Light 101: What is Light?

Light is an essential ingredient for all life on earth. It’s fundamental to human health, and light is a key component of a balanced lifestyle, just like diet, exercise, and sleep. But light is often overlooked as a major contributor to health and well-being. And most people don’t get nearly enough sunlight: the average American spends over 90% of their time indoors, surrounded by bright artificial light. [1]

This article explains the basics of light: the sun, the light spectrum, different wavelengths and colors of light, red and near infrared (NIR) light, and the possibilities of light therapy.

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. 

The full spectrum of light (also called the electromagnetic spectrum) includes numerous wavelengths of light with different frequencies and colors, like red light (in the mid-600s nm range) and blue light (in the 380-500nm range).

The spectrum includes both visible light that humans can see, like red and blue light, and also invisible light like near infrared (NIR) light. Visible color 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 color 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. 

The Importance of Sunlight: Sunlight’s importance cannot be overstated: all life on earth relies on the sun. The sun powers plants that keep our atmosphere filled with oxygen, which sustains human life. The sun’s cycles help to heat and cool our oceans, allowing our atmosphere to circulate, with an important role in cloud formation, rain, and the storage of carbon dioxide. [2] This light from the sun energizes and restores the human body as well. Light is essential for keeping life on earth healthy and balanced.

The sun shines full-spectrum light, meaning its rays contain all wavelengths of light, visible and invisible. Full-spectrum sunlight contains many different wavelengths with different energies  that humans need to stay healthy, but it also includes hazards and less beneficial wavelengths. Fortunately, the earth’s atmosphere filters out much of the less beneficial light from the sun, including a large amount of gamma and ultraviolet wavelengths that are riskier in abundance. 

Different Colors of Light have Different Health Effects

Not all light is the same: different wavelengths and colors of light have different physiological effects on the human body. Below, we break down various colors and wavelengths of light, and what we know about their health effects on people.

Ultraviolet (UV Light): Ultraviolet light (100nm-400nm) is invisible and has short, powerful wavelengths. UV light from the sun is what’s responsible for tanning or burning your skin. UV light is also responsible for supplying the body with Vitamin D. In 1935, scientists confirmed that UV light helps humans produce and maintain vitamin D3 levels, which allow the body to effectively absorb calcium from food with our intestines. [3]

Blue Light: One of the most commonly isolated wavelengths of light is in the 380-500nm range, which our eyes perceive as very bright blue light. Blue light is isolated and used in most of our modern screen technology, from TVs to phones to tablets to computers. Blue light is very good at illumination, and an efficient source of light for electronics. It’s also been found to have some positive effects for bacterial acne and teeth whitening. 

However, blue light also has downsides and negative effects for human health. Because blue light is so bright, with a higher color temperature than daytime sun, it makes your brain and body think it’s time to be wide awake. So if you take in too much blue light at night, you can knock your circadian rhythm out of balance and develop sleep problems. [4], beyond potential risks to your eyes [5].

If you want to learn more about blue light and how red light can help counteract the negative effects of blue light, check out this article. 

Green Light: Green light, in the 520-560nm range, is less well understood than blue and UV light. Researchers are still studying the effects of green light, with some initial trials showing potential anti-inflammatory effects in laboratory animals. More research is needed to examine the specific effects of green light on human cells and tissues. [6]

Yellow Light: Like green light, yellow light is still being researched and explored by scientists. Yellow light is in the 570-590nm range, and early studies have pointed to potential benefits related to skin health, but more studies are needed to draw conclusions. [7]

Red Light: Red light comes from wavelengths in the mid-600nm range. Red light is visible and has been studied in thousands of clinical trials and medical studies. The health benefits of red light are well-established. In the early 1990s, NASA found that red light could activate plant growth in space, in the absence of sunlight. This and other earlier discoveries led to far greater clinical interest in red light therapy. You can read more about the history of light and red light therapy here. 

Red 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 skin health, inflammation, and recovery benefits.

Near Infrared (NIR) Light: Near infrared light (in the mid-700 to 1000s nm range) has a much longer wavelength than the previous colors we’ve mentioned. That allows wavelengths of NIR light to penetrate deeper into the body, for further-reaching deep tissue healing and regenerative effects. NIR light can support muscle health and enhance the body’s natural recovery and healing processes. You can see more about how Joovv uses pulsed NIR light for Recovery+ mode here.

Mid and Far Infrared Light: Mid and far infrared light are commonly used in saunas, to heat up the body and promote sweating. You can read about how red light therapy differs from saunas here.

Red and Near Infrared (NIR) Light Enhance Cellular Function and Health

The existing body of research on light and human health shows that red and NIR light are the most beneficial wavelengths, with the fewest risks and downsides. UV light is crucial for vitamin D, but it can also be dangerous when you absorb too much. Blue light similarly has upsides and serious downsides. Red and NIR light have shown a wide range of potential health enhancements, with relatively little risk and few side effects. 

Thanks to today’s LED technology, Joovv is able to isolate specific wavelengths of red and NIR light and deliver it directly to the skin and cells. Red light therapy is essentially taking the most beneficial wavelengths of light we get from the sun, and avoiding everything else, so you can target the mitochondria and enhance cellular function and energy production across the body. In conjunction with a healthy lifestyle, absorbing red and NIR light supports biological balance and overall health. 

Conclusion: Light is Key for Balance and Good Health

Light is key to all life on earth, and it’s essential for human health and function. Light is energy that travels through the air with a specific frequency, or wavelength. Full-spectrum sunlight comes in various colors and wavelengths, like red and NIR light. Most people don’t get nearly enough light from their environments, which can have negative health consequences. Red and NIR light in particular has been shown to enhance cellular function, and support healthier sleep, skin, and recovery.

Joovv red light therapy devices isolate these wavelengths of red and NIR light and deliver them directly to your skin and cells. This lets you supplement the light you get from the sun, in the comfort of your home. 

Sources and References:

[1] Klepeis NE, Nelson WC, Ott WR, et al. The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants. Journal of Exposure Analysis and Environmental Epidemiology. 2001 May.

[2] Climate Variability. NASA.

[3] DeLuca H. History of the discovery of vitamin D and its active metabolites. BoneKey Reports. 2014 Jan.

[4] Moore, R. “Suprachiasmatic nucleus in sleep-wake regulation” Sleep Med. 2007 Dec.

[5] Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology. Mol Vis. 2016; 22: 61–72

[6] Catão MH, Costa RO, et al. Green LED light has anti-inflammatory effects on burns in rats. Burns. 2016 Mar.

[7] Chen L, Xu Z, et al. Light-emitting Diode 585nm Photomodulation Inhibiting Melanin Synthesis and Inducing Autophagy in Human Melanocytes. Journal of Dermatological Science. 2018 Jan.