articles: blue light special (light part 2)

In my previous post, I explained how Humans perceive color: in the eye’s retina, red cones are sensitive to longer wavelengths and blue cones are sensitive to shorter wavelengths. With so much buzz about red and blue light in everything from consumer products to medical treatments, further detail is necessary to understand these along with their applications/ implications.

In addition to rods and cones, retinal ganglion cells (intrinsically photosensitive neurons located near the inner surface of the retina that receive visual information) express photopigment, melanopsin. A study found that photoreceptors for these three (rods, cones and melanopsin) play different roles in regulating the pupil; too much or too little exposure to light can permanently alter the eye’s ability to regulate how much is allowed to enter. This confirms the plethora of anecdotal evidence for permanent eye damage from reading by candlelight, working in a mine, or being held captive in a dark space.

Conversely, too much light is problematic. Note that 1/3 of all visible light is high-energy visible (HEV). It’s commonly known that the sun has UV rays but recall how its white light and since white is all colors together, obviously that would include blue light. Some is beneficial. In moderation, it can boost alertness and mood, increase cognitive function and treat SAD.
It’s important to keep in mind that increasing man-made sources of HEV light (including– but not limited to– light bulbs and electronic screens) fool our eyes into sending the same signals to our brains as they would if were exposed to the sun. See the problem? Besides the potential for macular degeneration, eye strain can contribute to headaches.

Moreoever, HEV light scatters more easily than other visible rays– they’re dispersed as they strike air and water molecules in the atmosphere. Moreover, the anterior of the eye (its cornea and lens) do an impressive job filtering out UV light. In fact, less than 1% of UV from the sun reaches the retina. It’s ironic that we can be hypervigilant about wearing sunglasses that block 100% of UV light, yet simultaneously careless by relentlessly exposing ourselves to artificial blue light.

The body’s ability to produce circadian rhythms (see my previous post on this) depends upon consistent cycles of light and darkness. As the brain responds to stimuli, it produces hormones and chemicals accordingly. A study found that melanopsin is the primary driver for Melatonin production, i.e. light modulation is the main factor that influences the brain’s production of the hormone that makes you drowsy.

In light of all this, it becomes questionable to play around with our body’s master clock via artificial means without first making adjusting our schedule in order to regulate our exposure to light. Simulating natural cycles of light and darkness is the first step towards better sleep, among other benefits of removing the many sources of artificial interference with our circadian rhythms.

Between the tendency for overstimulation due to my ongoing struggle with anxiety and Fibromyalgia and the potential for eye strain resulting from countless hours spent on the computer (mainly doing research, which I share on this blog), I’ve found that blue-light blocking glasses significantly reduce the symptoms of overexposure to blue light. Fortunately, many manufacturers offer glasses (obviously in a variety of styles) that can include varying degrees of magnification for those who need it.


Scientific American: why it takes so long for vision to adjust from sunlight to a dark room

light as a central modulator of circadian rhythms, sleep and affect

circadian photoperception: aging and the eye’s important role in systemic health

melanopsin and inner retinal photoperception

distinct contributions of rod, cone & melanopsin photoreceptors to encoding irradiance

violet and blue light blocking intraocular lenses: photoprotection vs. photoreception

Psychiatry: Seasonal Affective Disorder

Genetics Home Reference: seasonal affective disorder

Seasonal Affective Disorder: an overview of assessment & treatment approaches

how light turns ordinary Hydrogen Peroxide into a MRSA treatment (without antibiotics)

light therapy for neonatal jaundice

endogenous porphyrin production in bacteria aminolaevulinic acid & subsequent bacterial photoeradication

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