You’ve been sitting in a small, 185°F room for ten minutes. You wipe sweat from your eyes as your heart beats at twice its normal rate. The person beside you groans while vigorously massaging their feet.
It sounds like a terrible time, but you’re loving it! You have beta-endorphins coursing through your blood, you feel great, plus you know sitting in the sauna has many benefits.
What benefits exactly? Today I plan to cover just that — including some interesting benefits that are likely unfamiliar to you. We’ll explore the sauna’s impact on chronic diseases, exercise performance, muscle maintenance, mood, and more. I’ll also review the science behind optimal sauna protocols, including proper hydration to replace sweat losses.
In other words, you’ll get a robust understanding of sauna benefits and how to make the most of your routine. To begin, let’s talk about what makes a sauna, a sauna: heat.
Why Is Heat Beneficial?
Heat exposure is a form of beneficial stress. It trains your body to handle heat and other stressors better in the future. For example, undergoing heat stress produces heat shock proteins. These molecules protect cells from damage, including the cellular dysfunction and protein misfolding associated with neurodegenerative disease.
The heat stress response influences many other bodily mechanisms too, but for simplicity’s sake, I suggest you consider the heat stress of the sauna to be a form of passive cardiovascular exercise. The physiological reactions — increased heart rate, cardiac output, blood volume, growth hormone, endorphins, and more — are similar and drive similar benefits.
I’m not saying the sauna should replace your exercise routine. But it can be a great “rest day” protocol, and a helpful cardiovascular exercise alternative for folks with mobility issues.
Dry heat saunas, steam rooms, and infrared saunas will all do the trick. However, it’s likely that dry heat saunas produce maximal benefits due to their higher temperatures (between 160–220°F). Steam rooms range between 110–120°F, and infrared saunas (which primarily heat your body using infrared radiation rather than the air) fall between 120–140°F.
Much like exercise, the health benefits of heat stress may trickle down into just about every part of your body — the heart, brain, metabolism, strength, endurance, mood, and more. Once you recover, you’re stronger, more resilient, and a wee bit harder to strangle on the jiu jitsu mat.
Getting into specifics now, let’s break the benefits of the sauna into 3 categories:
- Longevity benefits
- Physical activity benefits
- Other benefits
Longevity Benefits
I’ll lead with the research on longevity because it’s the most compelling to me. I think you’ll find it compelling too.
#1: Cardiovascular health
In 2015, Finnish researchers published results from the Kuopio Ischemic Heart Disease Risk Factor Study. They’d followed 2,315 middle-aged Finnish men for about 21 years, looking for a link between sauna use and cardiac outcomes.
They found one. Compared to men who used the sauna one time per week, frequent sauna users (4–7 sessions weekly) had a 63% lower risk of sudden cardiac death and a 40% lower risk of all-cause mortality. Those who used the sauna 2–3 times weekly had a level of risk in between the other two groups, suggesting the cardiovascular benefits increase with usage. The researchers controlled the data for other factors — like diet and exercise habits — that may confound the correlation.
Potential drivers of these cardiovascular benefits include:
- Better ventricular function
- Lower blood pressure
- Reduced cholesterol
- Reduced inflammation
That’s right! Similar benefits to aerobic exercise.
#2: Brain health
The Finnish researchers also found that men using the sauna 4–7 times weekly at 176°F had a 65% reduced risk of Alzheimer’s disease compared to once-weekly users. The authors think the sauna protects your brain in part because people who use the sauna regularly tend to have better blood vessel control (relaxation, constriction, and more). This helps reduce inflammation. They also mention that sauna may help maintain healthy blood pressure, which is a well-known risk factor for dementia.
Another explanation could be that heat stress increases blood flow to the brain. Enhanced cerebral blood flow improves cognition and prevents the accumulation of amyloid beta, a protein linked to Alzheimer’s. Heat also boosts the production of brain-derived neurotrophic factor (BDNF). More BDNF means more brain cell growth, including in areas associated with memory.
