Bryan Johnson's 90-Day Sauna Experiment: Blood Pressure, Toxins, and a Fertility Lesson
Bryan Johnson
Bryan Johnson has tried plenty of unusual longevity interventions. He mentions bone marrow injections into a joint, removing his plasma, 9,500 minutes in a hyperbaric oxygen chamber, and receiving blood from his own son. Yet he had never committed to one of the oldest therapies there is: the dry, or "Finnish," sauna. In this video he explains why he held off and describes the protocol he eventually followed. He then reports what his biomarkers did over roughly 48 sessions, including a self-inflicted setback that he presents as a warning to other sauna users.
Why he waited
Johnson starts with Finland, where he says there are about 3 million saunas for 5.5 million people, "almost as many saunas as cars," and where about 90% of people use a sauna at least once a week. Because sauna is so embedded in the culture, he argues, Finnish researchers have done more work on heat exposure and health than anyone else.
The headline finding he cites comes from several long-term studies. They linked four or more dry sauna sessions per week with a roughly 40% lower risk of all-cause mortality. In other words, over the study period, participants were about 40% less likely to die of anything than people who didn't use a sauna. Johnson calls this "gigantic." In his framing, it exceeds the data for exercise and for a Mediterranean diet, and is matched only by losing weight when obese or by quitting smoking.
He gives three reasons he still didn't prioritize sauna. First, most of the research was done on Finns in Finland, which he describes as having a relatively small gene pool, so it was unclear whether other people would respond the same way. Second, Finns live in a cold climate and often plunge into cold water after a sauna, which he calls "basically a national sport." That raises the question of whether sauna works without the cold. Third, sauna produces some of the same effects as exercise, such as faster circulation, sweating, and a higher heart rate. He wondered whether it would add anything for someone who already works out daily, or whether it mainly helps people who don't exercise much.
That changed when his lead physician, Dr. Mike Malin, joined the team. According to Johnson, Malin told him the benefits were "way too good to ignore." In a clip, the physician says that as soon as he started working with Johnson he wondered why they weren't doing sauna.
The protocol
The team looked for the best evidence-based protocol. Johnson had a dry Finnish sauna installed at his house. Each session lasted 20 minutes at 200°F (about 93°C), seven days a week. He ties the daily frequency to study data showing all-cause mortality dropped by an additional 16% in people who did four to seven sessions per week instead of two to three. He says 20 minutes also matched how he felt: by minute 16 or 17, "you're pretty much done."
He often went into the sauna right after a workout. Electronics can't go inside because the heat would destroy them, so he left a timer where he could see it through the glass.
The team had three questions going in:
- Would sauna add benefits on top of exercise?
- Would it help remove toxins? Johnson says he knew he had high toxin levels after the Los Angeles wildfires.
- What would it do to fertility?
They recorded baseline biomarkers and planned to retest after 21 sessions.
Week one: heat, breathing, and a makeshift scalp cooler
Johnson had used saunas before at around 120–145°F, but he says 200°F was "next level." It is hot enough, he notes, that an egg white left inside would harden by the end of a session. Two problems showed up in the first session. Breathing the air felt like a "fire breathing dragon situation," and his scalp got so hot he worried the heat might burn his hair off.
For the breathing, he adopted a 4-6 pattern: four seconds in, six seconds out. He says it calmed him, and it also gave him something to do in a room with no electronics and no one to talk to. For his scalp, he put a towel on his head with an ice pack on top so the dry heat wouldn't dry out his scalp. He openly calls this "a pretty janky solution." It wasn't designed for saunas. The ice pack just happened to be in his freezer.
Night cramps and the electrolyte fix
A few days in, Johnson says he was "wrecked." He woke at night with severe cramps in his hamstrings and calves that made him jump out of bed, and he couldn't walk them off. The sauna itself was going fine, but his sleep got worse.
He raised it on a science call with his physician, who offered a hypothesis. A Finnish sauna heats the skin much faster than the core, which flips the usual core-to-skin temperature gradient and forces the body into overdrive. Johnson says the heart pumps blood up to 70% faster to move sweat to the skin. He compares the cardiovascular effect to zone 1 or zone 2 cardio. Sweat loss is heavy, roughly 0.6 to 1 liter per hour, so the physician suspected dehydration.
