What Really Happens to Your Body When You Use an Infrared Sauna

Foam rollers, ice baths, massage guns — there's certainly no shortage of fitness recovery tools out there. And after a tough lift, long run or high-intensity swim, you might even consider them a necessity, especially if your goal is peak performance.

Now, you can add infrared sauna to your list of treatments to try. There's a lot of buzz and speculation around infrared and its purported health benefits, with workout recovery being one of the most widely touted.

Learn what happens to your body when you use an infrared sauna.

Unlike dry saunas, which use electric heaters or heated stones to heat the air around you, infrared saunas have light panels either on the ceiling or walls that emit infrared light to heat your body through electromagnetic radiation, Minich says.

Infrared saunas usually only get to about 104 to 140 degrees F, while traditional saunas heat to 176 to 212 degrees F, according to Minich.

Here's how they work: Infrared saunas use infrared lamps to warm your body directly, rather than heating up the air temperature, according to the Cleveland Clinic. These lamps create far-infrared light energy that penetrate up to 1.5 inches beneath the skin causing your body to heat up from within, per a November 2012 ‌Photonics & Lasers in Medicine‌ report.

Infrared light has three different wavelengths: near infrared waves (NIR), mid infrared waves (MIR) and far infrared waves (FIR). Each of these wavelengths are a little different, but the far waves are thermal and provide the heat that you actually feel, according to NASA. (You can't feel the shorter waves at all.)

"Infrared light is invisible, just above red visible light," Joel Kahn, MD, an integrative cardiologist who has encouraged infrared as a supplementary tool for some of his patients, says. "It is a form of light therapy, which involves getting exposed to sufficient intensity of infrared light to experience health benefits."

When you sit down in an infrared sauna, the infrared rays warm your body temperature and raise your heart rate, promoting increased circulation, among other benefits, according to the Mayo Clinic.

The skin can only tolerate a limited increase in temperature before burning. "In the case of infrared light therapy, the lightwaves can penetrate the skin and excite the deeper molecules, producing a deep warming effect without burning the skin," Anthony Maritato, PT, licensed physical therapist and owner of ChoosePT1st, says. "This allows for a deeper heat penetration without superficial skin damage or injury."

This is the mechanism responsible for raising your core temperature and all the subsequent purported benefits of sauna use. In fact, the body's core temperature may go up about 2.16 degrees Fahrenheit during a 15-minute Waon (Japanese-based infrared sauna) session at 140F, according to an April 2020 study in the ‌Journal of Thermal Biology.‌

As you look around the sauna, you may notice a glowing red light, too. In some infrared saunas you may be able to change the light color. This colorful light doesn't actually heat the room but rather provides light therapy, which is intended to help improve your skin or improve pain and inflammation, according to the Cleveland Clinic. However, there's no firm research to suggest that light therapy actually provides any health benefits.

After you've settled in the sauna, you can expect to sweat quite a bit, despite that the temperature is lower than a standard sauna and there's no steam, per the Mayo Clinic. That's what makes infrared a better option for those who can't sit through very high heat.

Using any type of sauna, whether it's a dry or steam sauna or infrared, can cause profuse sweating. And sweating a lot can lead to dehydration, Minich says.

Even relatively modest amounts of dehydration (aka less than 1 percent body mass loss due to lack of water) can contribute to cognitive issues such as poorer memory and attention, according to a September 2016 randomized controlled trial in the ‌American Journal of Clinical Nutrition‌.

"Many people are unknowingly dehydrated, especially older adults," Minich says. "Therefore, drinking plenty of water with electrolytes such as potassium, sodium, and magnesium before and after a sauna session is essential to rehydrate and avoid lightheadedness."

Increased blood flow is a big part of muscle recovery after exercise, according to the University of Rochester Medicine. When you train, your body forms new capillaries and brings fresh blood and oxygen into your muscles. This helps you lift, run or jump during your workout.

Your blood is also responsible from carrying your muscles' waste back to your kidneys, which is how your body rebuilds damaged muscle tissue. That's why improved circulation is such a big part of the recovery process.

Infrared saunas are one tool that can help speed your post-workout recovery process, says Dr. Kahn. By increasing your body temperature and therefore heart rate, the sauna promotes circulation, helping heal your muscles faster.

Infrared saunas may also help relieve sore muscles, Dr. Kahn says. Considering the infrared waves are able heat your body from within, they can better penetrate your muscles and tissues.

"Far infrared is known to help with muscle soreness, and near infrared helps with tissue regeneration to help repair and grow muscles faster," he says.