All-in-all, we need more research — but there seems to be many possible ways by which the heat stress of sauna may protect the brain.
#3: Metabolic health
Researchers have linked blood sugar regulation problems (insulin resistance) to many chronic diseases. Heat stress, it appears, may help.
In a 2006 study, three sessions of heat exposure weekly for 12 weeks decreased blood sugar and insulin levels in diabetic mice. In another study from 2001, two weeks of daily infrared sauna therapy reduced blood sugar in men with at least one heart disease risk factor.
Physical Activity Benefits
The sauna won’t get you banned from the Olympics, but it does appear to be a performance enhancer. Here’s a few ways the sauna can elevate your exercise regimen.
#4: Heat acclimation
Heat acclimation entails regular, controlled heat exposure — such as a sauna, hot bath, or cycling in a hot room. Repeated heat acclimation sessions lead to better subsequent performance in the heat. I’m talking about real physiological benefits: better core body temperature regulation, increased sweating, less sodium loss via sweat, enhanced fluid balance, improved glycogen efficiency, and cardiovascular stability.
A 2020 study found that spending time in the sauna post-exercise improved heat adaptation in runners. One group of participants sat in the sauna for 30 minutes after exercising (three times per week, for three weeks). The other group did not have sauna sessions. Following this protocol, the sauna group had better metrics than non-sauna goers: lower skin temperatures by 1.4°F, lower core body temperatures by 0.36°F, and lower heart rates by 11 beats per minute.
Another study from 2017 had nine women wear a sauna suit (stylish!) for 20 minutes before a heated workout. Following this five-day heat acclimation protocol, the women had lower core body temperatures by 0.5°F and lower peak heart rates by 12 beats per minute compared to when they “chilled” in sports bras and shorts before training.
#5: Endurance
Endurance is a byproduct of the sauna’s cardio benefits. In a small crossover study, six trained runners were able to run for 32% longer after three weeks of using the sauna post-exercise.
Researchers believe the benefits were driven by increased blood volume and red blood cell counts. More red blood cells mean more oxygen to tissues, which is useful when you’re going for a personal record.
#6: Muscle maintenance and recovery
As we age, it gets harder to maintain muscle. Heat stress may preserve muscle by increasing heat-shock proteins and boosting growth hormone. One study found that ten days of local heat treatment reduced muscle atrophy by 37% in 23 immobilized adults.
Other research suggests infrared sauna use improves muscle soreness and perceived recovery after strength training. More objective markers like heart rate variability were unaffected. The bottom line is that we need better science on saunas’ strength and muscle benefits — but no doubt, it’s an interesting frontier to explore further.
Other Benefits
Lastly, let’s dig into how the sauna impacts mood and growth hormone levels, as well as add some color to an often-touted benefit: detoxification.
#7: Mental health
Heat stress triggers a massive release of feel-good chemicals called beta-endorphins. Unsurprisingly, heat has shown some degree of benefit in treating mood disorders. In one study, four weeks of sauna use improved appetite and other symptoms in 28 people with mild depression. In another, a single session of core body temperature elevation to 101.3°F had anti-depressive effects that persisted for six weeks in 30 adults with depression.
#8: Growth hormone
Sauna usage appears to increase growth hormone. Since it helps with both longevity and physical activity, I decided to give it a special callout here.
A Finnish study of eight healthy men found that:
- Two 20-minute sessions at 176°F separated by 30 minutes of cooling off caused a 2x increase in growth hormone levels.
- Two 15-minute sessions at 212°F separated by 30 minutes of cooling off caused a 5x increase in growth hormone levels.
Other research suggests combining sauna with exercise has a synergistic effect on growth hormone production.
#9: Detoxification
“I love to sweat. It just feels like I’m getting all the bad toxins out.”
