The search to reverse aging and live forever has fueled human pursuits since the beginning of time...
Medieval alchemists sought to create a philosopher's stone that would grant immortality. Explorer Juan Ponce de León looked for a Fountain of Youth in Florida.
So far, no one has discovered the key to immortality. The average life expectancy in the U.S. is about 79 years. But other species enjoy much longer lives than us...
The world's longest-living animal, Ming, was an ocean quahog – a type of clam. It holds the current record at 507 years old.
The American lobster, which is more similar to humans than a mollusk, belongs to a group of organisms that is considered "biologically immortal." As long as a lobster doesn't fall victim to a predator or outside injury, its cells don't seem to deteriorate with age.
While we haven't found the key to immortality, there are steps we can take to help us live healthier lives for longer.
On Tuesday, we explored how exposing your body to a little bit of heat stress flips the switch on a longevity gene called FOXO3. We learned that FOXO3 is the "project manager" of sorts that tells your body to start cleaning up cellular waste and start repairing DNA.
But FOXO3 doesn't really do the physical work itself. To understand how the repair actually happens, we have to look at the specialized repair team...
While FOXO3 handles the "big picture" commands for repair and maintenance, it's up to the heat shock proteins ("HSPs") to get that job done.
We wrote about HSPs a few months ago, but it's worth a quick refresher on how a simple soak activates them...
The health of your cells depends on the proteins within them. That includes protein creation, destruction of old or damaged protein, and properly folded proteins. HSPs chaperone this whole process.
HSPs protect cells from heat and other stressors. They also help with communication between cells, regulating the life cycle of a cell, and helping eliminate damaged proteins.
Now, back to the idea of protein folding. Proteins are made up of amino-acid building blocks. In order for proteins to function normally, they have to be perfectly folded into specific shapes.
As we age, though, our proteins tend to get "misfolded." And they can clump up, too... One infamous example is the clumps of amyloid plaques and tau tangles that are the hallmark features of Alzheimer's and Parkinson's diseases.
But immerse your body into a hot environment, and your body floods your system with HSPs. They can jump in and get a wonky protein to fold correctly. Or if the protein is too damaged to be saved, HSPs tag it for destruction before it can form a toxic clump.
In fact, a 2016 study of regular sauna usage among 2,315 older men over the course of 20 years found that frequent, intense heat exposure can lower the risk of dementia and Alzheimer's by up to 65%.
But "steam cleaning" your brain isn't the only benefit of challenging your cells with a bit of heat...
Heat exposure also fights chronic, low-grade inflammation, or "inflammaging." We want a bit of swelling after we stub a toe or get a paper cut. This controls damage to your body and fights infection. But over decades, inflammaging can damage your arteries, joints, and organs.
And back to that 2016 sauna study, researchers found that regular heat seekers had significantly lower C-reactive protein ("CRP") levels, marking a steep drop in systemic inflammation.
Another remarkable benefit of heating up your body is that it keeps our blood vessels young by keeping them flexible.
Research has found that sauna bathing can significantly boost levels of nitric oxide in your blood. This molecule is crucial for getting the walls of your blood vessels to relax and widen to improve oxygen- and nutrient-rich blood flow, as well as keeping your vessels clear of clots. And heart-disease patients tend to have reduced levels of nitric oxide.
A March 2025 review in Frontiers of Cardiovascular Medicine found that sauna use could help prevent peripheral artery disease – a disease where narrowed arteries hamper blood flow to the limbs, afflicting up to 30% of seniors.
Use the Sauna to Unlock Natural Antiaging
Let's face it: outfitting your home with a private sauna can cost thousands of dollars, and driving to a spa just to sweat isn't always practical.
Fortunately, you already have a longevity tool sitting right in your house...
A piping-hot bath unlocks the exact same antiaging mechanisms in your cells.
A 2020 study of more than 30,000 healthy Japanese adults aged 40 to 59 over the course of 19 years linked a daily hot bath to a 28% lower risk of cardiovascular disease, and a 26% lower stroke risk.
Another bonus with a hot bath is that the weight of the water pushes against your skin in what's called hydrostatic pressure. This pressure is helpful for "squeezing" blood from your legs and abdomen back to your heart.
That means greater stroke volume – which is the amount of blood pumped per beat – to give your heart a big workout... all while sitting perfectly still and basking in the warmth. (You still need to exercise the rest of your body, though.)
In fact, one recent study from the University of Oregon said hot-water immersion in a bath provided even better health benefits than a sauna.
To get started, the key is frequency. Do what I do and get your heat treatment at least three or four times a week, aiming for 15 to 20 minutes per session.
The average onsen temperature is around 105 degrees Fahrenheit. But if you're new to heat therapy in your tub, start lower, at around 100 degrees Fahrenheit. Try to sink down so that the water comes up to your neck to maximize hydrostatic-pressure coverage.
Be careful, though, because the heat can lower your blood pressure. So if you already have low blood pressure, let your doctor know you're interested in heat therapy. With your doctor's approval, you can try starting with five to eight minutes in the tub... then adding a minute or two per session if you feel fine.
And for folks with orthostatic hypotension (where blood pressure can plummet upon standing), get out slowly... Sit on the edge of the tub or a bench for a minute before fully standing.
Regardless of your blood pressure, I also recommend that folks drink plenty of water before and after heat therapy to prevent dehydration.
Note that you can't get this benefit from a hot shower. You wouldn't get the hydrostatic pressure, and it's hard to pin down a precise water temperature.
Here are a couple more things to keep in mind...
- Don't do double-duty with your regular bath. With heat treatment, you want to stay immersed in hot water for a specific amount of time. It's not the time to soap yourself up.
- Respect your physical limits. If you struggle to lie down in a bathtub or safely get back out again, look into alternatives like a local sauna or even targeted heat wraps. A nonslip mat on the bottom of the tub might help.
However you do your heat treatment, you'll follow the example of Masazo Nonaka.
By challenging your cells with a bit of thermal stress, you're activating an ancient survival program coded into your DNA to clean your cells, protect your brain, and keep your arteries wide open.
P.S. We hope you enjoyed this two-part series this week, originally published in an issue for Retirement Millionaire subscribers. For more low-cost, high-reward health interventions and low-risk wealth-building strategies, try out a subscription today.
What We're Reading...
- Did you miss it? Harness the antiaging secret in your bathroom.
- Something different: Meteorite crashes through Houston home.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
March 26, 2026