And this seemed to be the case for the athletes in a small July 2015 study in ‌Springerplus‌. Athletes who sat in an infrared sauna with far-infrared waves experienced more recovery benefits, including muscle relief, than athletes who didn't use the sauna.

In addition to your recovery, infrared can also have a positive effect on your performance. After sitting in a far-infrared sauna for 40 minutes at 122 degrees F each night for five days, athletes saw improved muscle activation, better explosive force production and speed performance compared to athletes who didn't use the sauna in a September 2015 study in the ‌Journal of Athletic Enhancement‌.

That said, the researchers did conclude that while infrared is a great supplemental recovery method, it shouldn't replace good nutrition, sleep and muscle massage.

Infrared saunas heat your body from within. And this rise in core body temperature may contribute to significantly increased circulating serum brain-derived neurotrophic factor (BDNF) after 12 to 24 sessions, per the ‌Journal of Thermal Biology‌ study‌.‌

"Research suggests that decreased circulating BDNF is associated with neurodegenerative changes — so if infrared sauna is able to maintain or elevate circulating BDNF, it may have a positive effect on brain function and memory," Maritato says.

December 2020 research in ‌Preventive Medicine Reports‌ on nearly 14,000 people found that regularly using a sauna was linked to a decreased risk of dementia.

Saunas raises your heart rate — just like exercise does — and that's a good thing for your ticker. In fact, sitting in a sauna can raise your heart rate up to 150 beats per minute, which is similar to moderate-intensity exercise, per an April 2015 study in the ‌Journal of the American Medical Association.‌

According to the study, this increase in heart rate can help improve blood pressure. What's more, using the sauna a few times a week is linked to a lower risk of heart disease and premature death, the study found. However, more research is needed to further confirm these findings.

Still, "despite the cardiovascular benefits, those with heart conditions and those taking medications for high blood pressure should check with their doctor before using a sauna," Minich says.

Before you jump into a long sauna session, start slow with a lower temperature, recommends the Cleveland Clinic. Begin with 5 to 10 minutes at a time and slowly increase the time length and temperature as you grow more comfortable.

Make sure you're well-hydrated before you use the sauna and bring a water bottle — preferably with electrolytes — with you to sip on during your session. (Try popping an electrolyte tablet, like those from Nuun [$22, Amazon] into a bottle of water for quick hydration.)

And always aim to shower after using a sauna. "Because sweat is also a way for the body to rid itself of toxins, including heavy metals and pesticides, showering after sauna use and quickly rehydrating will support the liver and kidneys," Minich says.

You don't have to sit in the sauna too long to experience the benefits, but you probably shouldn't be in there much longer than 30 minutes, per the Cleveland Clinic.

As for frequency, aim to sit in the sauna three to four times a week. But when you're first starting out, go for low and slow: Aim to set the temp at around 110 degrees and stay in the sauna for 5 to 10 minutes. As you begin to tolerate the heat with each session, you can gradually increase to 30 minutes a day.

The infrared sauna can be used as a day-to-day recovery tool for athletes and casual gym-goers (or anyone just looking for a refresh). Just as you might experiment with cryotherapy, infrared sauna is another recovery treatment that may offer some benefit but, at the very least, likely won't have any adverse affects if you don't have any contraindications.

If you don't have access to a sauna, infrared lamps (like this one from Vital Red Light) can potentially offer relief from muscle pain or injury.

"These are much lower cost options than large far wave infrared saunas and can be great options for specific injuries," Maritato says. "In my physical therapy clinic, patients may use infrared lamp therapy to reduce pain associated with arthritis at a joint like the knee or shoulder. They don't require large spaces in your home and can be affordable."

While saunas can't cure any ailments, they are linked with very promising benefits for your whole body.

"Infrared saunas are not a panacea of recovery," Maritato says. "The may support healing, but if a person's injury is too severe or the person isn't also doing things like eating well, sleeping well and working to improve other lifestyle factors that affect healing, then an infrared sauna is not going to have much impact on healing, wellness or recovery."

Infrared sauna is just one piece of a larger puzzle that we are all trying to solve. And that's if you can afford it: One infrared sauna session can cost as much as a boutique workout class (upwards of $35 a pop), so there is some investment involved (many studios do offer membership packages).

Another important note: Sauna use shouldn't be prioritized before regular checkups with your doctor. All in all, regularly (and the keyword here is ‌regularly‌) spending time in a infrared sauna can help with recovery, and there's some promising evidence that it can also help support heart and brain health. If your budget allows, picking up a sauna habit might be a smart move. And the peaceful alone time is a nice bonus.