Say this in a gym, and most everyone will excitedly nod their heads in agreement. And while it’s true that scientists have found BPA, heavy metals, pesticides, and other toxins in sweat, it’s unclear if sweating is actually “detoxing” these compounds.
For example, the standard method of sweat analysis (scraping sweat from skin) also picks up sebum, a non-sweat secretion more likely to contain toxins like BPA. Not to mention, steam from the sauna can condensate on one’s skin, introducing foreign contaminants.
This comprehensive review outlines several known issues with sweat collection methods, which may play a role in why certain compounds (like ethanol, heavy metals, pesticides, BPA, phthalate, and more) are found in sweat. The takeaway is that there is not enough evidence to say whether sweat actually detoxifies the body.
What’s the Optimal Sauna Protocol?
Right about now, you may be all-in on starting a sauna routine. But what’s the optimal regimen to maximize sauna benefits?
I’ll wager that “optimal” depends on your unique physiology and circ*mstances. But data from the Kuopio Ischemic Heart Disease Risk Factor Study suggests that using the sauna 4–7 times per week, heated to at least 174°F, for at least 20 minutes is an awesome goal to work up to. Subjects following this routine experienced benefits related to heart disease, Alzheimer’s, and longevity overall.
Short and less frequent sessions seem to reduce these effects, but hotter temperatures may make up for shorter durations. For benefits related to endurance, growth hormone release, and mood, hotter temperatures may also be better up to a point. I suggest healthy folks cap sauna temperature around 212°F. The bottom line is that if you feel too hot (or especially if you feel unwell), it’s worth backing off a little bit. You don’t need to burn your nose hairs to benefit from sauna use — you’ll still benefit from one or two sauna sessions per week.
What about infrared saunas?
Recall infrared saunas? They heat your body using infrared radiation (versus simply heating the air around you) and typically max out at lower temps, around 140°F. There’s less science on infrared compared to traditional saunas, but evidence suggests they also help with cardiovascular and metabolic health. You get similar heat stress benefits, but probably to a lesser extent due to the lower temperatures.
Does sauna use have risks?
A lesser-known consequence of frequent sauna use (which can also result from other heat exposure like hot baths and hot tubs) is reduced male fertility. So if you’re trying to conceive, it may be wise to lay off the sauna for a while. Don’t worry, sperm counts return to baseline within 6 months.
Common-sense risks of sauna include the high heat levels themselves, or staying inside too long. The solution is to listen to your body. Take a break if you feel dizzy, faint, or lightheaded — heat exhaustion is not a good time. And, to my next point, be sure to replace the fluids and electrolytes lost in sweat to avoid dehydration.
Hydrating for the Sauna
Predictably enough, sweating in the sauna increases hydration needs. The more you sweat, the more fluids and electrolytes you must replace to return to equilibrium.
Let’s look at a few studies that reported sauna-induced sweat losses:
- 12 adults lost 0.3–1.4% of their body mass during a 30-minute session (1% body mass loss for a 180-pound adult is about 0.8 liters of fluid).
- 10 men lost about 2 kg of body weight (2 liters of fluid) after six 15-minute sessions separated by 5-minute breaks.
- 30 men lost 1.8 kg (1.8 liters of fluid) of body weight after three 20-minute sessions.
Broadly speaking, the research suggests people lose up to a liter of sweat every 20–30 minutes in the sauna, but your mileage may vary. Use thirst to calibrate your water intake post-sauna, and replace electrolytes (especially sodium) with fluids to prevent electrolyte deficiency.
An evidence-based tip is to include 1 gram of sodium per liter of water. This creates a rehydration solution that is close to athletes’ average sweat sodium concentration. It’s no coincidence that each serving of LMNT contains precisely 1 gram of sodium. Makes things easy!
With your hydration protocol handled, you’ll enjoy the sauna even more. You’ll get the health benefits without feeling like a sun-dried tomato. And if your fellow sauna-goers get on your nerves (why does he keep grunting and slapping his thighs?), well… at least you’re only in there for a few more minutes.
