In our previous newsletter, we mentioned how harmful blue light is to the retina because it packs a lot of energy and contributes to the development of macular degeneration. Before we had high definition LED computer/device screens and televisions, we were not significantly exposed to blue light in the evening or indoors. While there was some exposure from fluorescent light bulbs, they lost their popularity in the home in the 1970s and were predominantly replaced by incandescent light bulbs that did not emit blue light. In recent years, indoor exposure to blue light has been increasing, due to light emitting diodes (LEDs).
This new LED technology rapidly proliferated- first into our light bulbs, then into our computer monitors, laptops, and high definition televisions, and now into our smartphones (iPhones, Androids) and tablets (iPads, Kindles). Within a decade, we have gone from a society that was minimally exposed to indoor blue light to a population that is exposed to it at least 3 to 4 hours a day. Even more alarming is that nighttime blue light exposure is greatest in the younger generations, which prevents them from obtaining the appropriate amount and quality of sleep.
How Can Blue Light Affect Sleep?
In the retina, there is a receptor specifically atuned to blue wavelength light that connects directly to our brain’s pineal gland. The pineal gland is our internal biological clock that regulates our sleeping cycle. It is like a traffic light that tells us when to stop (Sleep) or go (Wake up). The actual stop light or sleep signal is a hormone produced by the pineal gland called melatonin. The go (wake up) light is actually blue light. Blue light is our body’s signal to wake up and shut down the production of melatonin in the pineal gland. The way to change the light back to the stop signal is by blocking the retinal exposure to blue light.
Lacking an indoor blue light source, our ancestors never had to block indoor blue light exposure. During the night, there were no sources of blue light to block melatonin secretion. Only in the last 2 to 3 decades has nighttime blue light exposure proliferated. This increase in nighttime blue light exposure has caused an increase in insomnia and sleep disorders and a decrease in sleep quality. 
If you, your children, or grandchildren use LED devices at night, we recommend minimizing exposure to blue light from these devices and reducing the harm done to sleeping cycles. If the exposure to artificial blue light cannot be reduced, then we recommend wearing blue light filtering glasses with melanin/ocular lens pigment (MOLP, OLP®) lenses.
The indoor nighttime lens may be more yellow in color but do not let that deceive you into thinking all lenses that are yellow can protect you. The yellow in these lenses actually contains a patented combination of melanin and ocular lens pigment, which decreases exposure to blue light. By decreasing exposure to blue light, this specially-designed lens prevents melatonin suppression and allows for proper sleep initiation and propagation, Other technologies, like orange-tinted lenses, lack this protection and, as a result, do not adequately decrease blue light exposure. Please do not be fooled, you need Melanin/OLP to effectively block blue light.
We will discuss in future newsletters how the technologies differ. For now, please share this newsletter with anyone that may watch TV, use electronic devices at night, or might be experiencing sleep disorders, diabetes, or weight gain. This information is also available on our website- www.tolentinoeye.org.
Tolentino Eye Research Foundation
Associate Professor of Ophthalmology, University of Central Florida
Director of Research, Center of Retina and Macular Disease
Tolentino Eye Research Foundation
Associate Professor, Harvard Medical School (Retired)
Co-Founder, Asian Eye Institute
 Kenney EL1, Gortmaker SL United States Adolescents’ Television, Computer, Videogame, Smartphone, and Tablet Use: Associations with Sugary Drinks, Sleep, Physical Activity, and Obesity. J Pediatr. 2016 Dec 9. pii: S0022-3476(16)31243-4. doi: 10.1016/j.jpeds.2016.11.015