Do you ever feel like your body thinks it’s daytime when it’s actually nighttime? Do ever feel amped at night, have trouble sleeping, have depression or other chronic health issues? Read on to see how your modern indoor lighting may be impacting your health!

Many of our body’s biochemical reactions are intimately linked with light exposure, with our cells often using light as a catalyst and calibration tool. This topic is called photobiology and it is the study of how living organisms are impacted by light. Our bodies are in a near-constant conversation with the sun in order to accurately calibrate our hormones with the correct circadian timing of a 24-hour light cycle. This is why it is key for us to understand how artificial light in our homes and offices may also be impacting our health through these very same pathways.

SUNLIGHT EXPOSURE AND HORMONE BALANCE

When we wake up, go outside, and get exposed to certain infrared and UV wavelengths of sunlight in the early morning, our bodies release different hormones based on the sun’s spectral signature vs. when we get exposed to late morning or midday sun with both UVA and UVB shining down from a higher angle with full-spectrum sunlight. The same is true when our bodies sense the specific wavelengths that occur with the late afternoon sun exposure, and finally, the information our bodies receive with a lack of sunlight in the evening and nighttime. All of our hormonal processes are at least partially reliant on what spectrums of light the sun is transmitting at different times of the day. See the table below showing how the spectral patterns are predictably different at various times of the day and also with different weather conditions.

This constant hormonal programming our bodies receive from the circadian rhythms of the sun is very cool, but unfortunately, these same receptors in our skin and eyes are also sensitive to artificial light at night. This can result in our bodies thinking that it is daytime at night! This blog is focused on explaining how the lighting in our homes and workplaces may be impacting our health and which lighting options are less detrimental.

WHAT IS ARTIFICIAL LIGHT?

Artificial light is light of any kind other than sunlight, moonlight, or firelight. All types of artificial light disrupt our hormones. I’m not suggesting we sit in complete darkness once the sun has set, I am merely pointing out that there are varying degrees of hormonal disruption depending on the type of lighting used. Fortunately, we still have access to some minimally invasive choices. But first, let’s define the two categories of artificial light, analog and digital, and what the differences are.

ANALOG VS DIGITAL LIGHTING

ANALOG: Analog lighting is any heat-based light source. Natural sources of analog lighting would be the sun and firelight. For artificial analog lighting, both incandescents and halogen bulbs fit the bill. The heat from these bulbs comes in the form of infrared as well as red and purple wavelengths. These heat-producing wavelengths more than balance the blue wavelengths present in these bulbs and some consider the exposure to a higher ratio of infrared and red wavelengths to be healing to the body. Many companies have recently come out with red light and infrared therapy beds, panels, and saunas.

DIGITAL: LEDs, compact fluorescent (CFLs), and fluorescent bulbs are considered digital lighting because they lack a higher ratio of red and purple wavelengths compared to blue. Because of this, these bulbs run cool and are considered not heat-based light sources. If you were to touch your hand to any LED or fluorescent bulb, you would notice a distinct lack of heat compared to the same brightness in an incandescent or halogen bulb. LED bulbs (even warm orange-looking Edison LEDs) have a very high ratio of blue wavelength light compared to any analog sources. These vintage LED bulbs simply employ a filter over the diode, however, the filter does not change the wavelength that reaches our eyes, despite its warm appearance. This means that we are still getting a large amount of blue light from any type of fluorescent, CFL, or LED; even if they have a warm kelvin rating and appear orange. See the chart below.

Note the high levels of blue vs the amount of red wavelength in the LED and Fluorescent spectral signatures. Notice the sunset signature has red and purple wavelengths as highest, which most closely matches the incandescent bulb signature. This is w… — Note the high levels of blue vs the amount of red wavelength in the LED and Fluorescent spectral signatures. Notice the sunset signature has red and purple wavelengths as the highest, which most closely matches the incandescent bulb signature. This is why I choose incandescent bulbs to light my home in the evening. As the evening progresses, I even dim my incandescents and sometimes use candles to continue to mimic the natural progression of dimming light at night for my hormonal health.

