Unlocking the Secrets of Sauna Therapy: A Holistic Approach to Wellness
Updated: Aug 26
Created by Christopher Caffrey, ACNP, PMHNP, Functional Medicine-trained
August 11th, 2025
Key Takeaways:
Sauna may support cardiovascular health. Regular heat exposure can temporarily increase heart rate, improve circulation, and may support healthier blood pressure and blood-vessel function over time.
Sauna is not a replacement for exercise. It can raise your heart rate, but it does not build muscle, strengthen bone, or provide the full metabolic benefits of physical activity.
“Detox” and fat-loss claims are overstated. Sweating can remove small amounts of certain substances, but your liver, kidneys, gut, and lungs do most of the body's detoxification. Any immediate weight loss after sauna is mostly water, not body fat.
Sauna may help with relaxation, recovery, and sleep. Many people feel calmer and sleep better after sauna, especially when it is used as part of a consistent evening or recovery routine.
The right dose depends on the person. Hydration, medications, blood pressure, kidney function, pregnancy, fertility goals, exercise load, and overall health all matter. The goal is not to tolerate the most heat—it is to use sauna in a way that leaves you feeling restored, not depleted.
A sauna is one of the few wellness practices where you can sit perfectly still, do absolutely nothing, and watch your heart rate climb.
Naturally, the wellness world took this and ran with it. Sauna has been called cardio, detoxification, a fat-loss tool, a sleep treatment, a longevity hack, and occasionally something just short of a cedar-paneled fountain of youth.
The reality is less dramatic, but probably more useful.
Sauna exposes your body to a temporary, controlled dose of heat stress. Your heart works a little harder, blood vessels near the skin open, circulation changes, and sweating increases as your body tries to keep its internal temperature stable. For many people, the experience is also deeply relaxing.
From a functional medicine perspective, I find sauna interesting for a different reason. It affects several systems at once: cardiovascular function, circulation, temperature regulation, hydration, stress response, and potentially sleep and recovery. It is a good example of how the body rarely operates in isolated compartments.
But there is an important principle here:
A useful stressor can become an unhealthy stressor when the dose exceeds your ability to recover from it.
Exercise works the same way. So does fasting. More is not always better.
Used intelligently, sauna may be a valuable addition to a healthy lifestyle. Used recklessly—or sold as a cure for everything—it becomes just another wellness fad.
What Actually Happens When You Get Hot?
Your body does not care that the room smells pleasantly of cedar. It recognizes one thing: heat.
Your internal temperature is tightly regulated, so when your surroundings become very hot, your body immediately begins trying to cool itself. Blood vessels near the skin widen so that warm blood can move closer to the surface. Your heart begins pumping faster to keep that blood circulating, and sweat production increases so evaporation can help release heat. This is why your skin becomes flushed and your pulse rises even though you are sitting still.
In one study of roughly 100 adults, a 30-minute sauna session increased average heart rate from about 65 to 81 beats per minute. Blood pressure temporarily decreased, and the arteries became somewhat more flexible.[1] When researchers talk about arterial stiffness, they are simply describing how easily your arteries expand and contract. Generally, healthier arteries are better able to respond to changes in blood flow.
This cardiovascular response is one reason sauna is sometimes compared with exercise. There is some truth to that comparison. Both exercise and heat can raise heart rate, increase circulation, and challenge your body's ability to regulate temperature.
But the comparison has limits.
Sitting in a sauna does not strengthen your muscles, load your bones, improve balance, build athletic skill, or reproduce everything that happens metabolically when you exercise. Your heart beating faster does not automatically make something equivalent to a workout.
A revving engine is not the same as a car traveling down the road.
Think of sauna as a complement to exercise—not a substitute for it.
The Most Interesting Evidence Is Cardiovascular
The strongest case for regular sauna use involves the heart and blood vessels.
Much of the research comes from Finland, where sauna is not considered an exotic health intervention. It is simply part of normal life. That has allowed researchers to study people who have used saunas regularly for many years.
One of the most frequently cited studies followed 2,315 middle-aged Finnish men for about 21 years. Men who reported using a sauna four to seven times per week had substantially lower rates of sudden cardiac death and fatal cardiovascular disease than men who used one sauna per week.[2]
Another Finnish study following 1,628 men and women found that people using a sauna four to seven times per week had a lower rate of stroke than those using one weekly session.[3] Those findings are impressive.
But there is an important catch. These were observational studies. That means researchers watched what happened to people over time rather than randomly assigning one group to sauna frequently and another group not to sauna.
This distinction matters because frequent sauna users might differ in other ways. They may exercise more, have better social connections, drink differently, manage stress better, or generally pay more attention to their health.
So the studies tell us:
Frequent sauna use was associated with better cardiovascular outcomes.
They do not prove:
Sauna alone caused those outcomes.
