Light is made up of particles that travel as waves of energy. These particles range in both length and strength depending on where they fall in the spectrum. Wavelengths of light are measured in nanometres (nm). Some are visible to the human eye, such as the colours red, orange, yellow, green, blue, and violet. Others are invisible, such as infrared and ultraviolet.
Blue light is a colour in the visible light spectrum and falls within the 400-500nm range. As shown in the diagram below, each wavelength range represents a different colour.
Blue light in the range of 400-450nm is a very short and strong wavelength. This type of light can cause eye damage, like macular degeneration, due to its ability to penetrate the retina in the eye.
Blue and green light ranging from 450-550nm has a direct effect on the the brain's ability to produce melatonin, a hormone very important for sleep and overall health and wellbeing.
Melatonin, also know as the sleep hormone, is produced by the pineal gland in our brains. Melatonin is responsible for regulating sleep and wakefulness.
After the sun sets, a signal is sent to the brain to start secreting melatonin, which in turn causes sleepiness and eventually sends us into a deep and restful sleep. Exposure to artificial blue light at night completely messes up this elegant process of priming you for sleep. Blue light at night suppresses melatonin due to the signals it sends to your brain. This tricks the brain into thinking it’s the middle of the day regardless of the actual time. Your brain then responds by making you feel more awake and alert.
Today, we are flooded by blue light all of the time. We carry artificial suns in our pockets. Every time we look at our smartphone or tablet or turn on lights, we send a signal to the brain that the sun is up. In modern society, once the sun goes down, we watch our favourite TV shows, go on social media using our smartphones, and turn on our lights in our home, all of which produce very high amounts of artificial blue light. This chronic exposure to blue light—even if it’s only low blue light—at night is suppressing melatonin and robbing you of precious sleep.
Blue light exposure at night is impacting our circadian rhythm, sleep, and overall health.
The problem with modern devices, such as phones, LED light bulbs, TVs, and other forms of energy efficient light, is that they put out a large amount of light in the blue spectrum. You can see in the image below how various light bulbs have different levels of blue light and how they affect melatonin (the sleep hormone).
Not all blue light is bad for us. Blue light can be found both in nature (from the sun) and artificially (from LED lights, screens, phones etc). When you go outside, you are exposed to natural blue light emitted from the sun. In the morning, when we are exposed to sunlight, the light sends a signal to our brain that the day has begun and that it’s time to start feeling awake and alert.
Natural blue light is different in that it is always delivered with the rest of the spectrum and balanced out by a proportionately large amount of infrared, red, yellow, orange, and UV wavelengths, which is what we call a full spectrum light. The proportions of the different colours also vary throughout the day, e.g. less blue and more red and infrared in the morning, more blue and UV at midday, and then back to higher amounts of red and infrared at sunset. In modern artificial lighting, blue is predominant, delivered in spikes, and completely lacks the full spectrum of light.
Getting healthy doses of blue light from the sun is essential to setting your circadian rhythm and regulating your sleep and wake cycles.
Blue light from the sun has also been shown to improve alertness, mood, and motivation. Getting adequate amounts of natural blue light is essential to maintaining overall health and wellbeing.
Our body clocks are trained and set by the presence of blue light, or lack thereof. In the morning, when blue light from the sun enters our eyes, it sends a signal to our brain that the day has started and it’s time to feel awake, alert, and full of energy. After the sun sets and it becomes dark, the lack of blue and green light in our environment tells our brain that it’s time to wind down, so it releases melatonin, making us feel relaxed and sleepy and allowing us to obtain deep and restful sleep.
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