How Long and How Hot Should Your Sauna Be? Heat Therapy Basics Based on Science
Sauna: how long and what temperature?
A sauna is a small room or house designed as a place to experience dry or wet heat sessions. Saunas can be divided into two main types: conventional saunas that use hot rocks or steam to heat the air, and infrared saunas that use lamps to heat the body directly.
Saunas are very beneficial for overall health, as they can help improve circulation, reduce stress, and relieve pain. They are also great for detoxification, as the heat helps to sweat out toxins from the body.
Researchers from the University of Eastern Finland tracked 2,300 middle-aged men over 20 years and found that those who used a sauna often lived longer. Throughout the study, 49% of the men who used a sauna once a week died, compared to only 31% of those who used it four to seven times per week.
Frequent visits to the sauna have been associated with lower mortality rates from all causes, including cardiovascular disease and cancer.
So how long and how hot should your sauna be?
Before answering that question, it is important to understand the difference between traditional and infrared saunas. Traditional saunas heat the air to high temperatures using rocks or steam. The hot air then heats your body indirectly.
On the other hand, infrared saunas use infrared lamps to heat your body directly. Infrared waves are a type of electromagnetic radiation that penetrates deep into your tissues, providing a host of health benefits. Many people also opt for infrared sauna blankets as a more budget way to achieve heat therapy at-home.
Regardless of the heat source, it is important to understand how long you should spend in the sauna and how hot your sauna should be.
How Long To Spend In a Sauna and How Hot Should Your Sauna Be?
While there is no single answer to this question (as everyone's heat tolerance is different) there are some general guidelines that can be followed. The average person can tolerate about 10-20 minutes in a traditional sauna at a temperature between 160-180 degrees Fahrenheit or 70-90 degrees Celsius.
Although the recommended usage of the American College of Sports Medicine for sauna is no longer than 20 minutes, recent research suggests that a better figure to aim for is 57 minutes of heat exposure in a sauna per week spread over 3-4 sessions, for the minimum effective dose.
Staying no longer than 20 minutes in a sauna at once is important, as extended periods of heat exposure can lead to dehydration and potentially cause heat stroke.
Ideally, spending 15-20 minutes in a traditional sauna at 70-90 degrees C is a good range to produce the desired benefits of sauna use. While 160-180 degrees Fahrenheit or 70-90 degrees Celsius is the recommended temperature range, some people may find that they can tolerate hotter temperatures for shorter periods. It is important to listen to your body and not push yourself too hard. If you start feeling nauseous, lightheaded, or dizzy, it is time to get out of the sauna.
With an infrared sauna, the ideal temperature range is generally between 120-140 degrees Fahrenheit. Typical sessions last between 20-45 minutes. As with a traditional sauna, it is important to listen to your body and not push yourself too hard. Because infrared saunas run at a lower temperature, it is beneficial to stay in longer than you would in a traditional sauna as the body will heat up slower
Whatever you choose, all saunas serve the same purpose: to produce "heat stress".
What is Heat Stress?
Heat stress is the result of your body being exposed to temperatures higher than its internal temperature. This increases heart rate and blood flow as your body tries to cool itself down. This stress, also referred to as “Eustress”, is a useful and beneficial stress that has positive impacts on metabolism, skin health, mental health, relaxation and positive mood, body composition and weight loss, heat acclimation, and perceived exertion or exercise threshold.
The body experiences stress from high temperatures, setting off a thermoregulatory reaction to reestablish equilibrium. For instance, the hypothalamus responds to increasing heat by signalling the blood vessels to widen when it is warm outside or in a heated environment.
Warm blood, salts, and fluids may now travel to the skin while others evaporate as the blood cools. To maximise cooling through sweating, between 50 and 70% of blood flow is diverted from the body's centre to the skin's surface.