A Gatorade sweat patch confirmed it. Johnson turned out to be a "salty sweater." He reports losing 18 ounces of sweat and about 600 micrograms of sodium per session. He had been drinking enough to replace the water but not the minerals, which he says caused the cramps and other symptoms. The team increased his electrolytes by 50% before each session and 50% immediately after. His advice is to test whether you're a salty sweater and, if you are, to take enough electrolytes to avoid dehydration.
By day seven the cramps had eased, though his sleep was still poor. Johnson says that first week crashed him more than any therapy he had tried before. He adds that he loved it anyway.
First data: lower central blood pressure after seven sessions
After the first week, several of his vascular markers had improved. That included central systolic blood pressure, which he describes as his heart, brain, and major organs experiencing 5.83% less pressure.
His explanation is heat-induced vasodilation. As core temperature rises, the skin and peripheral blood vessels widen to release heat, so the same blood flow passes through with less force. That lowers pressure inside the arteries, makes them more flexible, and reduces strain on the heart and organs. Johnson finds it notable that the change appeared after only seven sessions. He takes that as a sign that the effective "dose" arrives relatively quickly.
Week two: could the sauna make toxins worse?
By week two, Johnson says, he looked forward to the sauna every day, especially after a hard workout. His cramps were gone, his sleep was slowly improving, and his vascular markers were rising. He didn't yet know what was happening with his toxin levels, and he raised a new concern: could the sauna actually increase exposure?
He wore cotton because he didn't know how clothing chemicals would interact with his skin at that heat. The team also wondered what materials the sauna itself was built from and whether they might be toxic at 200°F. They settled on three precautions:
- No water on the rocks. Water can contain PFAS ("forever chemicals"), and they worried heating it might make those airborne.
- Cotton clothing, not synthetics.
- A shower immediately afterward to remove toxins from the skin.
The "ice diaper"
Johnson wasn't sitting naked, as many sauna users do, because he was wearing what he calls an "ice diaper," which drew a lot of questions on social media. The team's literature review suggested heat could significantly harm fertility markers. So he put ice packs, taken from his supply for other therapies, on his testicles during sessions.
He explains that human testes operate 2–4°C below core body temperature. Even a 2°C rise, he says, can disrupt spermatogenesis for 74 days, one full cycle. He wasn't trying to conceive, but he says Project Blueprint aims to make every organ as vital as possible, and that includes sperm health.
Dry, wet, or infrared?
Viewers asked about other sauna types. Johnson explains that dry Finnish saunas have 10–20% relative humidity. A normal room has about 30–50%, and less in winter. Wet saunas run at roughly 100% humidity, which he says means they can't go above about 115°F (46°C) without burning or overheating you. He argues that most of the evidence, especially the long-term cardiovascular studies, is on Finnish saunas, where the combination of high heat and low humidity puts significant thermal and cardiovascular stress on the body.
Infrared saunas heat up faster and produce less steam and condensation. That makes them low-maintenance and popular with spas. But Johnson says they can't get much above 150°F, which doesn't match the conditions in the existing studies. In a clip, his physician adds that there are no comparable studies on infrared. So the team stuck with dry sauna.
Week three results: toxins, cardiovascular markers, and fertility
By week three, Johnson had no cramps, better sleep, and a steady routine. The team judged that any results should be visible by then.
He says the toxin results "shocked" them. Toxin levels dropped significantly across the board, and three went from abnormally high to undetectable. He calls it beyond what they expected and the best toxin result he had ever received. As far as the team could tell, the outcome was fairly unique in the scientific literature. He says it "seemed to suggest" sauna is potentially one of the best things you can do to detox. Note that this is his interpretation of his own results, not an established finding.
After 23 sessions, his cardiovascular markers had kept improving. Central pressure readings were down significantly, and his resting heart rate had dropped 4.4%. He calls resting heart rate a major marker of recovery and fitness.
His fertility markers had improved by 31% after 21 days. He says these were his best sperm health numbers to date, six times above the clinical threshold for fertility. He jokes about whether to mention this on first dates. He also flags an open question: did fertility improve because sauna boosted blood flow while the ice pack prevented heat damage, or would an ice pack alone produce similar results? Many people had asked him to pair cold plunges with the heat, but he says that will have to wait, since the goal was to test sauna on its own.
