What is Infrared Light [2021 Guide]

Light you can’t see but can feel

Written by Christopher Kiggins

What is Infrared Light What is Infrared Light

Before we get into the details of how infrared light is used in saunas, it’s necessary to understand the core principles of light energy.

What is Infrared Light?


The light spectrum seen above (also known as the electromagnetic spectrum) moves from the shortest light wavelengths on the left to the longest waves on the right. The lengths of the waves themselves correspond with the respective heat they produce. Violet has the lowest temperature with the shortest visible wavelength. On the opposite side, red has the hottest temperature with the longest wavelength.

The most biologically damaging light waves are gamma rays, which are the shortest on the entire light spectrum. This is what bad guys use to vaporize people in comic books. The next light waves on the spectrum are x-rays, and they are related to gamma rays in that they are also biologically hazardous. 

The next invisible light on the spectrum is ultraviolet light which accounts for about 10 percent of the light energy coming from the sun. In big doses, these rays are also harmful. Visible light is the next portion of the spectrum and allows for our sense of sight and color.

The reason why humans see different colors is because objects either absorb or do not absorb these different light wavelengths, or frequencies, bouncing and reflecting off objects. The reason why you can see a red apple is because the organic compounds of the apple absorb every color but red. As you move down the visible spectrum of colors from purple to indigo to blue to green to yellow to orange to red, the light wavelength becomes longer.

The last and longest wavelength (700 nanometers) visible to the human eye is red. After that, light is invisible to the human eye. This is where infrared light exists. “Infra-red” actually means “below red.”

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Infrared light is invisible to humans, but it radiates energy which we feel as heat. Additionally, it can be focused and reflected just like visible light. It can even be harnessed and pointed at objects for them to absorb. The only difference is instead of seeing the color of the light, you feel the invisible light wave as heat.

Infrared naturally comes from the Sun. In fact, the Sun’s energy consists of 50 percent infrared light at the level of Earth’s atmosphere, and at ground level infrared energy accounts for 53 percent of light—we just can’t see it. But we feel it! (In some places more than others!)

All types of light penetrate into objects, not just infrared. As this light infiltrates an object its radiant energy (also know as electromagnetic radiation) is absorbed by that object at the molecular level, causing the thermal motion of the object’s particles—effectively ‘charging’ them.

In layman’s terms, the absorbed heat moves or charges the object’s molecules. As a result, the object’s core/internal temperature will increase based on the level of absorption.

Just as certain objects absorb different colors, as in our red apple example above, objects have different organic properties which allow them to absorb different levels of infrared!

We understand heat as humans either from thermal radiation (infrared light), an object emitting heat into the air (convection) or by touching an object directly (conduction). That’s it. There are only three ways to feel heat! Most of the time when you feel heat, you feel infrared. Almost all thermal radiation consists of infrared wavelengths, which means that all objects that emit heat also emit infrared.

This is my favorite example:

When you are walking outside on a hot summer day past a brick building in direct sunlight, if you put your hand a few inches away from the bricks but you don’t touch them, you still feel the radiant heat coming off of the brick—that’s infrared! 

The Sun’s infrared light has actually heated the ceramic bricks from the inside (through absorption) and then the heat is released in the form of infrared light. You experience this light as heat. This is how infrared night vision works—it’s picking up on your radiant infrared energy.

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I am glad infrared saunas have developed the way they have, because I couldn’t imagine my life without the benefits they provide, like deep sleep, lower blood pressure, less joint pain, weight loss, and a boosted immune system. Here at SaunaCloud I sell saunas that are some of the best history has offered. My far infrared saunas use advanced ceramic-carbon combination heaters for an amazing sauna experience. For more information on how SaunaCloud’s infrared saunas work and how they can improve your health, download my book The Definitive Guide to Infrared Saunas. Just give us a call at SaunaCloud 1.800.370.0820.

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Christopher Kiggins | Sauna Enthusiast

Christopher Kiggins | Sauna Enthusiast

I have been writing, learning, educating and generally pointing people in the right direction infrared sauna wise since 2012. Let me know how I can help: chris@saunacloud.com - (530) 417-1220