How I'm making my indoor light as healthy as possible

Every year or so I tackle a new area of creating a healthier environment. A couple years ago it was getting rid of as much plastic as possible from my life. Then it was natural fiber clothing. Lately my mission has been improving the quality of my indoor lighting—making it mimic natural sunlight as much as possible.

Part of the motivation for this new health journey has been moving to Alaska this summer. Right now in December there are only a few hours of sunlight a day and when the sun comes out, it's not high overhead but only peaking over the mountains.

The rest of my motivation is learning more about the vast health consequences of both unnatural light and not getting enough natural light.

The bottom line is that adequate natural sunlight is crucial for all aspects of good health, but it's not enough to just get outside everyday. The light we use in our homes and that is emitted by phones and computers can be harmful if it is exposing us to isolated frequencies without the balance of the full light spectrum.

The light spectrum

First, it's important to understand the light spectrum.

This graph is from John Ott's 1973 book Health and Light. I consider his book a classic and highly recommend it for anyone exploring the topic of light. Unfortunately, printed copies are hard to come by and expensive from used book sellers. I'm blessed to have my grandparent's original first edition copy, and you can access a free PDF of it here.

As you can see, natural sunlight ("sun's radiation reaching the Earth") covers the entire visible spectrum of light, plus has tails on both ends that reach into the ultraviolet spectrum on one end and infrared on the other. This means that sunlight exposes you to not only visible light, but non-visible ultraviolet (both UVA and UVB) and infrared radiation (which transfers heat as well).

This spectrum of the sun’s radiation isn’t static throughout the day. In the mornings and evenings, it is shifted towards the red end of the spectrum (emitting a relatively higher amount of infrared—overall the highest exposure is still in the middle of the day since the sun is much brighter then). In the middle of the day, the sun emits the most blue and UV light, relatively and absolutely.

Ott showed through his studies that plants and animals can be significantly impacted by unnatural light spectrums. Exposed to certain colored fluorescent or incandescent light, or even just daylight filtered through a glass window, flowers, mice, and fish could fail to reproduce, develop cancer and other diseases, display manic behaviors, or only produce offspring of one sex.

Today we hear claims that certain parts of the light spectrum—whether it is UV rays or blue light—are harmful. UV is supposedly the cause of skin cancer and skin degeneration (UVB being responsible for sunburns and UVA being responsible for deeper skin aging). In alternative spheres, blue light gets a lot of attention for disrupting circadian rhythms and causing eye damage, among other problems.

But Ott made it clear that no part of the light spectrum is harmful. Rather, all of it has unique benefits. It is only when parts of the spectrum are isolated and we are overexposed to them that they cause harm—whether disrupting sleep, damaging skin, or any of the other effects Ott observed.

An excerpt from page 73 of the book really drives this home (emphasis added):

“In placing a filter of any particular color in a white light source, only the wavelengths of light representing that particular color are permitted to pass through the filter. On first thought it might seem that the resulting abnormal growth responses might be caused by the wavelengths of the color involved. However, these wavelengths that do pass through the filter are a part of the total spectrum of the original source of white light, and the filter cannot add any additional energy to the spectrum of the original light source. It would therefore appear that any altered growth responses must be due to the absence of the wavelengths blocked by the filter, and that the lack of these wavelengths causes a biochemical or a hormonal deficiency in both plant and animal cells. This might be referred to as a condition of mal-illumination, similar to that of malnutrition.”

This doesn’t mean we must be getting the full spectrum, UV to infrared, at all times that we are exposed to light. It means that our overall exposure to light should reflect the full spectrum and the light we are exposed to shouldn’t emit unnaturally isolated spikes of wavelengths. Even the sun’s light emphasizes different parts of the spectrum at different parts of the day and the year. There is certainly still benefit to light therapy devices or bulbs that focus on one part of the spectrum.We'll get into much more detail about this.

There’s a lot of talk right now about the benefits of infrared light. You can get red light panels, go to spas that offer red light therapy, and even buy targeted red light devices like shoes and hats. The benefits include thyroid function, healing skin conditions, collagen production, improved sleep, pain relief, and hair growth.

But we should remember that red light is so beneficial because God created the sun to be healing and beneficial for us, and not just isolated parts of it, but the whole sunlight spectrum. The benefits of UV light get overlooked because of the fear of skin damage, but UV light therapy devices are also available to help with skin conditions, mood, and vitamin D production. Ott focused heavily on the benefits of UV exposure in Health and Light. He claimed that it was responsible for bone health, preventing cavities, children’s growth and development, behavior, immune function, cancer prevention, improved vision, circadian rhythm regulation, and hormone balance.

