Airplanes don’t contain less oxygen by percentage. The cabin air still contains about 21% oxygen, just like the air at sea level. The difference comes from pressure. As altitude increases, atmospheric pressure drops, so the partial pressure of oxygen drops with it. Aircraft pressurization keeps the cabin far more comfortable than the outside environment, but cabin pressure still sits below sea-level pressure.

That lower pressure means less oxygen pressure with every breath. Your lungs have less pressure pushing oxygen into your blood, which helps explain why SpO₂ can fall during a flight.

On some flights, my SpO₂ would be around 94 or 95%. But I noticed that when I drank carbonated water, the number would go higher.

Most people think of carbon dioxide as a waste product that your body needs to get rid of. But your body also uses CO₂ to regulate oxygen delivery. When CO₂ rises in your blood, blood pH falls (becomes more acidic) and hemoglobin releases oxygen more readily. That’s the Bohr effect.

Your muscles use this system every time you exercise. Working muscles produce more CO₂ as they use energy. The rise in CO₂ helps hemoglobin release oxygen where your tissues need it.

Carbonated Water and Oxygen

Researchers have tested what happens when you add CO₂ to a low-oxygen environment.

In one human study, healthy adults breathed low-oxygen air with or without added CO₂. Adding CO₂ increased arterial oxygen tension, oxygen saturation, and cerebral oxygenation. In other words, adding CO₂ helped more oxygen get into the blood and increased oxygen delivery to the brain, even though the participants were breathing low-oxygen air.

A separate 2021 study looked specifically at CO₂-containing drinking water. Researchers gave 39 healthy adults about a liter per day during the treatment period. After the treatment period, their SpO₂ increased.

That finding lines up with what I saw on airplanes.

In the full article, I’ll show you exactly how to test this on your next flight.

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But one of the simplest ways to stimulate it costs nothing. Just sprint.

You don’t need to spend an hour on a treadmill or turn every workout into an endurance event. A short burst of very hard work can create a strong hormonal response, and you can build that into a workout that takes only minutes.

Your Body Already Makes Growth Hormone

Your pituitary gland releases growth hormone in pulses throughout the day. Exercise can trigger one of those pulses, especially when you push the intensity high enough.

A 2002 cycling study had nine men perform a 30-second maximal sprint on a cycle ergometer. Growth hormone surged to an average of 18.5 μg/L and stayed elevated for about 90 to 120 minutes.

This is how I’ve been working out for years. Short, hard efforts give your body a signal to get stronger.

In the full article, I’ll show you:

• The science behind sprinting

• The two-sprint protocol I use to stimulate growth hormone

• Exactly how to do it at home or at a local gym

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Your liver makes ketones when glucose availability drops and your body starts using more fat for fuel. That happens during fasting, prolonged exercise, carbohydrate restriction and ketogenic diets.

But ketones do more than give your brain another fuel source. Beta-hydroxybutyrate, or BHB, also acts as a signaling molecule with positive effects on inflammation, oxidative stress, energy metabolism and brain function.

Ketones are useful but I don’t think you need to stay in ketosis all day, every day. I want metabolic flexibility. I want to use glucose when I need glucose and ketones when I want ketones.

And you don’t have to spend your life fasting or eating a strict ketogenic diet to raise your ketones.

Your Brain Can Run on Ketones

Your brain normally gets most of its energy from glucose. When glucose availability drops, your liver makes ketones from fatty acids. The main ketones it makes are beta-hydroxybutyrate and acetoacetate. Your brain can take those molecules up and use them to make energy.

That gives your brain another fuel source. Ketones are a cleaner-burning fuel for your brain. They get into your mitochondria and give your cells a steady supply of energy while reducing some of the oxidative stress that comes with glucose metabolism. That’s one reason raising ketones can make you feel significantly more alert, focused and energized.

BHB also reduces inflammatory signaling in studies, including ones looking at brain inflammation.

