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What if I told you there was such a thing as mal-illumination? Similar to malnutrition, it’s when you’re deprived of biologically necessary light.
Many of us spend large portions of our day completely disconnected from natural sunlight. In the winter months, we may even go entire weeks without spending a moment in the sun!
Instead, we bask in man-made light spectrums that pay no heed to our ancestral origins or biological needs. These spectrums often have wildly unnatural visible wavelength ratios and are completely lacking all beneficial infrared and ultraviolet wavelengths. Not to mention, the dimness that often accompanies these environments is an issue all its own.
This is obviously untenable if we hope to stay functionally healthy for a long period of time. Human beings need full spectrum light exposure for optimal health.
Full spectrum sunlight is necessary for optimal eyesight, digestion, sleep, movement, repair, and detoxification.
Of course, since we spend a large portion of our time inside structures that block most of the natural light from the sun, we must consciously work to bring these missing spectrums back into our indoor spaces.
If we hope to emulate it, let’s first go over just what sunlight is.
What is Sunlight?
The only natural source of radiation comes from our Sun, and all life on Earth has adapted to this form of energy over the course of billions of years.
What Does Sunlight Look Like?
Let’s start with the spectral makeup of natural light, so that we can better conceptualize what we need to copy.
Below is a spectral distribution graph of sunlight as it passes through the atmosphere.
This can be broken down into the following percentages:
- UVB: <1%
- UVA: 8%
- VIS: 44%
- IRA: 32%
- IRB: 14%
- IRC: 2%
As you can see, there’s quite a bit of visible spectrum radiation coming from the sun, and it’s fairly even across the board; although there’s usually a slight bump in the blue-green area throughout most of the day.
There’s also a fair amount of UVA and tons of infrared energy in sunlight.
The Color of Sunlight
The appearance of sunlight changes throughout the day in relation to the amount of high frequency light it contains.
The color of sunlight and all artificial sources of light are expressed in Kelvin, or the apparent “color” of a heat source. As the heat source rises in temp it becomes “cooler” in appearance.
The color temperature of sunlight in space is about 5900K, but by the time it reaches earth on a clear summer day, this dips down to about 5200K to 5700K due to the Rayleigh scattering of the shorter wavelengths, hence the blue sky.
As you can see, throughout most of the day (9AM – 6PM) the color temperature of the Sun was between 5000K and 5700K.
And below is a minute by minute spectrograph capture of sunlight from 7 am to 12 pm for an idea of how sunlight changes during sunrise.
When it comes to choosing artificial lighting, you’ll be looking for lights that correlate with this trend by choosing something >5000K for the daytime, and <3000K for the evening.
Natural Light is Bright and Powerful!
One of the most important aspects of natural light is that it’s very bright!
The Sun’s radiation hitting the Earth at the equator hits a peak of about 1,120 W/m2. Over the course of a year, this averages out to around 340 W/m2.
All of this power culminates in a very bright source of light, with sunlight producing about 93 lumens per watt. Meaning, at equatorial noon we should see about 104,160 lux (lumens per square meter).
If we averaged an entire year over all locations on the Earth’s surface, the average solar irradiance would be about 170 W/m2 per day and about 16,000 lux. These change based on the specific area, if we’re in cloudy Scotland, the year long daily average is closer to 72 W/m2 and about 7,000 lux.
As you can see, the Sun is a powerful, bright radiating machine, and our indoor environments usually pale in comparison.
One of the most beneficial things we can do for our health is to simply increase the brightness of our interior lighting.
Getting More Natural Light Indoors
Now, before we begin adding artificial “sunlight” to our homes and offices, let’s make sure we’ve done everything we can to let in real light first.
- Let the light in: Let as much light in as you can by opening your blinds and windows. If you have an issue with glare, it would be better to apply anti glare film than to cover the window with curtains or blinds. If only a portion of your window is the trouble spot, you can choose to apply a small portion of anti glare film, so that more light can get through the rest of the window.
- Be near the light: Wherever you spend the most of your time, most likely in your office or family room, make sure it’s near a window. At work, try to get a location nearest a south facing window, east would be second best.
- Hardwood floors are better than carpet: Hardwood floors will reflect more light into a room than carpet will, and light floors will reflect more than dark. Something to consider for future renovations?
- Brighter paint colors: Wall color hues with more white in them (think lighter) will reflect more light around the room. Go with a satin variant here to maximize reflections without making imperfections too obvious. If you’d like, you can use a warmer hue in the north facing areas of the house as these windows will receive slightly bluer light, while south facing areas will receive warmer light in comparisson.