Part two: a break, then removing the ice
The experiment was then interrupted. Johnson traveled to Europe for 11 days, to Scandinavia, "ironically," and had no time to sit in a sauna for 20 minutes a day. When he returned, the team started a second phase aimed at 48 total sessions. It had two objectives. The first was to see whether results would keep improving, plateau, or fade as his body adapted to the stress, possibly erasing the cardiovascular gains. The second was to stop icing his testicles for two weeks to see what happened, or as he puts it, to "cook my boys at 200° F for science."
Final results
Fertility. Johnson describes his fertility markers as "demolished." Two weeks in a 200°F sauna without ice protection cut them by 50% across the board. He calls himself a cautionary tale and tells men to ice.
Vascular health. He says his blood pressure and vascular health improved substantially. His arteries became 25–50% more flexible, which by his account "de-ages" them by about 10 years and gives him the vascular markers of a healthy 20-year-old. He presents this as evidence that sauna is worth stacking on top of exercise, which answers his original question about whether it adds anything for someone who already trains daily.
VEGF. He also reports a surge in VEGF, the signal that tells the body to build more blood vessels. He compares blood vessels to roads carrying oxygen to every cell, and VEGF to a messenger calling for more roads, especially during repair or stress. Heat makes the heart pump harder and pushes blood through the vessels. He says this helps keep organs strong and slows age-related decline. Hyperbaric oxygen therapy had previously tripled his VEGF, and he says sauna boosted it another fivefold.
Johnson suggests these cardiovascular improvements "probably explain" the 40% reduction in all-cause mortality seen in the Finnish studies. This is his interpretation. His own conclusion is that sauna is worth doing.
His recommendations
Johnson ends with a protocol for viewers:
- Frequency: 3–5 sessions per week. He says the benefits seem to scale.
- Duration: 15–20 minutes.
- Temperature: 175–200°F (about 80–93°C).
- Type: dry over wet or infrared, optionally after exercise for stronger effects.
- Safety: build up to higher temperatures gradually, optionally breathe through a damp cloth to protect your airway, and replace electrolytes as well as water. Men should cool their testicles with non-toxic, BPA-free ice packs.
- Toxin avoidance: wear cotton or bamboo, or go naked. Avoid synthetic towels, synthetic blends, and heavily treated fabrics. Don't put water on the rocks. Shower immediately afterward. Choose a sauna built from non-toxic materials, and check the air quality if you can.
- Who should skip it: people who are pregnant, have a heart condition, or have other conditions he lists on screen.
For people without sauna access, he calls exercise the best alternative. It raises body heat, is essentially free, and achieves many of the same cardiovascular benefits. Based on his results, though, he says doing both is ideal.
In a closing update, Johnson says he restarted icing and his fertility markers have begun recovering, up about 30%. He expects a full recovery within a few more weeks. That recovery, and whether the ice pack alone could explain his earlier fertility gains, remain unresolved at the end of the video.
Look guys, I've done a lot of crazy stuff when it comes to health protocols. I've injected millions of young Swedish bone marrow into my joint. I removed all the plasma from my body. I've spent 9,500 minutes in a hyperbaric oxygen therapy chamber. And I even used my own son as my blood. But one thing I haven't tried yet, which is one of the oldest of all therapies, is a hot box, also known as a dry sauna.
Sauna has become insanely popular over the past couple years. What about the sauna, bro?
The more often you do sauna, the better.
Sauna is almost every day.
Regular sauna use reduced all-cause mortality.
So, why haven't I been doing this? To explain, let's look at the origins of sauna in Finland. There are 5.5 million Finnish, but 3 million saunas. That's almost as many saunas as cars. Who are these people? 90% of these Finns do sauna at least one time per week. And because of this, it makes sense that nobody's done more experimentational work on saunas than the Finnish, specifically heat exposure for health.
Multiple long-term studies linked four or more sessions of dry Finnish sauna per week with a 40% reduced risk of all-cause mortality. In other words, they were about 40% less likely to die from anything during the study compared to people who didn't do sauna. That number is gigantic. And to give you context on how big it is, a 40% reduction in all-cause mortality exceeds data around exercise and a Mediterranean diet. It's only matched by either losing weight when you're obese or by quitting smoking.
