October 18, 2023

Beyond Heat: The Benefits of Infrared Light for the Immune System

Longevity, Immunity

We hear a lot about the benefits of high heat for strengthening the immune system, but did you know infrared sauna does not have to get extremely hot to be effective? This article explores how infrared light aids the immune system independent of the high heat required by traditional saunas.  

For those who don’t feel well in the extreme heat of a traditional or steam sauna, or who simply don’t enjoy it, Sunlighten infrared saunas offer benefits of light therapy effective without high temperatures.  

Exposing the body to heat strengthens the immune system through a process called “hormesis,” which is the idea that a little bit of stress on the body is a good thing. Exercise and fasting are two examples. Sauna also causes the body to respond to the heat. Because infrared produces a special kind of heat, it also delivers the benefits of light, albeit invisible light. 

Here’s what you need to know about infrared light and its healing effects on the body without heat. 

Infrared is both (invisible) light and radiant heat 

Ready for a physics lesson? Our Science Advisory Board member, Michael Hamblin, Ph.D., a distinguished visiting professor at the University of Johannesburg in South Africa has studied photomedicine (a branch of medicine that studies and applies light to health and disease) for 30 years to explain the connection between infrared and heat. He explains that infrared encompasses the qualities of both heat and light. 

“Heat is the motion of molecules,” says Dr. Hamblin. “Molecules vibrate and the energy in that vibration is heat which increases the temperature. Infrared is an electromagnetic wave that’s also energy but a different physical quantity from heat. When infrared is absorbed by material –in this case, the body – it makes it hotter.” That’s because infrared increases the vibration of the molecules in the body which in turn raises the body’s core temperature.  

Dr. Hamblin adds that anything that can absorb infrared can also emit it. When this happens, the temperature goes down and the material gets cooler.  

Infrared light isn’t one-size-fits-all

There are three types of infrared light: near, mid, and far, and the body absorbs each one at different levels. For example, near infrared (NIR) is absorbed at a cellular level, making it ideal for boosting mitochondria and increasing collagen production. NIR will also deliver the lowest heat level, warming the body rather than causing the type of heat that leads to perspiration. Far infrared (FIR) penetrates deeper into the body because it’s soaked up by water molecules in the body. This helps improve health at a cellular level because the light can reach muscles and tissues. As such, FIR will raise core body temperature and stimulate sweat glands because it creates more heat. Mid infrared (MIR) acts a lot like FIR, and helps with heart health, circulation, pain relief and muscle recovery. 

You don’t need extreme infrared heat to get its benefits 

“Exposure to Infrared produces biological effects without necessarily heating up the body,” says Dr. Hamblin.  

Research published in the Journal of Photochemistry and Photobiology studied how infrared radiation boosts immune function compared to heat alone1. The researchers of this study found that infrared light enhanced the activation of epidermal Langerhans cells – a type of white blood cell that protects the body against viruses and bacteria. This means infrared light has heat-independent biological benefits when absorbed by the body.  

“When the skin is exposed to infrared light, it also hits the blood vessels,” adds Dr. Hamblin. As blood circulates throughout the body, the benefits from that infrared absorption travel with it. This means that even though infrared light is at first absorbed superficially, it can still affect the entire body.” 

Sunlighten infrared therapy is customizable 

Traditional saunas heat the air with steam. This heat causes you to sweat, setting off a physiological process of dilating the blood vessels to increase circulation and promote healing. 

With infrared therapy, instead of heating the air, the body absorbs infrared light and as a result, it can heat up if the power is high enough. This means that those who don’t enjoy or can’t handle high amounts of heat can control the power of emitted infrared wavelengths.  

At Sunlighten, our products have a range of infrared light options. For example, the mPulse Smart Sauna delivers LED NIR and red light therapy to help the body take in infrared at lower levels to prevent overheating. And, with 3 in 1® infrared technology integrated with red light, you can choose which wavelengths work best for your health goals: NIR/RED, MIR, and/or FIR.  

It's important to remember that infrared therapy isn’t synonymous with high heat. From targeted, portable infrared light therapy available in the Sunlighten Solo System or handheld lumiNIR wand, to the cabin experiences offered by our Signature collection, infrared therapy is an option for everyone and every home.  

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WRITTEN BY: Colleen Travers

Colleen Travers is a health and wellness freelance writer focusing on all things that make you feel healthy and happy from the inside out.  She's been an editor for sites such as and Her work has appeared online in outlets like Reader's Digest, SHAPE, HuffPost Life, Peloton, Fitbit, MindBodyGreen, and more.