BLUE LIGHT & MELATONIN IMPACT

Now that we know digital lighting of any kind emits much larger amounts of blue light than red, let’s discuss why this matters in relation to the hormone melatonin. You may have heard about, or even participate in, the recent trend of blocking blue light at night by wearing (undoubtedly dorky) red or orange lenses over our eyes, and using night mode on our phones or IRIS on our laptops or computers. This trend was sparked by studies that showed the retina’s melanopsin sensors can reduce or restrict the release of melatonin if they encounter high blue light environments (or truth be told, ANY blue light wavelengths after dark.)

An article from science daily explains “…exposure to blue light significantly reduced the production of melatonin, whereas exposure to red light showed a very similar level of melatonin production to the normal situation. The researchers explain that the impaired production of melatonin reflects substantial disruption of the natural mechanisms and the body's biological clock. Thus, for example, it was found that exposure to blue light prevents the body from activating the natural mechanism that reduces body temperature. "Naturally, when the body moves into sleep it begins to reduce its temperature, reaching the lowest point at around 4:00 a.m. When the body returns to its normal temperature, we wake up," Prof. Haim explains. "After exposure to red light, the body continued to behave naturally, but exposure to blue light led the body to maintain its normal temperature throughout the night -- further evidence of damage to our natural biological clock." SOURCE

This happens because evolutionarily, as humans blue light wavelengths were only encountered during daytime and so our bodies think that we are many hours away from needing melatonin. A lack of melatonin release in the evening makes it difficult to sleep. Proper melatonin secretion indicates good circadian health and provides integral brain detox functions and encourages apoptosis of cancer cells (not something you want to avoid!) SOURCE

BLUE LIGHT RESULTING IN “CHRONIC JETLAG”

This image shows the mouse on the right with a larger tumor due to chronic jetlag from a chronically disurpted circadian rhythm vs the mouse on the left with a regular circadian rhythm and a smaller tumor.

The blue light debacle is relatively new due to the fact that for most of our evolutionary existence, blue light was only present during daylight hours, with the highest amounts naturally occurring in midday. Having any amount of blue light past sunset is wildly unnatural. Blue light at night time results in our bodies often releasing hormones that would be more appropriate for midday activities, except it’s closer to the middle of the night. This occurrence has been dubbed a “circadian mismatch” or “chronic jetlag” and it happens when external triggers such as artificial lighting, food consumption at odd hours, or unusual temperature shifts indicate that it is one time of day when it is really another. This causes our bodies to become out of sync with the actual time of day and creates internal mayhem with what would otherwise be a very elegant system. Issues like insomnia, anxiety, blood sugar instability, hormone imbalances, temperature dysregulation, cancer (specifically breast and prostate Source), and more can occur if a circadian mismatch is present for months or years, leading to chronic inflammatory and degenerative states. Source.

For tips on blacking out your bedroom at night to preserve your melatonin, see my blog post about it here: BLACKING OUT YOUR BEDROOM FOR HEALTH: THE DARK SIDE OF LIGHT

INVENTION OF THE LIGHT BULB

Let’s rewind back to when the incandescent lightbulb was invented: 1864. The 1860s are admittedly a very recent era when compared to our species’ entire existence on earth. To put it in perspective, we’ve only had artificial light for about 4-5 generations total. Before the 1860s, we solely used firelight at night by burning kerosene, whale blubber, animal fats, vegetable oils, coal, wood, or wax candles. But no matter what you burned, it was all firelight. You may ask yourself, doesn’t firelight disrupt hormones as well? Turns out no! Firelight; miraculously, has been shown to not disrupt any hormone signaling at night. This is a pretty spectacular finding, and one I can only rationalize due to the fact that we evolved sitting around firelight in the evenings for many thousands of years prior, and one could even argue that there may be medicinal benefits of firelight’s infrared wavelengths on our bodies post sunset.

However, when the lightbulb came on the scene and we were able to have simple, non-flammable artificial light at night, it felt like a complete miracle. We did not understand that the incandescent lightbulb emits different wavelengths than firelight. Not nearly as different as digital lighting, but it was the first time any amount of blue wavelength light was experienced indoors after dark. It would be hundreds of years before realizing that our skin and eyes have receptors that are incredibly sensitive, and incredibly powerful at signaling our brains to release, or restrain, certain hormones based on the type of wavelengths of light they receive at any given time.