There is some experimental research supporting the possibility of a real cardiovascular benefit. In one eight-week trial, adults with cardiovascular risk factors were assigned to exercise alone or exercise followed by a short sauna session. The exercise-plus-sauna group showed greater improvements in blood pressure, cholesterol, and cardiorespiratory fitness—which simply means how effectively the heart and lungs can supply oxygen to the body during physical activity.[4]
Still, the overall research is not completely settled. A 2025 review that combined results from 20 randomized trials found that many cardiovascular and metabolic improvements were not statistically significant when the studies were analyzed together, although some groups appeared to experience modest improvements in blood pressure.[5]
So where does that leave us?
Somewhere much more reasonable than either “sauna does nothing” or “sauna prevents heart attacks.”
Regular heat exposure appears promising, particularly for cardiovascular health, but sauna belongs alongside exercise, good nutrition, adequate sleep, blood-pressure management, and appropriate medical treatment.
It does not replace them.
Sauna as a Controlled Stressor
This is where I think the functional medicine perspective becomes especially useful.
Health is not simply the absence of stress. A healthy body needs the ability to respond to stress and then recover from it.
Exercise is a stress. Your muscles experience strain, energy demand increases, and your cardiovascular system works harder. Then, provided that you eat, sleep, and recover appropriately, the body adapts.
Sauna creates a different kind of challenge. Your body has to move blood toward the skin, regulate temperature, maintain blood pressure, and manage fluid loss. In the right person and at the right dose, repeated exposure may help the body become more accustomed to handling that challenge.
The mistake is assuming that if some stress is beneficial, extreme stress must be even better. It isn't.
Someone who is well rested, hydrated, eating adequately, and generally healthy may tolerate heat very differently from someone who is dehydrated, sleep deprived, ill, taking certain medications, recovering from a marathon, or struggling with low blood pressure.
The right question is not:
“How much heat can I tolerate?”
It is:
“What dose of heat leaves my body feeling better rather than depleted?”
Let's Talk About “Detox”
This may be the most abused sauna claim. Yes, sweat can contain small amounts of environmental chemicals and certain metals. No, that does not automatically mean sauna is the most effective medical detoxification treatment.
One commonly cited study examined BPA, a chemical historically used in some plastics and food-container materials. Researchers were able to detect BPA in sweat.[6] Interesting finding—but the study did not show that sauna meaningfully reduced the total amount of BPA stored in the body or that sweating improved anyone's health.
Research has also detected metals such as arsenic, cadmium, lead, and mercury in sweat.[7]
Again, finding something in sweat and proving meaningful detoxification are two different things.
If I find salt in seawater, that tells me salt is present. It does not tell me how much salt exists in the entire ocean.
The same problem occurs when someone points out that a toxin is more concentrated in sweat than in blood. Concentration is not the same as total amount removed.
Your primary detoxification systems are much less glamorous: your liver, kidneys, gastrointestinal tract, and lungs. They continuously process, transform, filter, and eliminate substances from the body. Sweating is primarily your cooling system.
Could sweat represent one smaller route through which certain substances leave the body? Yes.
Is that the same as proving that routine sauna treats heavy-metal toxicity or removes meaningful quantities of environmental toxins? No.
If someone has a genuine toxic exposure, the answer is identifying the exposure and obtaining appropriate medical evaluation—not trying to sweat harder.
What About Weight Loss?
You may weigh less immediately after a sauna. Unfortunately, your fat cells have not packed their bags and moved out.'
The drop on the scale is primarily water loss from sweating. Once you rehydrate, much of that weight returns.
Your heart rate may also become surprisingly high during a sauna session, which can make fitness watches report impressive calorie expenditure. Those estimates should be viewed cautiously. Your heart is beating faster largely because your body is trying to manage heat and move blood toward the skin, not because your muscles are performing the physical work of running or lifting.
Sauna may still fit nicely into a weight-management program. It may help you relax after training, make recovery rituals more enjoyable, and encourage consistency with an overall healthy routine.
But sauna itself is not a reliable fat-loss strategy. If you lose two pounds during a sauna session, most of those pounds are probably now in the towel.
Rehydrate. Don't celebrate the weigh-in.
Sleep, Stress, and the Nervous System
This is one of the areas where patient experience is often ahead of the research.
Many people simply feel better after sauna. They describe feeling calmer, physically loose, mentally quieter, and more ready to sleep.
In one survey of 482 regular sauna users, more than 80% reported that sauna helped their sleep.[8] That is noteworthy, but it does not prove sauna improves sleep for everyone. The study surveyed people who already chose to use saunas, so it is not surprising that many of them liked the experience.
There is, however, a plausible reason heat might help. One of the body's natural signals before sleep is a gradual decrease in core temperature. Heating the skin beforehand increases blood flow toward the body's surface. After you leave the heat, this may help your body release warmth more efficiently.
