key health markers and tests in full detail, including the ones Mary urges viewers to have checked before self-treating.
Dr. Colbert also offers his full energy supplement list by request. Email info@divinehealth.com and the team will send it over.
Supplement safety: Dietary supplements are not a substitute for evaluation and treatment of an underlying medical cause of fatigue. Several ingredients discussed in this episode, including reishi and other functional mushrooms, can interact with blood thinners and other medications. Talk with your healthcare professional before starting anything new, and bring your full list to every appointment.
Questions to take to your next appointment
- ✓Could my fatigue have a medical cause such as iron, B12, thyroid, blood sugar, or sleep apnea?
- ✓Should I have a sleep study, given how much of this comes back to deep sleep?
- ✓Could any medication I take be contributing to my fatigue or disrupting my sleep?
- ✓Is glycine at 3 g before bed reasonable for me, given my other medications?
- ✓Is intermittent fasting safe for me specifically, or does something in my history rule it out?
- ✓Do any of my supplements interact with what you have prescribed?
Watch, share, and start with sleep
The message of Episode 3 is not that exhaustion is inevitable after 70. It is that fatigue has mechanisms, and mechanisms can be worked on. Start with deep sleep, because nothing else in this article works without it. Then feed the bacteria that rebuild your mitochondria. The rest is refinement.
Sources and further reading
- Yamadera et al., Sleep and Biological Rhythms: Glycine ingestion improves subjective sleep quality, correlating with polysomnographic changes
- Singh et al.: Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health, a randomized trial in middle-aged adults
- Systematic review (2025): Effects of urolithin A supplementation on muscle strength, muscle mass and physical performance in humans
- Frontiers in Toxicology: Paraxanthine safety and comparison to caffeine
- Paraxanthine enhances memory and neuroplasticity more than caffeine (preclinical)
- eClinicalMedicine (2025): Effects of nicotinamide riboside on NAD+ levels, cognition, and symptom recovery in long-COVID, a randomized controlled trial
- American Heart Association: Sleep and cardiovascular health