In fact, even the much maligned blue light on the visible spectrum has important roles like waking you up in the morning and improving mood. However, much of the beneficial affect of blue light comes from stress hormones that it triggers, and blue light causes oxidative stress by generating reaction oxygen species. UV also has an oxidative effect on cells, and therefore many studies of isolated UV rays have indeed shown their ability to damage skin cells.

But remember that stress hormones like cortisol are not all bad—they have important functions in waking you up and increasing energy, and remember that there are many sources of oxidative "stress" in our lives that are not meant to be entirely avoided, they are meant to be balanced and managed. Infrared light is an essential part of the equation. It activates cellular repair mechanisms and antioxidant defenses such as the production of melatonin, a hormone which is not only important for sleep but an incredible antioxidant that balances the oxidative effects of blue and UV light.

So are any of the negative things we hear about blue light right now warranted? It’s certainly not accurate to say that blue light is inherently problematic and you shouldn’t be wearing blue-blocking glasses all day long, but we should be concerned that indoor lights, screens, car headlights, and street lamps have shifted within the last couple decades to much bluer lights, over-exposing us to blue light without adequate balance of the rest of the spectrum, and increasing our exposure disproportionately at night when it’s especially problematic. We’ll discuss more about modern light bulbs and their bluer tendencies shortly. You only need to walk by a house at night with a TV on and observe the color of the window to see how blue the light from TV screens is.

The light from phones, computers, and other devices in the same. You can tell the difference between older and newer cars at night by how warm or cool their headlights appear. Photos like the one below show the before and after effect of switching city streetlights from warmer incandescents to cooler LEDs, which, of course, you are seeing at night.

So the goal is not to avoid blue light as much as possible or maximize only one aspect of the light spectrum like infrared, it's to mimic natural sunlight as much as possible by getting the right parts of the spectrum at the right times and avoiding them at the wrong times.

Beyond the light spectrum

Mimicking natural sunlight isn't just about getting exposure to the whole spectrum. It’s also about timing, location, and brightness.

The sun emits more blue light earlier in the day, when we should be awake and active, and more red light later in the day, when we should be winding down and getting ready for sleep. Before artificial light, people would have received their only lighting in the evening from fire (or an oil lamp, which is essentially a contained fire), and fire's very red-heavy spectrum also would have contributed to healthy circadian rhythms. (Have you ever gone camping, sat around a fire a night because it was the only thing to do without other lighting once it got dark outside, and then went to sleep early and slept like a baby?)

Light lower in our field of vision, such as a setting sun or a fire low to the ground, is also a signal to prepare for sleep, while overhead light (the sun during the day) is a signal to wake up.

Sunlight is also incredibly bright. Even bright indoor lights can be 100x dimmer than the sun outside. The brightness of the sun is not only an indication of the amount of light wavelengths we are getting, but brightness itself is a trigger to wake up and lift mood.

So my goal going forward was to mimic natural sunlight as much as possible inside, in terms of the full spectrum—UV to infrared, brightness, and the location of my lights during the day.

The state of indoor light today

More and more people are talking about the problems with unnatural light today. The issues are multi-layered.

There are only two naturally occurring sources of light—the sun and fire. As already discussed, the sun exposes us to a broad, bright spectrum of light. Fire emits light heavy on the red end of the spectrum, including infrared.

Incandescent light bulbs became common in the early 20th century. Like an oil lamp, they are essentially small fires contained in a bulb and their light spectrum can be thought of as the same. As you can see from the comparison below, as expected, incandescents are normally heavy on the red spectrum. Colored glass on the bulb can shift the spectrum of color emitted.

At nearly the same time, fluorescent lights were invented and became common, especially for being able to easily emit cooler, bluer light desirable for kitchens and other indoor workspaces. As you can see, fluorescent lights cover the visible spectrum, but largely in defined spikes. They can also be manufactured to emit different colors on the visible spectrum.

In the early 2000s, LEDs (light-emitting diodes) became popular, especially for their energy efficiency. LEDs are normally heavy on the blue side of the spectrum and very bright. Like any other lights, they can be modified to emit different colors. They also emit light in somewha narrow, natural spikes, especially on the blue end. In 2023, President Biden enacted legislation requiring energy efficiency standards for lightbulbs, essentially banning the sale of most incandescent bulbs. Today, many new light fixtures don’t even use bulbs; they have built-in LEDs.

LEDs also flicker at a rate that is imperceivable by the eye but is stressful to your body. Sometimes, filming an LED light on slo-mo can reveal the flicker. Higher quality, flicker-free LEDs are available, and more and more newer ones are manufactured this way. To be fair, incandescents flicker too, but at a much lower, less noticeable rate that shouldn’t be a concern.