Research on warm baths and showers suggests that heating the body roughly one to two hours before bed may help people fall asleep more quickly and improve certain measures of sleep.[9] A bath and a sauna are obviously not identical, but the general temperature-regulation mechanism is interesting.
Practically, I would treat evening sauna as an experiment. If you finish a session, cool down, rehydrate, and notice that you become relaxed and sleepy, great. If it leaves you overheated, thirsty, stimulated, or waking several times to urinate because you drank a gallon of water afterward, move it earlier. Your response matters more than an internet protocol.
Stress relief may actually be one of sauna's most immediate benefits. Spending 15 or 20 minutes somewhere warm and quiet without emails, news, work demands, or your phone constantly demanding attention is not physiologically trivial. You do not need a complicated explanation involving “cortisol optimization” to justify that.
Heat itself can temporarily activate the body's stress response. So the claim that sauna simply “lowers cortisol” is too simplistic. What matters may be the entire sequence: a short challenge, followed by cooling, relaxation, and recovery.
Can Sauna Help Mood?
Possibly, (probably) but this is an early area of research. A small randomized study found improvements in depressive symptoms after whole-body hyperthermia, which is a medically supervised treatment that deliberately raises body temperature.[10]
That sounds similar to sauna, but it was not the same thing. Participants underwent much longer and more carefully controlled heating than someone sitting in a home sauna for 15 minutes. So I would not tell a patient that sauna treats depression or anxiety; but you will probably feel fantastic after a session.
I would say that heat and mood are being studied, and many people subjectively find sauna calming. If sauna improves your stress level, relaxation, sleep, or sense of well-being, those effects still matter—even if we cannot reduce them to a single laboratory marker.
Traditional, Steam, or Infrared?
There is no universally “best” sauna. Traditional Finnish saunas use relatively high temperatures and fairly dry air, with occasional bursts of steam when water is added to hot stones. Most of the impressive long-term cardiovascular studies were conducted in Finnish sauna users, so traditional sauna currently has the strongest historical research base.[2,3] That does not necessarily mean traditional sauna is superior. It means it has been studied more.
Steam rooms use lower temperatures but much higher humidity. Because sweat cannot evaporate as easily in humid air, they can sometimes feel hotter than the thermometer suggests.
Infrared saunas use radiant energy to heat the body while keeping the surrounding air at a lower temperature. Some people find this more comfortable. Research exists, but the evidence base is smaller and includes many different devices and protocols.
This is another area where marketing tends to get ahead of science.
The cardiovascular results from Finnish sauna research cannot automatically be transferred to every infrared unit on the market.
For most people, the best sauna is probably the one they can tolerate comfortably, access regularly, and use safely. Consistency beats theoretical perfection.
How I Would Approach Sauna Practically
There is no scientifically established magic temperature or perfect number of minutes that unlocks longevity. However, 20 mins in 180 degree dry sauna seems to hit a wellness mark.
Traditional Finnish saunas often run somewhere around 158–212°F, but temperature alone does not determine how stressful the experience will be. Humidity, where you sit in the sauna, your hydration, your level of acclimation, medications, and your health all matter.[2,11]
A reasonable starting approach for a generally healthy adult is to begin with about 5–10 minutes at a comfortable temperature. If you consistently feel well during and after sessions, gradually working toward roughly 15–20 minutes is reasonable.
Two or three sessions per week can be a practical starting habit. That is not a scientifically proven disease-prevention dose; it is simply a sustainable place to begin.
Arrive hydrated. Replace the fluid you lose. If you have exercised heavily beforehand or tend to sweat substantially, food and electrolytes may also be appropriate.
And do not combine alcohol and sauna. Alcohol, dehydration, heat, and impaired judgment have no reason to become teammates.
Most importantly, listen to your body. Dizziness, nausea, unusual weakness, severe headache, chest pain, significant shortness of breath, palpitations, or confusion are not signs that you are “pushing through the adaptation.” They are signs to get out.
And the Cold Plunge?
You do not need to launch yourself into ice water simply because you used a sauna.
Hot-to-cold exposure can feel invigorating, and some people enjoy it, but the sudden shift creates another cardiovascular challenge. That may not be appropriate for someone with certain heart conditions or unstable blood pressure.
A normal shower and a gradual cooldown are perfectly respectable.
Functional medicine should not become competitive suffering. The goal is to create an intervention that your body can recover from and that you can repeat consistently.
Who Should Be More Cautious?
Healthy adults generally tolerate sauna well, but personal medical context matters.
Speak with a clinician before beginning regular sauna use if you are pregnant; have unstable cardiovascular disease; experience recurrent fainting; have very low or poorly controlled blood pressure; have kidney disease; have difficulty sensing or regulating heat; take medications that significantly affect blood pressure, hydration, or sweating; or have been instructed to limit your fluid intake.[11,12]
Avoid sauna when you are acutely ill or feverish. Your body is already dealing with heat and physiological stress; adding more is not necessarily productive.
