How does IR and UV affect health?

In part 1 we learned about the importance of light exposure to entrain our circadian rhythm and the dangers of blue light and how to manage it with glasses, apps, or avoidance.  While management of blue light is certainly a great place to start, there is so much more to managing our light exposure. In this post, we’ll delve a little bit deeper into light—the good and the bad.

Let’s start with the “bad” light. We already learned that blue light is not bad, its just the amount we get (dose) and the time of day in which we get it that are problematic.  The same is true of the “invisible” spectra of light. Lets take a minute to explore infrared (IR) and ultraviolet (UV) and their impact on our health.

When we think of sunlight, we generally think of visible light. After all, this is what lights our day, fuels plant life, and gives us such gorgeous sunsets each night. However, visible light constitutes only about 40% of the sun’s radiation reaching earth. The majority–or about 55%–of solar irradiance reaching the earth’s surface is IR, and the balance is made up of UV radiation (5%).

Although it is only a small fraction of solace irradiance, UV light has an outsized role in human health with its ability to cause damage (both dirtect and indict) to the DNA inside our cells, leading to skin cancer, photoaging, and sunburns. Sunblock and other SPF materials specifically block the action of UV radiation on our skin. The amount of UV radiation emitted by the sun varies by the time of day. In the early morning and late evening, UV radiation is at its lowest. UV irradicance peaks at “solar noon” which is essentially mid day, but can be later during daylight savings time.

Although there is no such thing as “bad” light, UV is probably the closest thing. While there is no doubt that UV exposure needs to be mitigated, conventional wisdom is to avoid all UV exposure at all costs. But stop and think about this from an ancestral health perspective? Our ancestors have lived and worked in the sun without SPF clothing or sunblock for millennia and they didn’t drop dead from skin cancer. What gives?

To get a better understanding, we need to get to know UV’s distant cousin from the “other side” of the spectrum: Infrared (IR). Infrared light (or IR radiation more precisely) is much higher wavelength than UV and penetrates more deeply into the body’s tissues. It is indeed the most plentiful type of radiation in sunlight and is perceived in the body as heat. Although IR does not vary quite as much during the day as UV, the ratio changes substantially and in effect the morning and evening light is rich in IR and low in UV.

Now, back to our paradox regarding the potential danger of UV exposure and the fact that humans have lived with UV light exposure throughout all of history. One plausible explanation is that we simply aren’t getting enough IR exposure to offset the damage done by UV. It is possible that the IR-rich morning sun “primes” the skin for UV damage that will come later in the day. Likewise, evening IR exposure may help mitigate some damage in a process known as photobiomodulation. It’s an interesting phenomeon with both mechanistic and experimental support. So does this mean you can run around shirtless all day at the beach, not use sunblock on your face, and expect to live a wrinkle-free and cancer-free existence? NO! But it does help explain how humans have coped rather well with this natural phenomenon for millennia. A wise approach is to take the middle ground: if you are going to be in the mid day sun and exposed to the full onslaught of its potentially damaging UV rays, make sure to get some IR-rich early AM and PM sunlight exposure to modulate the effects.

Enough about the negative aspects of light. Lets turn to the positives. We already covered the importance of getting some of the sun’s full spectrum light each day to activate Vitamin D— preferably in the morning hours when the UV irradiance is lower. But if morning walks aren’t an option with your schedule or latitude, it might be smart to look into a red/infrared therapy device, like Joovv. Joovv is a door/wall-mounted red/infrared light array that has a decidedly weird vibe. We’ve been using it for months, and while I remain somewhat skeptical of some of their claims, I find it to be an enjoyable experience that improves mood and energy levels. Some claim that it helps with sleep, libido, and joint/muscular recovery for athletes, among other things.

Science on infrared therapy has been around for decades, and esticians and dermatologists have used it for years to help with collagen formation and wrinkle reduction. Red light, unlike blue, is actually sleep promoting. Imagine your ancestors huddled around a fire after sunset–the only light spectrum available is red. We are adapted to red light in the evening. It may be diffeicult to replicate this environment in your home without looking like a brothel, but simply switching out a few bulbs for red or amber hued incandescent bulbs is a good place to start. With advent of biohackers and athletes promoting its use, red/infrared therapy has come mainstream. We’ll post a review after we’ve had enough time using it to make a full judgement (and we have NO affiliate relationship).

Well, that’s all you’ve ever wanted to know about light! While management of different types of light can be difficult, confusing, and even controversial, there are a few pretty clear take home points. Let’s recap what this means for you:

• Wake up with the sun. It will be good not only for your mental health to see a beautiful sunrise, but also for your physical health to wake up and catch some of those early morning rays which are rich in infrared and relatively low in ultraviolet. Exposure to morning light entrains the circadian rhythm, and as an added bonus, it’s both peaceful and invigorating.
• Exercise, work, or play outdoors if possible, but limit mid-day hours with peak UV irradiance. If you’re going to be out during those hours, ensure to ‘prime” with some morning IR exposure. If you do go out in mid-day sun, be sure to use sun protective clothing and/or mineral based sunscreen, NOT chemical sunscreens with toxins like Oxybenzone and octinoxate.
• Limit blue light to daytime hours and use blue blocking lens or apps on your digital devices to mitigate exposures. Embrace the calming and sleep-promoting aspects of red light on the evenings after sun-down. If you can afford it, consider a red light therapy device