Check out what it does in Alzheimer’s. Amyloid-beta is one of the hallmarks of Alzheimer’s disease, and the small amyloid-beta clumps called oligomers can trigger inflammation in the brain. In a 2023 study, researchers exposed human brain immune cells called microglia to these amyloid-beta oligomers. BHB reduced the inflammatory response and helped restore the cells’ ability to clean up cellular debris.

We also have new human data. A 2026 randomized trial followed 60 people with early-to-mid-stage Alzheimer’s disease for six months. They tested a ketogenic diet with intermittent fasting against standard care. The intervention group had better cognitive outcomes than the standard-care group. The combination of a keto diet and fasting would have kept blood ketones elevated for more of the day, giving their brains a steady supply of an alternative fuel.

This is big. Alzheimer’s is one of the Four Killers I described in my longevity book, Super Human.

Metabolic Flexibility

I’ve used ketosis for years, and I think it has tremendous value. But I don’t want to lock myself into one metabolic state. There are times when I want to burn fat and produce ketones, times when I want carbohydrates available for hard training, and times when I want to eat a meal without worrying about whether it fits perfectly into a ketogenic diet. I want metabolic flexibility.

A strict ketogenic diet usually means keeping carbohydrate intake very low, often around 20 to 50 grams of net carbs per day. That can work, and I’ve used it myself. But keeping carbs that low all the time can trash your hormones long-term.

Carbohydrates also have a place in high-intensity exercise because your body can use glucose quickly when energy demand spikes.

I don’t see ketosis and carbohydrates as opposing teams. I want the ability to use both.

In the full article, I’ll show you:

• How a specific oil can raise ketones without a keto diet

• A drink that raises ketones even if you’re eating carbs

• How I use ketones for more energy

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I’ve heard all of it.

I don’t recommend flaxseed.

In June 2026, Germany’s Federal Institute for Risk Assessment (BfR) published a new warning about the risks of flaxseed. The agency recommends that adults limit raw flaxseed to 15 to 20 grams per day and says young children should avoid raw flaxseed altogether.

That’s a strange amount of caution for a food the wellness industry tells you to add to your smoothie every morning.

Flax Has a Defense System

Flaxseed naturally contains cyanogenic glycosides, compounds that can release hydrogen cyanide, a highly toxic gas. When you crush, chew or grind the seed, you break open its cells and bring those compounds and enzymes together, which then releases hydrogen cyanide.

One note is that heat inactivates the enzymes involved in cyanide release, and hydrogen cyanide evaporates readily. So cooking can greatly reduce the cyanide issue. But most people aren’t grinding flax and cooking it. They’re grinding it and putting it straight into a cold smoothie. Plus, later on I’ll tell you why heating it up is a terrible idea too.

In the full article, you’ll get:

• The other toxin hiding inside flaxseed

• Why flax’s famous “omega-3” isn’t the same as the omega-3 in fish

• What I think about flax lignans and flax oil

• A super smoothie recipe with no flax

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Maybe your body knows something that you don’t.

Your brain likes comfort.

Give it enough comfort for long enough, and ordinary things can start to feel less exciting. You get used to the same food, the same temperature, the same entertainment, the same easy dopamine hits.

Then you do something uncomfortable on purpose like a cold plunge, a hard workout, or a super hot sauna. Something that makes you want to stop. When it’s over, you feel surprisingly good.

That’s the idea behind BICEP: Brief Intentional Conscious Exposure to Pain.

The key is that the stress is intense, but temporary. You give your brain a short, controlled stressor and then let yourself recover.

And your brain responds. Cold exposure can send dopamine and norepinephrine soaring. One study found a 250% increase in plasma dopamine after cold-water immersion.

In the full article, I’ll show you:

• What happens in your brain when you deliberately expose yourself to discomfort

• Why pain can feel surprisingly good

• How to use controlled discomfort the right way

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It’s called lipopolysaccharide, or LPS, and certain bacteria make a lot of it. It’s a type of endotoxin.