- Add privacy window film: If privacy is a concern with certain windows, try applying window film. This will allow you to feel secure while still allowing sunlight in.
Replicating Full Spectrum Visible Light
Light Bulb Test Data
During the writing of this article, I did quite a bit of light bulb testing.
Here are the results of that testing!
Now onto the practical portion of this guide! The first item on our list is visible light.
Visible light is the portion of sunlight responsible for setting your circadian rhythm, meaning it’s the most important part. If you choose to implement only one part of the spectrum of sunlight, this would be the one.
The Science Behind Full Spectrum Visible Light
The beneficial effects of bright full spectrum light are too numerous to count.
This is a resource section for anyone who wants to explore the science a bit more or needs some intellectual ammo at work for why you want to change your lights.
- A Literature Review of the Effects of Natural Light on Building Occupants cites hundreds of examples of bright full spectrum light being beneficial in every scenario imaginable. [R]
- Ambient lighting brightness appears to be very important for proper refractive development in young animals, with dim light being significant in myopia development. [R]
- Exposure to sunlight and ultraviolet light is associated with a decreased incidence of myopia development. [R]
- Bright ambient lighting retards the development of form-deprivation myopia in monkeys. [R]
- Recovery from form-deprivation myopia in chicks was significantly better under full spectrum LEDs when compared with fluorescent light of the same color temperature. [R]
- In a study of 27 children, the majority had better eyesight under a 5500K color temp light vs 3600K. [R]
- Time spent outdoors in bright sunlight reduces the chance of developing myopia. [R]
- Bright light exposure at home is associated with less sleep disturbance, anxiety, stress, and depression. [R]
- In a group of call center workers, switching from a low CCT light source (2900K) to a high CCT (17000K) resulted in improvements in wellbeing and work performance. [R]
- Bright light sufficient to trigger a circadian response improves sleep, mood, and behavior in dementia and Alzheimer’s patients. [R]
- In this study, hens preferred spending time under bluer florescent lighting over incandescent light of the same lux. [R]
- In a study involving 313 workers, exposure to more full spectrum sunlight resulted in 63% fewer headaches, 56% less drowsiness, and 51% reduced eyestrain. [R]
- Evening melatonin secretion and peripheral heat loss occurs earlier in office workers exposed to brighter light. [R]
- Exposure to adequate amounts of blue light is necessary to set the circadian rhythm and bring about a massive cascade of biological processes on a daily basis. [R] [R]
- High energy wavelengths like blue light can cause retinal damage, it’s important that lighting is bright enough and even across spectrums so that the retina is properly dilating. [R]
- Diurnal rats lose about 30 percent of hippocampal capacity and perform far worse on spacial tasks after four weeks in dim light. [R]
- Workers near windows had higher melatonin levels and lower cortisol at night compared with workers who weren’t near windows. [R]
- Psychologically and physiologically unwell hospital patients seem to recover faster when exposed to sunlight. [R] [R] [R] [R] [R]
- In elderly patients with major depressive disorder, bright light therapy improved mode, sleep efficiency, and cortisol levels. [R]
What About Flicker?
We have to address flicker somewhere, so this is where we do battle.
We all know visibly flickering lights are undesirable. However, lights can flicker quite a bit past the point that we can perceive visually.
The question is, does that flicker matter?
If you peruse a website like ledstrain.org, you’ll see that there are definitely folks who seem to suffer in the presence of invisible light flicker. Perhaps they are the canaries in the coal mine?
I’m currently utilizing GE Sun Filled lights in my office, which we’ll go over in the light bulb recommendation section below. These lights flicker imperceptibly by about 12-15% at around 120-240 Hz.
Neither my girlfriend nor I have noticed any negative effects from this, however that doesn’t mean much, often imperceptably negative things are difficult to detect.
The IEEE has attempted to set an optional industry standard for flicker with Std. 1789. They looked at all the available data and created a rough guide for flicker.
IEEE Std. 1789:
- At frequencies below 90 Hz, maximum percent flicker = frequency x 0.025 [for example, at 80 Hz, the maximum percent flicker is 80 x 0.025 = 2 percent]
- At frequencies between 90 and 1250 Hz, maximum percent flicker = frequency x 0.08 [for example, at 250 Hz, the maximum percent flicker is 250 x 0.08 = 20 percent]
- At frequencies above 1250 Hz, no restrictions on the percent flicker. (Note: this is the minimum allowable frequency for basic pulse-width modulation (PWM)-based dimming.)
