Blue Light Isn't Bad—But Out of Coherence, It Is

I recently watched a YouTube video that claimed all blue light is harmful to health. Little do they know the blue light found in the sun, balanced with red and infrared light, only available during the daytime, is very different from the single-spectrum blue light found in electronics, available 24/7 and with no seasonal variance. One of these lights is man-made, and one is nature-made. Which one do you think your biology is built for?

This brings us to an important question: Does the introduction of artificial blue light at night impact our health?

Almost certainly.

What Is Blue Light and How Does It Affect Sleep?

While commonly used in modern lighting and screens, isolated blue light can negatively impact sleep and, therefore, our health. This is not a debated concept, the research is readily available.

Before artificial lighting, the sun was the primary source of light. Nights were spent in relative darkness or by the fireside, with its rich infrared (IR) light emission. Modern technology has introduced widespread artificial illumination, which has altered our natural circadian rhythms. Research suggests that nighttime light exposure disrupts sleep and contributes to various health concerns.

The sun contains multiple wavelengths of light and presents it in a way that is consistent with evolution and in a way that supports our biology. We do not see these wavelengths, we just see illumination, but it really is a bunch of different light frequencies changing seasonally and daily that illuminates the world we see. 

The visible light spectrum is the distribution of wavelengths of light radiation, or those that we are able to recognize with our eyesight. The range of human visible light is roughly 380 to 780 nm. This range is received by our eyes, but other animals can register radiation of other lengths.

How Blue Light Influences Your Circadian Rhythm

Through an evolutionary lens, we evolved to use the sun as a clock. Just because I know it's 9 AM doesn’t mean my body knows it’s 9 AM. My body senses time through its environment, specifically the light that shines on my skin and eyes.

So what happens when we trick our body into thinking it's daytime when it's actually night by exposing it to bright artificial single-spectrum blue light? What happens when our circadian rhythm is disconnected from nature?

Light exposure at night, (and incorrect light exposure during the day), can interfere with the body's internal clock, known as the circadian rhythm. This disruption leads to poor sleep and is linked to potential health risks, including metabolic disorders, cardiovascular disease, and obesity. Cyan, or sky blue wavelengths, which enhance alertness and mood during the day, appear to be the most disruptive after dark. The increasing use of electronic screens and energy-efficient lighting has significantly raised our exposure to isolated blue light, especially in the evening.

How Does Light Impact Our Sleep Biochemically?

Melanopsin, the main photoreceptor responsible for suppressing melatonin production, is highly sensitive to light exposure in the cyan range. Even dim lighting can reduce melatonin levels and disturb sleep patterns. A single photon of light becomes amplified in the retina and can cause false signaling. Studies have shown that this melanopic blue/green light in the cyan range suppresses melatonin more effectively than other wavelengths, leading to shifts in circadian timing. 

Research comparing blue and green light exposure found that blue light delayed melatonin production for nearly twice as long. This lack of melatonin raises cortisol levels, which can further impact sleep quality and overall health.

In the 1700s, Swedish botanist Carl Linnaeus planted a flower clock, a garden where flowers open and close at specific times of day in response to the changing intensity and wavelengths from natural sunlight, letting you tell time just by looking at them. Nature as a watch? Genius.

Our biology works the same way. We are intimately tied to nature and the light of the world just like animals and plants. Only we have forgotten.

The Debate Over LED and Fluorescent Lighting

As society moves toward energy-efficient lighting solutions, concerns arise about the effects of LED and fluorescent lights, which emit significant amounts of harsh dark blue light, unbalanced by red and infrared light. The cost of energy efficiency is charged to our health. 

While adjustments to coatings inside bulbs can create a warmer tone, most modern lights still contribute to blue light exposure in the evening.

How to Reduce Blue Light Exposure at Night

To enhance sleep and the repair processes that occur during, you need to ensure you have a lighting system which supports optimal health. This includes turning off the bright dark blue rich LED lights and opting for more circadian appropriate lighting system

• Use dim amber or red lighting at night, as it has minimal impact on melatonin levels.
• Limit screen time two to three hours before bed or use blue-light-reducing settings, apps and glasses.
• Wear blue-blocking glasses such as Nighshades, if you need to use screens or are in brightly lit environments at night.
• Increase exposure to bright light during the day, this strengthens circadian rhythms and promotes better sleep.

Links: Blue light blockers (Nightshades)