MIXED SIGNALS

Artificial light at night sends our bodies mixed signals, which are very confusing. Sleep with the TV on? Your body thinks it’s solar noon all night. Use LED lights at night in your home. Same thing; the blue light present in these bulbs is telling your body it’s practically noon, so you better make the hormones you need to stay alert and active for another 9 hours. Pretty radical, yet quite obvious once you understand melanopsin, neuropsin, and where these receptors reside: in the retina and skin of every surface of the human body. The effect of artificial light can have a huge impact on melatonin in 99% of people. Source But how about testosterone? Estrogen? Serotonin? Dopamine? All of these hormones are partially regulated by sunlight and are impacted negatively by artificial light. Source It’s hard to overemphasize how global an issue this is for our species from a wellness perspective.

BLUE LIGHT & MACULAR DEGENERATION

There are studies that blue light in the absence of higher amounts of red and purple wavelengths (think LEDS and fluorescents) causes macular degeneration due to an overstimulation of the rods and cones through our melanopsin receptors in the retina. This causes a high rate of reactive oxygen species to be produced without the red spectrum to trigger mitochondrial cell repair. This leads to irreparable damage to the retina and worst case will eventually result in blindness! Source

ARTIFICIAL LIGHT & OBESITY

A Harvard study shed a little bit of light on the possible connection between diabetes and obesity. The researchers put ten people on a schedule that gradually shifted the timing of their circadian rhythms to later and later. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, decreased, which leaves people more susceptible to overeating. Another study linking chronic light exposure at night with increased insulin resistance has also come about. Source

USING INCANDESCENT BULBS FOR LIGHTING AT NIGHT

I know going back to incandescent bulbs is not ideal from a financial perspective; they use more energy. However, if you are strategic with placement, you only need a few in each room. I have noticed if I use them overhead in a lantern or pendant light, they shed more light than in a desktop lamp. I currently use 40-watt clear glass incandescent bulbs found here. Using the clear glass bulbs vs the ones that are cloudy will give you more exposure to the healing infrared wavelengths. These bulbs still have more blue than firelight. Firelight has the warmest rating which comes in around 1800 degrees Kelvin while the warmest tungsten bulbs available are usually in the 2400-degree range. The higher the number the more blue light a bulb contains. Sunrise is around 2000 degrees Kelvin and already has some blue light in it in order to start waking your brain and body up! To get around this issue, I still wear blue blocking glasses while using my warm incandescent bulbs at night.

USING CANDLELIGHT FOR LIGHTING AT NIGHT

If you want to be a circadian rhythm perfectionist, then going back to full firelight at night would be the choice. I’m not there yet, but who knows, maybe one day! I gleaned some insight from a friend who grew up overseas using candlelight exclusively at night and she shared tips about how her family made the most of their candles. If you want to purchase your candles, instead of making them at home, I prefer Big Dipper Wax Works, due to their clean ingredients and burn. Enjoy!

Use container candles and lanterns for extra fire protection, especially in windy environments
Do not leave burning candles/fires unattended
Use beeswax candles with cotton metal-free wicks for the cleanest burn. Soy, paraffin, and other scented candles release pollutants into the air and should not be used, especially in enclosed environments. I know beeswax is more expensive but please read more about air quality before choosing a cheaper alternative.
Use mirrors behind your candles to reflect more light into the room.
Group candles together in areas where you need more light.
Burn candles for at least as long as they take to melt to the exterior of the candle. This will prevent the tunneling of the candle and be the most efficient use of your wax.
Store beeswax candles in the freezer before use for a longer burn.
Taper candles produce the most light.

PRECAUTIONARY PRINCIPLE

In the US, candlelight, or incandescent bulbs, might be things only the Amish employ past sunset, but I’m here to tell you we may consider going back, en masse, as more studies scrutinize the health effects of digital light sources such as LEDs and fluorescents. Until the science is clear, I’ll be on the precautionary side of things and exclusively using clear glass incandescent bulbs and candlelight in my home after sunset.

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Lighting Your Home + Office For Health