Deliberately producing this heat stress has several benefits for the body, including injury recovery, reduced stress, and relief from pain. This hormetic stressor can make us more resilient in mind and body when it is practiced habitually but without over-exposure. Heat stress most definitely has a point of diminishing return and should be practiced safely to avoid issues like heat stroke, dehydration and organ failure or death.
The sweet spot of hormetic stress from sauna
Contrast Therapy
Another option is contrast therapy. This involves alternating between hot and cold temperatures. This can be done either in a sauna or shower. A common protocol for contrast therapy is to spend one minute in a sauna or hot shower followed by 1-2 minutes in a cold shower. This cycle is repeated 3-5 times.
Danish scientist Dr Susanna Søberg recently conducted a study on the effects of contrast therapy on the human body. BAT (brown adipose tissue) was found to be increased in those who used contrast therapy.
BAT is important as it helps to burn calories and fat. Increased BAT in adult human thermoregulation suggests both heat and cold acclimation improve whole-body function and capacity.
It also suggests that contrast therapy can help you burn more calories and fat. If you are looking to lose weight, this is a great way to do it. Athletes that are cutting or trying to lean out also use contrast therapy as a way to help them hit their target.
It is also worth noting that Soeberg also found that for the greatest metabolic benefit of contrast therapy, it is best to finish on the cold plunge and not the sauna, despite how tempting it is to finish with heat. When you allow the body to cool itself down, in an open posture with no use of towel to dry off or clothing to warm up, you are achieving the greatest activation of brown fat as possible.
Benefits of Saunas
Several clinical trials have demonstrated that continuous, low-level heat therapy provides early pain relief and improves muscular strength in patients with lower back pain.
See best infrared sauna for home
A sauna session can also help to improve circulation and relieve muscle tension. The heat dilates blood vessels and increases blood flow, which can help to reduce inflammation. This is why heat therapy is often used to treat conditions such as arthritis or fibromyalgia.
Heat therapy has also been shown to help treat chronic stress and anxiety. One study found that regular sauna use was associated with a lower risk of death from all causes, including cardiovascular disease and cancer.
Other benefits:
Improved sleep quality
Reduced stress levels
Cognitive and brain benefits through boosting BNDF
Increased relaxation
Alleviation of stiffness and pain
Detoxification through sweating
Improved circulation
Heat acclimation
Weight loss
That said, not all users will experience each benefit and a sauna should not be used as a replacement for medical treatment.
Tips for using a sauna
Due to the nature of saunas, when you use a sauna at a gym, wellness space or recovery centre, there is sauna etiquette to adhere to. I have seen countless people at Bondi Icebergs Sauna and other busy saunas in Sydney be berated and yelled at for not knowing basic rules for using a sauna, particularly a busy public one.
When going to a sauna, theres a few things you can do to make your sauna session a good experience for yourself and for everyone else.
Local Rules - Check the local rules and expectations of the sauna you are going to - different saunas have different dress codes and some allow nudity while others don’t. Some saunas seperate male and female sauna use and some spaces practice things like Womens Only Nights, so it is important to know where you are going and how they operate.
Pre-Sauna Rinse - Always rinse off in a shower before entering a sauna as you want to be as clean as possible to keep the sauna hygienic for yourself and everyone else.
Take a towel - Ideally, many saunas expect you to take a towel to place down under your body to minimise the amount of sweat you drop onto to sauna surfaces and reduce the transfer of bodily fluids despite this being an inevitable part of using a sauna.
Share the space - Often saunas have multiple levels to them. The upper levels are hotter as the heat rises to the top of the sauna and most people like to take up the upper levels first. If the sauna is busy, know your place in the line and always offer up the space to others if you entered after.
Enter and exit swiftly - There is nothing worse than a busy sauna that constantly loses heat from people walking in and out of the space. To minimise heat lost from walking in and out of the sauna, it is very important to get in or leave the sauna as fast as possible without opening the door too much to the outside elements. This will ensure the sauna stays as hot as possible.