Now, this sounds great, but here's the caveat. Most of these studies were done on the Finnish in Finland. Finland has a relatively small gene pool, so does everyone else respond the same? Finns live in a very cold climate and often cold plunge after sauna. Jumping into ice holes is basically a national sport. So, does sauna still work without cold exposure? And even more importantly, sauna triggers some of the same effects as exercise: faster circulation, sweating, higher heart rate. So, would sauna add anything on top of my daily workouts? Or does it mainly help people who don't exercise much?
It's for these reasons that I didn't prioritize doing sauna. We prioritized other therapies for the past couple years. But that changed when my lead physician, Dr. Mike Malin, joined. He said, "Bryan, get the sauna right now. The benefits are way too good to ignore."
I love sauna. Sauna is like, I feel like as soon as I started working with Bryan, I was like, "Why aren't we doing sauna?"
So, like all things Blueprint, we went to the scientific literature and we said, "What is the best 30-day protocol to implement?"
I'd do dry Finnish sauna and get one installed at my house. Each session would last 20 minutes at 200° F, 83° C, and I'd go all-in at 7 days a week. This matches the study data that saw all-cause mortality drop by an extra 16% for people who did four to seven sessions per week instead of two to three.
I'm going to finish strong and then we're going to head off to the sauna.
All right, my session is going to be 20 minutes according to the evidence and also that matches my subjective feeling. So, when you get to, you know, minute 16, 17, you're pretty much done. You can't take electronics in there because they will die. I'm going to start the timer for 20 minutes and I'm going to put it right here so I can see it so I know when to come out. 20 minutes has started. Let's jump in and not waste any time.
When I had done sauna before, it was something like 120 to 140, 145°, but 200 is just next level. When you go in, it's hot enough that actually if you put an egg white in there, the egg white would actually be hardened by the end.
So after this first sauna session I had a few problems arise. I did not know that 200° Fahrenheit was a fire-breathing dragon situation. The second thing that happened, it was so hot, especially on my scalp. I wondered, is this going to burn my hair off? So what I did for both is, for the nose, I learned that in the sauna I could do a 4-6 breathing exercise.
I like to do breathwork because there's nothing else to do in here, no electronics, no one to talk to. So, I try to do four seconds in, six seconds out, and just try to really calm myself.
And two, I found I could take an ice pack, put a towel on my head, and place it over my head to keep my scalp cool to make sure my scalp didn't get dried out with extensive exposure to that kind of dry heat.
This is like a pretty janky solution. I just kind of put together the various things I had. This is not like specially designed for saunas. This was in my freezer. So I'm like, okay.
We had several questions. The first was, would sauna stack with the benefits of exercise? Second, would it help in removing toxins from my body? I started this protocol knowing I had high levels of toxins in my body since the LA wildfires. And number three, we wanted to run an experiment on fertility, but we'll talk about that later. So, the plan was we would test all these biomarkers as a baseline and then come back to them after 21 sessions.
The main problem though is after a few days, I was wrecked. I'd wake up at night with these unbelievably terrifying cramps that hit my hamstrings and my calves so bad I'd jump out of bed. I'd try to walk it off. I just couldn't. I couldn't shake it. So, while the sauna protocol was going well, my sleep was getting worse.
So, with all this going on, I brought this up on our science call with Dr. Mike Malin and he had a hypothesis. By heating up your skin way faster than your core, Finnish sauna quickly flips your core-to-skin temperature gradient. This makes your body work on overdrive. The heart pumps blood up to 70% faster to get sweat to your skin to cool down. This gives cardiovascular effects similar to zone 1 or 2 cardio.
Sauna does make you sweat a lot, for example, between 0.6 and 1 liter per hour. So, of course, Dr. Mike suspected I was dehydrated. We tested using this Gatorade patch and it confirmed our suspicion. I was a salty sweater, and in each sauna session, I was losing 18 ounces of sweat and about 600 micrograms of sodium. And even though I was drinking enough to replace the water content I lost in sweat, I wasn't replenishing all the minerals I was losing, which caused the night cramps and other symptoms. So naturally, we increased the amount of electrolytes 50% before the sauna session and 50% immediately following.
Now, first, if you don't know if you're a salty sweater, you can test it. Second, if you are a salty sweater, make sure you're consuming the appropriate amount of electrolytes to make sure you do not become dehydrated.
