What is blue light?
Blue light is a high-energy visible light with a wave length between 400 and 450 nanometers (nm).
From a natural source, such as the Sun, the shorter, high energy blue wavelengths collide with the air molecules causing blue light to scatter. This is what makes the sky look blue.
Artificial blue light comes from light-emitting diodes (LEDs), often used in energy-efficient light bulbs, as well as the lighting in our electronics, laptops, phones, TVs, tablets – anything powered by electricity likely has blue light.
Artificial blue light is quite different from blue light received from a natural source (like the Sun) as part of a balanced light spectrum. Although an LED bulb and an incandescent lamp might both be rated at the same brightness, the light energy from the LED might come from a source the size of the head of a pin compared to the significantly larger surface of the incandescent source. Looking directly at the point of the LED is dangerous for the very same reason it is unwise to look directly at the sun in the sky.
Sources of Blue Light Exposure
Most of us are exposed to much more blue light that we realize. Sources include:
Sunlight (the biggest source)
Electronics like TVs, phones, tablets and computers
Light bulbs and other sources of artificial lighting: fluorescent light, compact fluorescent light bulbs and LED light (LED bulbs are especially harmful)
Blue light at night messes up your circadian rhythm
Research has demonstrated that nighttime light exposure suppresses the production of melatonin, the major hormone secreted by the pineal gland that controls sleep and wake cycles.
Do you remember when nighttime lights were a cosy hue of amber and orange?
Until 1879 when Thomas Edison patented the electric lightbulb, artificial lighting didn’t exist and after sunset, people relied on candles, lanterns, and fires for light. Blue wavelengths of light that are absent in light sources like candles, lanterns, and fires.
Today’s new lighting tech in LEDs have almost nothing BUT blue wavelengths of light. In many countries, night street lights that were once orange-coloured emissions from older sodium lights are rapidly being replaced by white-coloured emissions produced by LEDs.
Local LED street lighting has dramatically reduced even nocturnal insect populations.
The lower your melatonin levels, the greater your risks of cancer.
Blue light at night ruins your sleep
30,000+ cells in the eye sense blue light and these cells signal the pineal gland to suppress the secretion of the hormone melatonin. Melatonin is necessary for sleep, and when it is suppressed at night, when it should be increasing, it literally affects yoru sleep quality.
Light at night is part of the reason so many people don’t get enough sleep,
blue light can cause immune issues
A study found a direct link between blue light exposure and an increased risk of breast cancer and prostate cancer. People exposed to high levels of outdoor blue light, like street lights, at night had a higher risk of developing breast cancer and prostate cancer, compared with those who were less exposed.
Blue light can cause diabetes
A Harvard study looked at the connection of blue light at night to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. 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, went down.
Quality light is life
The light you live in is directly related to your quality of life.
that light and sleep are two of the most under-used tools for improving health (and that improper management of both are two of the biggest reasons for many health problems)
References & Resources
Towns and cities reversing their decision on LEDs to mitigate the harmful impacts on health and ecology https://www.theguardian.com/uk-news/2023/mar/19/good-heavens-north-yorkshire-village-hawnby-switches-to-dark-sky-friendly-lighting
10 ways to protect yourself from blue-light exposure and melatonin suppression