The visible light spectrum contains all the colors of the rainbow. At one end of the spectrum are the red shades. These have the longest wavelength and the least amount of energy. At the other end of the spectrum are the blue shades. They have the shortest wavelength and the most energy. All the colors together create white light or sunlight.
Blue light is found naturally in sunlight. When the blue wavelength collides with air particles and water molecules, the light scatters creating the blue color seen in the sky. It is the blue light from the sun that regulates our circadian rhythm, our natural sleep and wake cycle. It also boosts alertness and reaction time, elevates mood, and increases our sense of well-being thereby preventing depression and seasonal affective disorder.
Blue light is also found indoors in manmade devices like fluorescent and LED lighting, flat screen TVs, tablets, laptops, desk top computer screens, and smart phones. It is these artificial light sources that can have a negative effect on our health.
The blue light from these devices can disrupt our sleep. It can suppress our delta brainwaves needed for sleep; it can disrupt our sleep wake cycle by keeping us alert at night; and it interferes with REM sleep (when we dream). Blue light also suppresses melatonin which is the hormone that signals sleep. A University of Toronto study found that night shift workers who wore “blue light blocking” glasses produced more melatonin than those who didn’t. Other scientists have compared 6.5 hours of exposure to blue light vs green light. Their results showed blue light suppressed melatonin production about twice as long as green light–3 hours vs 1.5 hours.
In addition to sleep issues blue light can also cause other health problems. Its shorter wavelength causes it to flicker more easily than other colors. This flickering creates glare and can reduce visual clarity. It can also cause eye strain, headaches, and fatigue when sitting in front of electronic devices for too long. Spending as little as two consecutive hours in front of these devices can cause eye strain. Virtually all blue light natural or manmade reaches the retina; the eye has no natural filter for it. Blue light exposure is believed to increase the risk of macular degeneration. Lastly, Harvard researchers have specifically linked night shift work plus exposure to blue light at night with breast and prostate cancer, diabetes, heart disease, obesity and depression.
What can you do?
- Stop using electronic devices 1-2 hours before bed
- Dim lights before going to bed
- Blue light blocking glasses can be worn when using electronic devices
- A “blue light filter” coating is available for prescription eyeglass lenses
- Check computer settings to filter blue light on device screens
- Check smartphone setting under Display/Brightness for a blue light filter
- There are also Apps available to block blue light
- Some Device Filters include: F.lux, RetinaShield, iLLumishield, Eyesafe