Hydrate - The amount of sweat you produce to cool the body during a 20 minute sauna session can be intense even if you are acclimatised to heat. As you lose a lot of important electrolytes from sweating, it is important to stay hydrated constantly in a sauna. I like to take in a 2L bottle with some salt or a Hydralyte or something similar.
Best Sauna Protocols
As sauna use mimics moderate intensity cardiovascular exercise, when you sweat regularly in a hot sauna, infrared sauna, steam room or sauna blanket, you are getting many of the same physiological responses and effects of a workout. For best sauna protocols, there are a few that I follow for cardiovascular health, human growth hormone boost and general heat therapy for health and immune benefits.
Protocol 1 - Single session
When you use a sauna habitually, you are literally increasing the longevity of your life, according to research. Using the sauna just one session per week improves cardiovascular health, promotes blood flow, can improve auto-immune conditions and boost mood.
With this protocol, you can stay in the sauna from 5-20 minutes depending on the temperature. I generally aim for 15-20 minutes at 80-90 degrees celsius for my single use session protocol and generally use this one directly after a strength based workout where I am aiming to relax the muscles and promote blood flow/vasodilation for healing. It is beneficial to use this protocol every day of the week if you have access to a sauna or sauna blanket at home or have the budget to do so at a gym or wellness space.
Protocol 2 - Growth Hormone
Sauna has been shown to increase human growth hormone by 15 x in a study. Be aware, this protocol is a little more challenging and requires a bit more time and dedication. To get the most out of this protocol, it is also beneficial to be in a fasted state. This protocol should be worked up to and is probably not ideal for someone who is new to sauna as it entails about an hour of time in the sauna.
Human growth hormone is produced during sleep and is essential for recovery, promoting muscle repair and growth, is involved in bone strengthening and density, essential for tissue repair and loads of other functions. To increase growth hormone using sauna, stay in the sauna for 30 minutes anywhere from 70-90 degrees celsius, followed by 5 minutes rest and cool down, before another 30 minutes back in the sauna.
Protocol 3 - Contrast
The latest research from Susanna Soeberg suggest a synergistic effect of engaging in cold plunge and sauna together, also known as contrast therapy. By combining heat and cold, the shock proteins and norepinephrine release creates a cascade of beneficial effects on recovery, mood and sleep. I have recorded roughly 6% improvement in weekly recovery score and roughly 20 minutes more sleep per night using the Whoop to track my data when using contrast therapy.
My ideal contrast therapy protocol is 15 minutes in the sauna at 80-90 degrees celsius, followed by 2-3 minute ice bath at 6-10 degrees celsius, repeated for 2 -3 rounds.
With any of these protocols, be sure to take it slow and do not over exert yourself, particularly in the sauna as it is easy to become dehydrated and suffer heat stroke. For cold plunge, many experts stress the importance of using your breath as timing rather than a clock, as you are more able to tune into the body instead of fighting against a time limit.
Conclusion
Whether you are using traditional sauna or infrared sauna, the heat stress is the main thing to aim for as it is what provides the hormetic or adaptive response that improves recovery time, increases heat acclimation, reduces stress, improves mood and speeds up healing from injury. While traditional heat therapy uses dry heat and should be aimed at 10-20 minutes of use between 70-90 degrees C, infrared sauna uses a lower radiant heat which you should aim for 30-60 minutes at 60-75 degrees C.
Both forms of therapy can provide many health benefits, including pain relief, improved circulation, and reduced stress levels but it is important to practice sauna safely and while properly hydrated. If you are new to using saunas, it is important to start slowly and gradually increasing the temperature and duration of your sessions. Be sure to drink plenty of fluids before and after your sauna session to prevent dehydration. Also, listen to your body and stop if you feel dizzy, lightheaded, or uncomfortable.
Lastly, if you are an athlete trying to cut weight, consider doing contrast therapy, which alternates between hot and cold temperatures.