However, it should be noted that these are just best guesses at this time, as the science of invisible flicker is fairly understudied.
You can check just about any light source for flicker by filming it in slow motion with your smartphone. Any visible flicker equates to a flicker percentage of at least 5% within the 120Hz-240Hz range, depending on your phone’s capabilities.
- Reducing flicker: If you have any amount of AC line noise in your home’s electrical wiring, this can exacerbate flicker in resistive (incandescent) lights and, to a lesser extent, LED lights. You can place AC line noise filters, otherwise known as dirty electricity filters, in your outlets to help diminish this.
At the end of the day, invisible flicker is something you may have to deal with if you want full spectrum light in your eyeballs. That’s just the market right now, whether that’s worth it is up to you!
The Best Full Spectrum Light Bulbs
The only way to reliably mimic the visible portion of sunlight is with LEDs. Now you might be thinking, but Derek, LEDs suck. And you’d be right, except they don’t anymore.
Now, historically, LEDs obtained their “cooler” color with the dreaded big blue spike. However, newer LED phosphor technologies have made these classic LED problems a thing of the past.
What we’re left with instead is an impeccably realistic color spectrum, that feels natural and energizing!
Here are some of the current front-runners for full spectrum LEDs:
Unfortunately, the pickings are rather slim. Hopefully with time more companies and manufacturers get in on the full spectrum LED game.
But without further ado, the lights:
- GE Sun Filled: These are currently the best USA option, utilizing SunLike LEDs, the spectrum is just fantastic. The only downside to these light bulbs is that they have a 12-15% flicker rate at around 120Hz, which could potentially bother some people. NorbSmile is the only other SunLike option in the US, but their bulbs have worse flicker, and cost twice as much, so I can’t recommend them at this time. I’ve emailed both companies requesting that they improve their driver technology.
- Shanpu ZPro LEDs: I’m not sure which parent company produces these diodes, but they are, to my knowledge, the most realistic artificial visible light sources on the market right now. I can only find them on TaoBao, so you’ll have to go through a third party agent to get them shipped to you. I used SuperBuy to purchase mine for testing, but any TaoBao agent will work. Warning: They’re expensive, but you get what you pay for. It’s worth mentioning that these lights have better drivers and metal housings for better heat dissipation and will likely last much longer than the GE lights.
- Wala Light System: Walalight offers variable temperature control LED panels utilizing SunLike diodes. I’m not sure if these can be purchased for residential applications, I’ve reached out to them by email but got no response. But stuff like this is certainly the future of interior lighting. Being able to dynamically automate the temperature of your full spectrum interior lighting…*mwah chefs kiss*
- REMEZ Bulb: REMEZ is a Russian company who makes LED bulbs using SunLike diodes. The only place I’ve found them commercially available is a Russian website called ozon.ru, they claim to offer worldwide shipping, however I haven’t been able to purchase them as I don’t have a Russian phone number. Here’s a review of this light.
- LumiFlex700 Pro LED Strip: This is the only LED strip I can find using SunLike LEDs. They come in various color temps, and would be perfect for those of you with the means or desire to install cove lighting. I haven’t personally tested these for flicker.
- LEDVANCE Tunable Smart Lights: This one is for you Europeans out there. They use SunLike LEDs so that’s a plus; although I’m not a big fan of using EMF devices, that’s a personal decision for you to make. They are adjustable from 2200K to 5000K, which is a very cool feature for a light like this to have. However, at this time, I have no idea what the flicker rate or companion app is like.
- Full Spectrum Fluorescent Tubes: For those of you working for hours underneath fluorescent light ballasts, it might be worth talking to your maintenance guy about swapping them out if they’re old or too warm in appearance. Below are the best full spectrum fluorescent lights I could find. If you’re under these all day long, and you will be for the foreseeable future, it would be in your best interest to improve them.
How to Implement
Here are a few ideas for you to try out and customize to your spaces.
The DIY Chandelier
So probably one of the easiest ways to add full spectrum light to your office or room is with a chandelier, and more than one are often needed for adequate lux levels to be achieved.
- Mount one or two hanging ceiling fixtures, you can get this in white/black or hemp.
- Attach a 5-in-1 or 7-in-1 to these fixtures, depending on your room size or required lumens.
- You can also attach the extended versions to existing ceiling sockets if you have them.