Largely the reason LEDs are efficient is that they do not emit any infrared light; none of the electricity used by the light fixture is being converted to infrared heat instead of visible light. Some people decry the switch to LED lights for removing infrared radiation from our homes, but it’s important to note that you do not receive any infrared from a lightbulb unless you are fairly close to it—about a foot away. It’s safe to say that if you don’t feel the heat emitted by a light source, you aren’t absorbing the infrared radiation. So, unfortunately, overhead light bulbs shouldn’t be considered a source of infrared light.

Many people in health and wellness spaces right now are advocating switching out LEDs for incandescents (if you can get them). A recent study showed that the introduction of LED lights has disrupted the natural synchronization of women’s hormones with lunar cycles.

But if we aren’t getting infrared from incandescents anyway, and if flicker-free LEDs and warmer colored LEDs can be obtained, what is the benefit of incandescents? Indeed, it does seem that the main problem with LEDs is the over-exposure to blue light—something that can easily be avoided with warmer, dimmer LEDs. Then one of the main concerns left is that, as you can see in the graphs below, the blue end of the LED light is emitted in an unnatural, narrow spike. Incandescents’ light comes from a much broader, more natural range. Ott’s studies showed that isolating any part of the spectrum had potentially serious impacts on human health. Nothing in nature emits light in narrow spikes, so it should be a concern. (As you can see, fluorescents are the worse in this regard.)

However, warmer LEDs may not have this same problem. Below is a comparison of a typical wool white LED and a warm white LED. As you can see, the blue spike in the warm white LED is much reduced. It’s not quite as warm as an incandescent (these graphs don’t show the infrared part of the spectrum but remember that the infrared emitted by incandescents is irrelevant for a bulb you aren’t in close proximity to), and the warm LEDs still contains a small blue blip, may it may not be a problem.

The last cocnern is that one of the main problems with LEDs (including screens) is the emission of blue light without almost any red light along with it. We don’t find this phenomenon anywhere in nature and it may be that we’re never meant to be exposed to blue light without sufficient red at the same time. As you can see, the incandescent still contains much more red than the warm LED.

My conclusion is that high-quality LEDs, used with intentionality in terms of the color and brightness, are probably fine, at leas for warmer lights. I don’t know if the evidence is there yet for anyone to conclude if this type of spectrum has health impacts or not. If someone is concerned about energy usage, I don’t think they should have anxiety about using good LEDs instead of incandescents.

Optimizing my indoor light

Back to my project of mimicking sunlight as much as possible inside my house. To do this, I am using incandescents. I may transition to some good LEDs later, but for right now, I still feel best about the incandescents, especially for cooler lights because they don’t contain the blue spike and still contain more red than LEDs, and I still prefer the incandescents for my warmer lights because they are even warmer than warm LEDs.

My set up also needs to include bright, cooler, overhead lights during the day; warmer, dimmer lights lower in the field vision for early mornings, evenings, and night; and something to provide UV and infrared exposure.

While incandescents have essentially been “banned”, there are several ways to still find them. First, I ordered some online. However, it was hard to find a normal A19 size (I got some that fit a normal E26 bulb base but were a smaller, appliance size that were only 40 watts—not very bright) and I soon found out how warm the “soft white” color was that most bulbs were. I used these bulbs in my bedrooms where warmer, dimmer light was OK, even overhead. But when I put these bulbs in the overhead fixture in my kitchen, I was, honestly, appalled by the appearance. We are used to very cool, brighter lights in these kind of workspaces, and I wanted much brighter, bluer lights in the spaces I spent most of my time during the day—my kitchen and living room— like sunlight would provide.

I ordered several different types of incandescents online, trying increasingly cooler colors that all still appeared far too warm. I collected incandescents from garage sales and thrift stores, but found the same thing. “Full spectrum” incandescents that are meant to provide a more natural, sun-mimicking light used to be easy to buy, but the only ones I could find now were old ones on eBay that were quite expensive.

Websites like healthlighting.com sell new full spectrum incandescents, but they are fairly expensive—about $13 a bulb not including shipping.

Now to share my favorite healthy lighting hack that I was thrilled to discover: You can buy full spectrum incandescent lights for a fairly reasonable price, regardless of bans, at even your local Wal Mart. Yes—they’re found in the pet section.

Look for full spectrum incandescent neodymium reptile heat bulbs. People recognize that reptiles kept indoors need bright, sun-mimicking light, and the infrared from the incandescent provides a heated basking spot. From my research, they are essentially identical to he more expensive full specrum incandescents you can buy online.

They come with a warning that these are intended only for animals. Why are animals treated better than humans?

If the government is telling me not to do it, I’m probably on the right track.

Now, when I tried these light bulbs in my kitchen fixture, they were still too warm, but I put them in my bathroom where a little warmer light was OK, but where I wanted something brighter than the very warm 40-watt bulbs in my bedroom.

