Blue Light & Eyes

Most people are aware that ultraviolet light damages the eyes, but did you know that so does most of the visible blue and violet light? For that reason we have protecting yellow pigments in the retina: lutein and zeaxanthin. These pigments absorb the blue and violet, including ultraviolet, so this harmful light does not reach the underlying tissue of the retina.

In the eyes, blue, violet and ultraviolet light trigger oxidation in the retina, and that leads to so-called age-related macular degeneration, or AMD. The light-sensitive cells of the retina lose in function and finally stop working completely. This is a common source of bad eyesight and blindness.

There is a protection system, the yellow pigments of "macula lutea", the yellow spot in the retina. These pigments have the ability to absorb blue light so it never harms the cells. The yellow pigments are consumed on a regular basis and must be replenished through diet. The more pigments you have in your yellow spot, the better protection you have. The protecting pigments are lutein and zeaxanthin, two carotenoids which are present in many foodstuffs.

Melanin, the pigment that gives brown eyes their colour, also protects the eye. (Don't confuse the pigment melanin, with the hormone melatonin, they are two entirely different things.) If you have blue eyes, a hundred times as much light reaches the back of your eye, compared to someone with dark brown or black eyes. So AMD is more threatening to blue-eyed people than to those with darker eye pigment. But while you cannot affect your inherited eye colour, the amount of yellow pigment in the yellow spot is determined by the amount of lutein and zeaxanthin in your diet.

To sum it up: In order to protect the retina and full vision, the wise course is to combat the problem from two sides. One being to reduce exposure to harmful forms of light, the other being to provide the body with sufficient amounts of dietary lutein and zeaxanthin, yellow pigments that absorb blue light reaching the retina.

Although blue and violet light might harm the eyes, we need some of it. One reason is the melatonin system. As a matter of fact, too little of this light might cause sleep disorder.

Blue Light & Sleep Disorder

In 1958 melatonin, a hormone produced by the pineal gland, was isolated. It is manufactured from serotonin by an enzyme which is inhibited by light. (Interestingly, another area producing melatonin is the retina of the eyes!) This hormone has proved to regulate sleep, affect the hormonal balance, dreams, sexuality, immunity, and much more.

Light enters through the eyes, stimulates the retina, signals are then transferred through the optic tract (a bundle of nerve fibres) to the hypothalamus (another gland), and then further to the pineal gland.

Light decreases the production of melatonin, darkness increases it. More melatonin lets us sleep better, too little melatonin causes insomnia.

Melatonin controls our sleep and the presence or absence of light controls the production of melatonin. Conclusively, our exposure to light is connected to our sleeping pattern, to our circadian rhythm. Slightly simplified we can say that light keeps us awake, darkness makes us sleep.

LIGHT -> LESS MELATONIN -> AWAKE

DARKNESS -> MORE MELATONIN -> ASLEEP

Our ancestors lived by this rhythm, but how is it today when we can be surrounded by light 24 hours a day? Are we overexposed to light, to an extent that harms our health?

As a matter of fact, when people sat by the fire in the evenings, nothing changed, because the light fire creates doesn't influence the pineal gland.

Not even gas lamps or bulbs of the old type do. The reason is that they emit yellow light, and the pineal gland, which has been evolving in interaction with daylight, reacts only to blue light. In that respect, yellow light is equivalent to darkness.

Modern low-energy lamps, however, fluorescent lights, LED light, computer, television, and mobile phone screens, all of them emit blue light. During the last decades, our exposure to blue light has grown exponentially! During the same period of time, we have seen sleeping disorders increasing to a degree which today makes a well-sleeping individual a rarity. The general level of melatonin remains too low all the time.

The consequences of chronic sleep disorder can hardly be overrated. Gradually, health degenerates on all fronts, physically, mentally, emotionally. All healing and regeneration occurs during sound sleep. Lacking that natural stage of regular reparation, the whole organism breaks down.

Melatonin has more functions than sleep regulation, and of course they are deteriorating as well when the melatonin level is consistently too low. One interesting detail is its effect on cancer.

Blue Light & Cancer

Melatonin inhibits the growth of several forms of cancer cells. This is so pronounced that blindness reduces the occurrence of cancer. While this has been insufficiently studied on humans, studies of animals leave no room for doubt; blind animals have less cancer. No light enters the system; their melatonin level is permanently high. (Supplementary treatment with melatonin is beneficial in many cases of cancer.)

Blue light keeps the melatonin production too low, and melatonin deficiency is linked to an increased occurrence of cancer. Although that has not been explicitly studied, there is good reason to suspect that overexposure to blue light contributes to the development of cancer!

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