- You’ll want your lighting to be as ambient as possible, so make sure these lights and fixtures are not in your FOV.
- Use Waveform’s lumen calculator to find out the total lumens you should shoot for based on the size of your room. I recommend using 100 fc as a starting point. My office is 9x11x8 ft, and I’m at around 13,000 lux and I could double that, so don’t be afraid to get bright. If the light is of a natural spectrum overall and isn’t directly in your field of vision, it will feel comfortable at high intensities.
- It’s up to you how much light you want, but if you go with two fixtures, you can always use just one in the morning and late afternoon and both during midday.
- Alternatively, you can utilize a dimmer, however, keep in mind that they will introduce RF into the environment if you’re mindful of that sort of thing.
- Additionally, with the 5-in-1 or 7-in-1 fixtures, you can place an A19 or BR30 halogen in the bottom socket to improve the ambient infrared in the room.
Another approach is to install ceiling mounted string lights. This gives you the ability to spread the light out over a larger surface area, making it less glaring to increase the total lumens in a room.
You’ll probably want to install and fill up two of these. You can include one incandescent or halogen per 6 or so bulbs to even out the visible spectrum with infrared.
Desk Lamp Options
Okay, so what about those of you who have a work office and want more light all up in those eyeballs?
Various lamps, extenders, and fixtures can be utilized to provide point of use lighting.
These kinds of setups can obviously risk introducing glare, meaning the light source stands out too much from the ambient light, causing discomfort. Getting the lights above eye level and further from your screen helps.
Even just one full spectrum BR30 pointed towards you during the day could have a really positive impact on your mood, sleep, and overall wellbeing.
- Desk and Clamp Lamps: Various lamps can be bought, some that sit on the desk, some that clamp to a desk, and some that can clamp to shelving or higher up objects.
- Accessories for Lamps: You may need or want some of these to create your lights.
My Office Setup
I figured I should share what I’ve done with my own office space:
- I’ve built two large DIY chandeliers with six GE Sun Filled bulbs and one 53w halogen each. Though I think I’d like to make another… This gives the room most of its lux.
- I also have a floor lamp with three halogen BR30s pointing towards me for more full spectrum infrared exposure, it gives off a pleasant warmth at around two feet.
- And finally, I have a 48″ UV reptile light mounted to the corner of my ceiling molding, spraying the room with a trace amount of UV light.
Here’s what I’ve ended up with:
And here’s what the spectrums look like in there:
Not bad eh?
Replicating Full Spectrum Infrared Light
The next step in our replication of sunlight is to bring infrared back into the game.
Infrared light is of course very famous right now as red light therapy and is useful for a number of reasons. However, most of us go entire days without getting any IRA or B on our skin, and this is no good.
The Science Behind Full Spectrum Infrared Light
Why is infrared light so beneficial and necessary?
- Red and infrared radiation penetrate deepest into the body, and help mitigate the stress response from short wavelength blue, violet, and UV exposure. [R]
- Morning exposure to red light improves eyesight in older people, afternoon exposure however did not seem to have the same effect. [R]
Now, technically, the Sun contains a bit more IR-A than IR-B, and very little IR-C. While tungsten fillament bulbs contain proportionatly more IR-B and IR-C than the sun.
The image below shows the general curve trend of sunlight compared to a tungsten filament lamp.
What the image above is missing is the absorption bands of water. Becasue as sunlight passes through the atmosphere, water droplets in the air absorb much of the infrared.
So, if you want to get really nerdy, you have to filter your infrared with water. What you’re left with is called wIRA or water-filtered infrared A.
This kind of infrared is used medically, as the smaller amounts of IR-B and IR-C prevent the skin from overheating, and allow for higher doses of IR-A which penetrate much deeper into the skin.
It is of course at this time impossible to purchase such a device commercially that accomplished this, nor is it reasonable to put throughout ones home.
Once I have something to report on a DIY HydroSun, you’ll be the first to know!
If you sign up for my newsletter that is.
But for now, I think regular old halogen is gonna be okay.
The Best Infrared Lights
The best way to get healthy full spectrum infrared in your home or office is with tungsten filament bulbs like incadescents or the slightly more advanced halogens.
Here are a few options:
- GE A19 Halogen: These are a great addition to a DIY chandelier if you’re looking to add some more red and infrared to your full spectrum LED bulbs.
- Incandescent R40 Heat Lamp: These can be used in larger areas like kitchens or family rooms to give the space more natural infrared energy.