I finally found the solution with reptile “daylight blue” incandescent bulbs. The glass appears dark blue but in a light fixture, they emit a cool, white light that looks like sunlight. I ordered 150-watt ones online—the brightest I could find—because my local Wal Mart only sold a 60-watt version in-store. These bulbs are now in all my overhead kitchen and living room fixtures. For lights where I want cooler light like these overhead lights (both because I want bluer light exposure during the daytime and because we expect cooler lights in workspaces like this—it’s the reason houses usually had fluorescent lights in kitchens before LEDs were common) I definitely want an incandescent rather than higher-quality LED because it is the only option that provides light than appears cool white but sill has more red in the spectrum simultaneously.

Since I only want these lights on during the day, I put warmer incandescents in lamps around the my kitchen and living room for turning on early in the morning and after the sun goes down. These are redder in appearance, lower in the field of vision, and much dimmer. My house is not highly illuminated at night. It is enough to see what I am doing, but it is a much different feel than the lights that are on during the day. This is how fires and oil lamps would have made your home feel before bright lightbulbs were invented and it’s very relaxing.

I believe this setup makes a positive difference for my whole family’s sleep. While many people in my extended family can’t sleep without taking melatonin every night, we all fall asleep easily, even the two-year-old and four-year-old. When I visit someone’s house or go somwhere after dark where there are bright overhead lights, it seems like we all take longer to fall asleep.

Indoor UV and infrared

So far my setup has covered the visible spectrum, brighness, and ligh placement, but I want to make sure I am also getting those invisible tail-ends of the light spectrum—the UV and infrared radiation.

Since the benefits of infrared are so well known, there are lots of infrared light therapy devices available. They deliver a powerful dose of infrared light without too much heat, which can be hard to tolerate. However, most use LED lights. I’m concerned about the unnaturally narrow spectrum of light emitted by these red LEDs, so I’d rather get my infrared from an incandescent. This is why I use infrared chicken heat lamp bulbs. They are also a fraction of the price—about $14 instead of hundreds or thousands for an LED light therapy device, and I like the heat emitted from them. I use mine to warm me up when I wake up and sit down to read my Bible in the morning and when I lay down to read in bed at night, which also means I am spending more time under these lights than someone who dedicates ten minutes a few times a week to sitting in front of their red light therapy device, so I am still getting a good dose of infrared overall despite the lower infrared output of my chicken lamps compared o a red light therapy deivce. If an LED red light therapy device works better for someone, I think it would still be a good option. I ordered 250 watt (for maximum brightness) incandescent infrared chicken lights like this one from Amazon.

For UV exposure, there are also UV therapy devices available, which can be a good option, but like the red light therapy devices, they can be expensive. However, again, people recognize that pets need full spectrum light, and affordable UV lights for reptiles are easy to find. I got a mercury vapor reptile UVB bulb (which are sold because UV exposure is important for reptiles to maintain normal feeding and reproductive behavior!).

Some UV reptile bulbs emit primarily UVA or don’t disclose their UVA/UVB ratio. We get some UVA exposure through windows, whether in your home and car, so I wanted something with a higher proportion of UVB. A mercury vapor bulb seemed the best option for avoiding flicker compared to fluorescent and LED options, but LED UV lights may have a broader more natural spectrum. I hope to be able to find better data about light spectrums emitted by either, or be able to get a spectrometer to test them myself someday. Either way, I always have my UV lamp on with my infrared chicken light simultaneously so that I am not being exposed to UV and blue light without red and infrared to mitigate oxidative effects and other concerns with isolated blue exposure. I use this set up only during the day, and right now while I experiment, never for very long.

It should go without saying that my indoor light is still nowhere near identical to the sun. Just in terms of brightness, for example, midday sun can range from 10,000 to 100,000 lux. Exposure directly underneath my five 150 watt kitchen bulbs might be a couple thousand.

There’s no replacement for spending as much time as possible in real sunlight. But I want to optimize my indoor set up so that when it’s hard to get outside (as I write this it is 19 degrees outside with about 50 mph winds) I can still get as many of the benefits as possible, and so that the light I am getting exposed to when I am inside (like we all are, at least some of the time) is as beneficial as possible rather than harmful.

As you can tell, there’s still a lot I don’t think anyone knows yet about light and its effect on human biology. Much of my approach is educated guesses, but it’s all based on the assumption that what God provides—bright full spectrum sunlight with its natural changes throughout the day— is the most beneficial thing we can aspire to attain. We will never be able to replace it, we certainly can’t do better, and the best we can do without it indoors is to try to bring it inside as much as possible.

Ultimately, my goal is to build a house where the main living space is Walipini-style Earth-sheltered greenhouse with full-spectrum plastic windows for simply having real, bright sunlight shining straight into the home rather than being blocked with a roof and then mimicked with light bulbs. Follow along for updates on that project, God-willing, in the near future.