Blue light is on the lower end of the visible light spectrum; it is also referred to as High Energy Visible (HEV) light. The visible light spectrum, as shown below, sits between Ultraviolet at the low end and infrared at the high end.
The blue light that we hear so much about these days falls within the range between 380 -460 nm. Harmful blue light rests right around 435nm.

There are many sources of blue light: electronic devices such as cell phones, tablets, laptops, computer screens, as well as fluorescent and LED bulbs. But the largest source of blue light is one that everyone encounters on a daily basis: the Sun! Well, almost daily. Those that live in the great PNW might not see the sun every day, but we still feel effects from its light source.

Blue light from the sun is partly responsible for keeping our circadian rhythms in balance. When the sun goes down, and we stop receiving that blue light signal, our bodies then know that it’s time to prepare to sleep. (Is this why I’m so much more tired feeling in the winter? Hmm…) So when people use electronic devices close to bedtime, they disrupt the body’s natural rhythms, making it harder to fall asleep. They are tricking the brain into thinking it’s still daytime! This also suppresses the secretion of melatonin, a hormone produced at night that prepares us for sleepy time.

Not only can disrupted sleep patterns make us grumpy, they also increase our risk of obesity and depression. Along with obesity comes diabetes and heart disease. Yikes!

If that weren’t enough, extended exposure to a harmful blue light- emitting devices can produce Computer Vision Syndrome or Digital Eye Strain. Symptoms include blurry vision, difficulty focusing, dry and irritated eyes, headaches, neck and back pain. Digital eye strain has overtaken carpal-tunnel syndrome as the number one computer-related complaint!

A few precautions you can take to reduce your exposure to harmful blue light:
1. See your eye doctor and ask about blue-light blocking lenses for both indoor and outdoor wear.
2. To reduce the symptoms of Digital Eye Strain, use the 20-20-20 rule: Every 20 minutes, take just 20 seconds and look 20 feet away.