• Blue Light and Your Circadian Rhythm

    You’ve probably been told at some point in your life that being in the presence of light during the night will agitate your body’s circadian rhythm (your natural internal clock). Exposure to light during nighttime hours will reduce the amount of melatonin (a hormone that helps you to sleep) that your body produces. What many people don’t realize, however, is that blue light is usually the largest culprit of melatonin suppression, and is therefore heavily linked to sleep deprivation.


    You can’t exactly avoid blue light; blue light is everywhere. When the light from the sun — which contains a varied spectrum of colored light, including blue light — travels through our atmosphere, the shorter, higher-energy wavelengths collide with air molecules, which causes blue light to scatter in all directions. This deflection of blue light waves is what causes the sky to appear blue. Your body uses natural blue light from the sun to regulate your circadian rhythm, which includes your sleep cycles. Blue light can also have positive effects on your mood, increase alertness, accelerate reaction speed, and generally promote a feeling of happiness.


    Because blue light is so bright (and often aesthetically pleasing), it is widely used on the screens of cellular phones, tablets, computers, and televisions. Because of its widespread use, blue light appears to be causing problems for our eyes, on melatonin, and consequently, on our health.

    Exposure to light of any wavelength can suppress an individual’s secretion of melatonin. The effects of blue light, however, are far more dramatic in this regard, relative to other colors of the visible spectrum. In 2012, Harvard researchers conducted a study analyzing the effects of prolonged exposure to blue light versus exposure to green light of similar brightness. Results showed that blue light suppresses melatonin for approximately twice the duration of green light, and altered circadian rhythms by twice as much (3 hours vs. 1.5 hours).

    Another study conducted by researchers at the University of Toronto found that blocking incoming blue light with tinted glasses or goggles prevents melatonin suppression just as well as dimming the lights altogether.


    Aside from disrupting your circadian rhythm, unnatural blue light has been linked to numerous negative effects on your health:

    • Blue light can damage your eyes. Blue light has been found to cause damage to retinal cells, and can increase the risk of age-related macular degeneration.
    • Blue light is considered a “carcinogenic pollution” that may correlate with higher cancer rates.
    • Suppression of melatonin can lead to depression and anxiety, and has also been linked to diabetes, heart disease, and obesity.
    • Blue light promotes digital eye strain, and can cause headaches and temporarily blur one’s vision.


    Has exposure to blue light affected your vision? Do you suspect your electronic devices may be keeping you up at night? Contact Silverstein Eye Centers today at (816) 358-3600 or request your appointment online. We can serve you at our convenient location in Independence/Kansas City.

    Posted November 17, 2015 by Silverstein Eye Centers
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