LPS forms part of the outer membrane of Gram-negative bacteria. When these bacteria die or shed pieces of their membranes, they release LPS into your gut.

You don’t want excessive amounts of it sitting there, and you don’t want too much of it getting into your bloodstream.

In the full article, I’ll show you:

• How your gut bacteria trigger inflammation

• The everyday food that changed endotoxin levels in humans

• The drink that can open the door to bacterial toxins

• The mistake people make when trying to fix their microbiome

• What I would eat if I wanted to lower LPS production

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You can test those measurements before and after you change your diet, supplements or lifestyle.

A 2026 analysis in Nature Medicine pulled together 51 human intervention studies and more than 3,000 samples. Researchers tested 16 different epigenetic clocks and found measurable changes in several of them after various interventions.

In the full version, I’ll cover:

• The supplement that slowed three epigenetic aging clocks

• The multivitamin trial that changed two biological-aging measures

• Foods that may lower biological age

• How to track changes over time

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I’ve been talking about using 40 Hz blinking light for years. In mice with Alzheimer’s-like brain changes, 40 Hz light reduced amyloid-beta and changed the behavior of microglia, the immune cells that patrol the brain. The microglia became more active around amyloid deposits, where they helped engulf and clear cellular debris and unwanted material.

Then researchers added sound. And they started seeing changes beyond amyloid.

Human studies have now tested 40 Hz light and sound in people with Alzheimer’s disease. Some have found changes in brain activity, brain structure and memory.

In the full version you’ll get:

• Why researchers started targeting 40 Hz

• 40 Hz light in human and animal studies

• How 40 Hz connects to your brain’s waste-clearance system

• How to do this specific light therapy at home

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Then somebody decided to sell it as candy for children, and the rest of the developed world watched that happen with their mouths open.

A new study of more than 130,000 adults with chronic insomnia found that people with documented melatonin use for at least a year had about a 90% higher rate of heart failure over the next five years.

That does not prove melatonin caused heart failure. This was an observational study, and the findings were presented as a preliminary research abstract, not a peer-reviewed paper.

But the finding deserves your attention.

In the full version you’ll get:

• What your body makes at night, and what the bottle gives you

• What dose wins in research

• What’s in melatonin gummies besides melatonin

• What to take instead

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Incandescent lights emit a continuous, smooth full spectrum of visible light and infrared. LEDs don’t. Those bulbs I bought back before the rules changed are protecting my vision and my skin right now.

I started TrueDark in 2014 for the same reason. Junk light was already damaging people’s sleep and their eyes, but few people knew about it. Twelve years later the problem has gotten worse, and a federal rule that most people have never heard of is about to make it worse again.

In the full version you’ll get:

• How indoor lighting has changed

• Why most indoor lights suck

• The new 2028 standard for lighting

• What to do about it to get your light right

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You can have the ring, the mattress, the blackout curtains, the temperature and the magnesium, and still wake up feeling like you got hit by a truck. The input you forget is the air going into your lungs for the eight hours you spend unconscious.

Carbon dioxide may be climbing in your bedroom every night, taking the quality out of your eight hours of sleep. There's a number that tells you how bad your levels get, and it costs about two hundred dollars to see it.

In the full version you’ll get:

• What bedroom air does to your sleep

• What the number is really telling you

• What to do tonight to fix it

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I just didn't feel good on it. And I'm not really looking to do things that make me feel bad. So I stopped.

Since then rapamycin has become the most talked-about longevity drug on earth. Clinics prescribe it off-label and podcasters take it weekly. What you don’t hear about often are the side effects. Is there a way to get the benefits without actually taking rapamycin?

In the full version you’ll get:

• How rapamycin works

• Side effects of rapamycin

• The six things you can do to get the benefits without the downsides

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Peptides are expensive enough that getting the order wrong costs you lots of money. That’s the part I got wrong for a while, and maybe you are too.