By day seven, things were getting better because I had fewer cramps, but my sleep was still struggling. I've done a lot of therapies and a lot of treatments. That first week of sauna, I think, crashed me more than anything I did before. I suppose the funny thing about me is even though it was painful, I loved it. Am I weird?
After the first week, I was dying to get data. I love measurement. It was exciting to see several of my vascular markers had improved, including my central systolic blood pressure. My heart, brain, and all major organs were experiencing 5.83% less pressure.
Okay. So, why would sauna help blood pressure? Because of a process called heat-induced vasodilation. As your core body temperature rises in the sauna, your skin and peripheral blood vessels widen to help release heat, letting the same blood flow pass through with less force. This lowers the pressure inside your arteries, making them more flexible, and reduces strain on your heart and organs.
The fact that we saw this after seven sessions is pretty awesome actually, because it really suggests that the actual dose happens relatively quickly.
Now in week two, my relationship with sauna was really developing. Every day I really looked forward to the challenge, especially after a really hard workout. It was the sauna and me going alone. My cramps are gone. My sleep's getting slightly better. My vascular markers were improving, but I didn't know what was happening to my toxins. There was also another danger. Was sauna actually making toxins worse?
So, I wear cotton because I'm mindful of toxins. And when you get in there and it's very hot, I don't know what the interaction is between the clothing, the chemicals, and the heat and my skin.
We wondered, if we're going to sit in a 200° Fahrenheit box, what materials are used in the box, and are they potentially toxic? We also started evaluating what other things we could do to reduce toxins. Well, one obvious one, which is maybe not so obvious, is to not put water on the rocks. Water can have toxins like PFAS, forever chemicals. If you put them on the rocks, do they become airborne? So, we didn't put water on the rocks. Two is to make sure I had cotton clothing, not synthetics. That might be bad. And finally, to shower immediately following the sauna to make sure you're removing toxins from the skin.
But you may be asking, Bryan, why weren't you naked? I thought people sauna naked. That's because I was wearing an ice diaper. Don't laugh. Once I shared on social media I was wearing an ice diaper, I got a lot of questions. Now, in reviewing the scientific evidence, we saw that there was a potential of the heat actually hurting fertility markers pretty significantly. So, we took precautions to say we're going to put ice on the boys to prevent this harm. So, I went to my freezer and fortunately, I had a whole bunch of ice packs from a whole bunch of different therapies and I selected them trying to find the right match.
Here's the ice pack for the boys. So, I just slip in.
Human testes operate at 2 to 4° C cooler than core body temperature. Even a 2° C rise can derail spermatogenesis, the process of producing sperm, for 74 days, or a full cycle. I wasn't trying to get anyone pregnant, but Project Blueprint is about making the body as vital as possible in every organ, and that includes sperm health.
Now a question that came up is, what about other types of sauna, and specifically wet sauna? Dry Finnish saunas, as the name would suggest, are pretty dry. They have a relative humidity of 10 to 20%, whereas a normal room temperature has about 30 to 50% relative humidity, but that can be a lot lower in the winter. Wet saunas have roughly 100% relative humidity. That means they can't get above 115° Fahrenheit, 46° C, without causing you to burn or overheat. And as we know, most of the evidence for sauna's health benefits, especially long-term cardiovascular studies, focuses on Finnish sauna, where the combination of high heat and low humidity places the body under significant thermal and cardiovascular stress.
The other popular sauna option is infrared saunas. Because they heat up faster and generate less steam and condensation, they're way lower maintenance than dry or wet sauna, which makes them very popular with spas and wellness centers. But the problem is they can't get you much above 150° F, which doesn't match the existing studies on sauna benefits.
That's why I use a dry sauna. There's no real studies like that on an infrared.
So, we stuck with dry sauna. By week three, I'm feeling really good. No cramps, sleep is better, and I'm now in a rhythm. Also, it was time for a big batch of results. We had done enough sauna sessions to know that if we were going to see results, we'd see them by now.
First up was measuring toxins in my body, and man, we were shocked. There were significant reductions in the levels of toxins inside my body. Three went from being abnormally high to undetectable, and there was a huge drop across the board. This was beyond anything we'd expected. It was the best toxins result I'd ever received. As far as we could tell, this result was a pretty unique outcome according to the scientific literature. It seemed to suggest that sauna is potentially one of the best things you can do to detox your body.
