In some ways, we are all looking to improve upon the human condition. No matter the reason for turning to a light, it’s still perplexing even for the most brilliant minds. An introductory understanding of the infrared light, to become a ritual for many is essential.
What is light?
Light is electromagnetic radiation, or radiation in the form of a wave. You can think of light as energy that travels through the air with a specific frequency, or wavelength. The shorter the wavelength, the more energy the wave contains; the longer the wavelength, the deeper the wave can penetrate into human tissue. Wavelengths of light are measured in nanometers (nm). Nano means 10-9 or a billion times less than a meter.
This spectrum includes both visible light that humans can see, like red and blue light, and also invisible light like infrared (IR) light. Visible colour in light comes from the length of the wave as well and how our eyes perceive them. The energy in light is dependent on the wavelength and the colour is how the human eye and brain make sense of light’s electromagnetic wavelengths. The visible spectrum of light makes up a very small portion of all electromagnetic radiation.
What is Infrared light?
Infrared light (in the mid-600 to 1000s nm range) has a much longer wavelength than UV, green or blue light. That allows wavelengths of infrared light to penetrate deeper into the body, for further-reaching deep tissue healing and regenerative effects. Infrared (IR) light can support muscle health and enhance the body’s natural recovery and healing processes. Infrared light has been shown in numerous studies to enhance cellular function, by stimulating the mitochondria in our cells to produce more ATP cellular energy, which powers everything humans do. Research has also found numerous detoxifications, skin health, inflammation, and sleeping benefits.
A home device like the Smomar Infrared Sauna Blanket uses a carbon heater to shine infrared light on your body during a treatment session. This is just like the wavelengths of light your body needs from natural sunlight, but without the UV rays that cause sun damage.
The science of infrared therapy in the human body
Infrared light therapy works because healthy light intake is crucial for our health. It’s essential for our cellular function and energy production, just like water, sleep, and the nutrients from food. Unfortunately, most people don’t get as much natural light as they need for optimal health (the average Brit spends over 90% of their time indoors).  Infrared light therapy is an easy solution for getting more healthy light everyday, in the comfort of your home, regardless of the weather or season.
Clinically-proven wavelengths: Not just any light will do. The best infrared sauna blanket devices use safe, clinically-proven wavelengths of infrared light: mid-600 to 1000s nm range.
Humans have trillions of cells, and each one needs energy to do their job and keep our bodies in balance. We convert this energy from food, water, and oxygen, and do so most efficiently in a vital process called cellular respiration. The product of cellular respiration is adenosine triphosphate (ATP) energy that our body uses every second. The more efficiently we can create ATP, the better we feel and function.
Infrared light improves the efficiency of the cellular respiration process and helps your body make and use ATP energy more effectively. Infrared light does this by impacting the mitochondria , the energy power of your cells. Your infrared light session can increase the number of mitochondria , and also boost their function in the cells. 
In short, Infrared light therapy treatments can stimulate the electrons involved in the mitochondria during cellular respiration, and help clear out nitric oxide (NO), which is a harmful roadblock to ATP production.  Essentially, NO junk up the cellular system of ATP production, and Far Infrared (FIR) light helps prevent and reverse this problem. The photons in FIR light excite electrons, which helps break up nitric oxide bonds, so hydrogen ions can move through the process more effectively, resulting in greater levels of ATP energy that power your cells and body and help you lose weight. 
That’s a broad summary of a very complicated, microscopic process. For a more detailed look at how Infrared light impacts cellular respiration, you can read this overview of the medical application of infrared light and ATP process.