- SATCO BR30 Halogen: These are a great option if you’re looking for a little more directed infrared in sockets that can’t accept powerful lights. These are 65w so if you’re using a 60w rated lamp you may feel more comfortable with the option below. However, as long as they aren’t enclosed in any way, and you’re in the room while they’re on, I wouldn’t be too worried about the 5w difference.
- 60 watt BR30 Halogen: An alternative to the option above for sockets rated at 60 watts max.
How to Implement
Here are a few ideas for you to try out and customize to your spaces.
The Three Arm Lamp
One option I really like at my desk is this lamp:
The Desk Lamp
Of course, if you can’t pull off the three arm lamp where you work, there are alternatives. Both of these setups are discussed above in the visible light section.
The Big Boy
For larger areas, and for a bit more throw, you can use high wattage heat lamps.
Replicating the Ultraviolet Spectrum
Finally, we have ultraviolet light, and yes, it too is an important part of sunlight! Believe it or not, both UVA and UVB penetrate the atmosphere all year, even in high latitude areas in the winter.
The reason it’s often said that you can’t make vitamin D in the winter is just because there’s much less UVB, and you’re always wearing clothes. But it’s still there.
The Science Behind Ultraviolet Light
Our bodies have adapted to utilizing UV radiation for a very long time.
We of course need UVB and UVA to make vitamin D in the skin, as well as some other things, so I think it’s a good bit of common sense to put a healthy amount of UV in our homes.
As I mentioned earlier in the guide, natural sunlight gets as strong as around 20:1 UVA to UVB, so we’ll want to try to match that the best we can.
The Best Ultraviolet Lights
The best UV lights are currently fluorescent in nature, LEDs that produce wide spectrum UV are recently gaining a bit in the reptile space, so it might not be too long before we see decent LED options, they just aren’t here yet.
And so fluorescent it is.
Fluorescent lights contain trace amounts of mercury and other toxic metals. Be careful not to break them, and if you have children who throw things, you may want to purchase a cage for your light.Safety Warning
- Arcadia 6% UVB Lamp: This is probably one of the best UV lighting options out there currently. It provides a ratio of 5:1, which clearly isn’t 20:1, but at a low UV index I don’t really see this being a huge deal, I would certainly consider it better than no UV at all. The ballast used in the Pro T5 Kit is a high frequency electronic ballast, so there’s no flicker and very low EMF exposure, unlike the old magnetic ballasts some of you may be familiar with.
How to Implement
The best way I know of to add ultraviolet into your indoor space is by mounting a T5HO tube lamp in the corner of a rooms’ ceiling.
These can be added to any number of rooms where large amounts of time are spent.
TIP: Flourescent UV bulbs should be replaced every year or so, as the UV output fades with use.
The UV index for this light setup is as follows:
1 ft: 3.5 UVI
2 ft: 1.5 UVI
3 ft: 0.8 UVI
4 ft: 0.5 UVI
5 ft: 0.2 UVI
Here’s a collection of various tools for measuring your light environment, before moving forward, you may want one or two of these.
- Solarmeter Model 6.5 UV Index Meter: You’ll probably want one of these if you plan to incorporate a UV bulb into your sunlight spectrum setup. This way, you can ensure you won’t be exposed to unnaturally high levels of radiation.
- Handheld Digital Light Meter: This is a fun tool to have on hand if you’re looking to emulate the brightness of the sunlight in your area. It’s also just a fun tool for curious minded folks.
- Handheld Light and Monitor Calibration Meter: If you can spend a bit more, this meter will measure flicker rate in addition to the lux.
- Sekonic Spectrometer: If you’re feeling extra wealthy and scientific, this meter will allow you to measure the visual spectrum from 380 to 700 nm as well as the CCT, CRI, TM-30, and lux, as well as some other color rendering properties.
TLDR: Action Steps
This section is for those of you who either don’t have time to connect all the dots above, or just want a quick list of things that can be done to optimize your biology.
- Ensure that the indoor environments in which you spend the most time have adequate circadian light, i.e. >500 total lux, ideally >1000 lux. This can be done with any lux meter.
- Purchase full spectrum LED light bulbs of 5000K or greater for daytime use in your home and office, and purchase or create fixtures that will allow you to achieve a high level of lux. GE Sun Filled are a great option.
- Setup full spectrum infrared lighting by using either incandescent heat lamps or BR30/A19 halogen bulbs.
- Bring healthy UV into your space by mounting a reptile T5 fluorescent light in your most occupied area(s).
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