After 23 sessions, my cardiovascular results also continued to improve. Central pressure readings were down significantly, putting even less pressure on my organs, and my resting heart rate, a major marker for recovery and fitness, had dropped by 4.4%.
And then came another twist. My fertility markers actually improved by 31% after 21 days. These were my best sperm health numbers to date and put me six times above the threshold for what's considered fertile by clinical standards. This made me wonder, should I bring this up on first dates?
A future question we want to ask: did my fertility biomarkers improve because of the combination of sauna improving blood flow and me using an ice pack? Or would an ice pack alone deliver similar results? There were a lot of people also wanting me to pair cold with the heat, but that's going to have to wait for another day because we wanted to see what sauna alone would do as a therapy.
So just a few weeks in, sauna was somehow improving my fertility, improving my blood vessels, and removing toxins from my body. But at this point, my sauna experiment hit a snag. I was traveling to Europe for 11 days, to Scandinavia, ironically, and I'd have no time to find a sauna and sit in it for 20 minutes every day.
So when I got back, we started sauna part two. The goal was to get to 48 total sessions. Here we had two main objectives. First, we wanted to see if the results would continue to improve, stay the same, or get worse. Would my body just get used to the stress and results, meaning I'd lose my cardiovascular gains? Second, we decided to stop icing my boys for 2 weeks to see what would happen. Basically, we decided to cook my boys at 200° F for science and your benefit. You're welcome.
I hit the 48-session mark and now it was time for the big reveal, the results. The bad news though was my fertility markers were demolished. I turned myself into a cautionary tale for every sauna enthusiast that has testicles. A 200° sauna with no ice protection led to a 50% reduction of my fertility markers across the board. So, boys, definitely ice your boys.
But the good news is my blood pressure and my vascular health improved a lot. My arteries became 25 to 50% more flexible, effectively de-aging them by about 10 years and giving me the vascular markers of a healthy 20-year-old. So we had evidence it is worth stacking sauna and exercise.
The second exciting result was a surge in VEGF. This is the signal your body says, "Hey, make more blood vessels." Think of blood vessels as roads carrying oxygen to every cell. VEGF is the helpful messenger calling for more roads, especially during repair or stress. That stress can increase VEGF because it tells the body grow more vessels. Heat makes your heart pump harder, pushing blood through your vessels. This helps keep your organs strong and slows down age-related decline. Previously, hyperbaric oxygen therapy had tripled my VEGF. But since doing sauna, I'd boosted it another 5x.
On top of that, these improvements to my cardiovascular health probably explain the 40% reduction in all-cause mortality that we saw in the Finnish studies for those that routinely do sauna. So, a lot of people ask the question, is it worth doing? And after seeing the results, I think the answer is yes.
Okay, so we've made it this far together, and you may be saying, I'm in, Bryan. Let's do it. How do I do it? For frequency, you want to target 3 to 5 sessions per week. The benefits seem to scale. For duration, target 15 to 20 minutes per session. For temperature, target 175 to 200° F, which is 80 to 93° C. Now, for the type of sauna, I would do dry over wet or infrared. You could also do it after exercise for stronger effects.
Now, for safety, you want to gradually build up to higher temperatures. If you want, you can even breathe through a damp cloth for airway protection. Stay hydrated with sufficient electrolytes. And men, be sure to cool the boys with non-toxic, BPA-free ice packs. To avoid toxins, wear cotton, bamboo, or go naked. You want to try and avoid synthetic towels, synthetic blends, and heavily treated fabrics. Don't put water on the rocks to avoid these toxins potentially getting in the air. Then, immediately following sauna, be sure to shower to wash off the
toxins. Now, in terms of the sauna you choose, just be sure they choose materials that are non-toxic. Best if you can check the air quality.
Now, you want to skip sauna if you're pregnant, if you have a heart condition, or any of the following conditions.
Now, if you don't have access to the sauna, your best alternative is exercise, which increases heat in your body. This is essentially free and achieves many of the same cardiovascular benefits, but doing both, as we saw, is ideal.
Oh, and good news, I restarted icing the boys and my fertility marker started to improve 30%. I expect a full recovery within a few more weeks.
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