Men actively trying to conceive should also understand that repeated high-heat exposure may temporarily affect sperm production. In one small study, twice-weekly sauna use for three months reduced sperm count and movement, with recovery after the heat exposure stopped.[13] An occasional sauna session is not a reason to panic, but frequent high heat may be worth limiting when fertility is already a concern.
The Functional Medicine View
I do not think sauna needs exaggerated detox claims or longevity promises to earn a place in a wellness plan. Its value may actually come from something more ordinary.
It challenges circulation. It creates a manageable dose of heat stress. It can become a reliable transition from activity to recovery. It may support cardiovascular health. It may help some people sleep better. And perhaps most importantly, it gives people a reason to stop moving for 15 minutes.
That last benefit is probably underestimated.
But sauna also illustrates an important principle of functional medicine: the intervention cannot be separated from the person receiving it.
The same 20-minute sauna that leaves one person relaxed and restored may leave another dehydrated, dizzy, and exhausted.
Your sleep matters. Your hydration matters. Your medications matter. Your blood pressure matters. Your exercise load matters. Your health history matters.
The goal is not simply to add another wellness tool. The goal is to understand whether that tool moves your physiology in a healthier direction.
The Bottom Line
Sauna deserves a place in the conversation without being turned into a miracle machine.
The most compelling research involves cardiovascular health, although the strongest long-term studies show association rather than absolute proof of cause and effect. Relaxation and sleep benefits are plausible and commonly reported. Research into mood is interesting but still preliminary.
The evidence for meaningful fat loss or medical “detoxification” is much weaker.
So use sauna for what it appears to be good at: a repeatable form of controlled heat exposure that may support cardiovascular health, relaxation, recovery, and an overall healthy lifestyle.
Keep exercising. Keep eating well. Keep sleeping. Keep managing your blood pressure. Keep taking medications you actually need. Keep drinking water.
And if sauna makes you feel better and you tolerate it well, keep doing that too.
The goal is not to survive more heat. The goal is to become healthier outside the sauna.
References
Laukkanen T, Kunutsor SK, Zaccardi F, et al. “Acute Effects of Sauna Bathing on Cardiovascular Function.” Journal of Human Hypertension. 2018;32(2):129–138.
Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. “Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events.” JAMA Internal Medicine. 2015;175(4):542–548.
Kunutsor SK, Khan H, Zaccardi F, et al. “Sauna Bathing Reduces the Risk of Stroke in Finnish Men and Women: A Prospective Cohort Study.” Neurology. 2018;90(22).
Lee E, Kolunsarka I, Kostensalo J, et al. “Effects of Regular Sauna Bathing in Conjunction With Exercise on Cardiovascular Function: A Multi-Arm Randomized Controlled Trial.” American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2022;323(3).
Hamaya R, Joyama Y, Miyata T, et al. “Non-Acute Effects of Passive Heating Interventions on Cardiometabolic Risk and Vascular Health: Systematic Review and Meta-Analysis of Randomized Controlled Trials.” American Journal of Preventive Cardiology. 2025;23:101082.
Genuis SJ, Beesoon S, Birkholz D, Lobo RA. “Human Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) Study.” Journal of Environmental and Public Health. 2012;2012:185731.
Sears ME, Kerr KJ, Bray RI. “Arsenic, Cadmium, Lead, and Mercury in Sweat: A Systematic Review.” Journal of Environmental and Public Health. 2012;2012:184745.
Hussain JN, Greaves RF, Cohen MM. “A Hot Topic for Health: Results of the Global Sauna Survey.” Complementary Therapies in Medicine. 2019;44:223–234.
Haghayegh S, Khoshnevis S, Smolensky MH, Diller KR, Castriotta RJ. “Before-Bedtime Passive Body Heating by Warm Shower or Bath to Improve Sleep: A Systematic Review and Meta-Analysis.” Sleep Medicine Reviews. 2019;46:124–135.
Janssen CW, Lowry CA, Mehl MR, et al. “Whole-Body Hyperthermia for the Treatment of Major Depressive Disorder: A Randomized Clinical Trial.” JAMA Psychiatry. 2016;73(8):789–795.
Hannuksela ML, Ellahham S. “Benefits and Risks of Sauna Bathing.” The American Journal of Medicine. 2001;110(2):118–126.
Organization of Teratology Information Specialists. “Fever/Hyperthermia.” MotherToBaby. Updated February 1, 2025.
Garolla A, Torino M, Sartini B, et al. “Seminal and Molecular Evidence That Sauna Exposure Affects Human Spermatogenesis.” Human Reproduction. 2013;28(4):877–885.
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