I’m planning to live to at least 180, and I think that number is conservative. Deciding things ahead of the literature comes with the territory.

There are two mitochondrial peptides people are excited about right now. One of them has been through human trials. The other has never been given to a human in a controlled study, which hasn’t stopped anyone from selling protocols for it. There’s a specific order in which you should do these peptides, and it makes all the difference in what you get out of them.

In the full version you’ll get:

• The mitochondrial peptides and their data

• The order I use them in

• My timing and my phases

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I went down a rabbit hole trying to figure out why, and here’s what I found.

In the full version you’ll get:

• Why whale cells resist cancer

• The tiny genetic difference that lets a beaver repair cell damage better than a mouse, and live twice as long

• The compound already sold as a supplement that switches on the same repair gene in human cells

• What an actual human trial testing this right now is measuring, and when we’ll know if it works

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So I went looking for the mechanism behind it, and found a pulmonologist who’s spent 15 years mapping one pathway that most doctors never mention.

In the full version you’ll get:

• The breathing technique I did every morning for five years, and why it targets three separate parts of your lungs

• The one enzyme that keeps chronic lung inflammation going

• What years of antibiotics do to your lungs, separate from what they do to your gut

• What to do to help your lungs recover

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Right now there's a decent chance unmetabolized folic acid is sitting in your bloodstream, whether you take a supplement or not. Most people find out the hard way, if they find out at all.

In the full version you’ll get:

• Why folic acid isn’t doing what you think it’s doing

• What to take instead

• Who’s genetically set up to process it even worse, and how to tell if that’s you

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In the full version you’ll get:

• The biological pathways behind PQQ’s effect on your brain and your mitochondria

• What the human trials on cognition, sleep, and inflammation found

• The newest data on PQQ

• The absorption problem that cost me years and hundreds of dollars a month, and how to avoid making the same mistake

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A study published in Science in 2022 tracked over 10 million U.S. military members across two decades. Among people who developed MS, 97% contracted Epstein-Barr virus before their diagnosis. The researchers concluded EBV infection is a leading cause of multiple sclerosis.

The standard MS treatment strategy still focuses on suppressing the immune response, not eliminating EBV.

New research published this year in Science Translational Medicine is explaining the mechanism. The findings raise a question medicine has been slow to ask: if EBV helps drive MS, why isn’t the treatment targeting the virus?

In the full version you’ll get:

• Why the most common MS drugs work for a reason most doctors never mention

• The first major trial testing whether an EBV-targeted treatment reduces MS disease activity, and who qualifies

• What I’d do if I had a family history of MS

• Potential ways to keep EBV reactivation at bay

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A study published this month in Cancer Research by researchers at the Weizmann Institute found something else this drug class does, something nobody was studying it for.

The connection is cholesterol. Specifically, what cancer cells do with it when they try to spread, and what this drug class does to disrupt them.

The researchers validated the finding across cancer cell cultures, mouse models, and 20 years of health records from approximately five million people.

In the full version you’ll get:

• Exactly how sildenafil disrupts cancer cells

• What the sildenafil findings mean for tadalafil, the active ingredient in Cialis

• What my current protocol looks like

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A review published last month in Trends in Neurosciences by researchers at Victoria University looked at how physical activity regulates glymphatic function as your brain ages. The evidence comes primarily from animal studies, with early human research now adding support. In some animal studies, glymphatic clearance dropped by up to 90% in aged animals compared with young animals. Early human trials show you can improve markers of glymphatic function. Timing appears to be important.

I have been saying for years that exercise is one of the most important things you can do for your brain. What this review does is connect that recommendation to a specific, measurable biological pathway. Here is what the research shows.

In the full version you’ll get:

• The specific protein exercise affects in the brain’s waste-clearance system, what it does, and how aging disrupts it

• Why starting early is important

• The specific exercise protocol you can do to get the benefits

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