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How does the color blue affect vision?

How does the color blue affect vision?

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Is the color blue harmful or beneficial for us? Do blue objects project similar effects on our vision as blue light does? How exactly does seeing blue affect human vision?

Blue is the fastest transmitted color in the spectrum. It is also the most easily refracted by the human eye. Blue light is omnipresent around us as it occurs both naturally and artificially.

In natural surroundings, we see blue light when the sun’s rays get transmitted through the earth’s atmosphere. Blue light rays are more easily scattered when they come in contact with air molecules. This occurs because blue color has the shortest wavelength of all colors in the spectrum. This is also the reason blue color reaches our eyes before any other color.

The sky also appears blue due to its rapid transmission and short wavelength.

Effects of Blue on the Human Body

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Natural blue light from the sun is used by our bodies to regulate our sleeping and waking cycle. This cycle is also known as the circadian rhythm. Exposure to blue light in the morning results in the release of cortisol in the human body. Cortisol is a hormone that is responsible for stimulating and waking us. It also stops the release of melatonin, a hormone that is responsible for inducing sleep.

At dusk, when the amount of blue light reduces with the setting of the sun, our cortisol levels lower. Melatonin starts being secreted and we start feeling sleepy.

This direct effect of blue light on our biological cycles shows how selectively sensitive our body is to the color blue. There is a clear connection between short wavelength colors and our physiological mechanisms of heart rate, sleep schedule, mood and alertness.

Exposure to blue objects and light considerably reduces stress levels. It also reduces heart rate and has a calming effect. It has been proven that blue light can even prevent people from taking extreme decisions. Installing blue lights in suicide-prone areas was found to reduce suicide rates. Suicides fell by more than 70 percent at Japan’s Yamanote railway line.

Similarly, in corporate or creative fields, people were found to be more productive in rooms with blue objects or surroundings. However, the sharp refraction causes visual fog if blue color is used extensively in interiors. A consensus by the University of Texas found that people were more productive in blue painted rooms than any other colored rooms. This could be because visual perception of blue color stimulates the mind and senses. It also was found to promote creativity and productivity. Based on this observation, it is advisable to paint offices and work spaces in blue color to ensure that people are at their creative best.

Viewing blue objects or color has both a calming and a stimulating effect on the mind, leading to increased production levels. In this manner, visual perception of blue directly effects the human psyche.

The absence of sunlight in geographically polar areas results in over-secretion of melatonin and under-secretion of cortisol. This occurs due to the prolonged absence of blue light, which is the prime requirement for cortisol secretion. People living in such areas suffer from depression and drowsiness. Depression resulting from lack of daylight is called Seasonal Affective Disorder (SAD). Blue light acts as an antidepressant and is therapeutic in such cases.

Side-effects of Blue Color on Visual Perception

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In some cultures, the color blue has a negative perception. The sentences ‘’feeling blue” or “beaten black and blue” symbolize sadness, depression and pain. It is a cold color. It is often associated with coldness, unresponsiveness and emotional detachment.

The term “blue-blooded” is associated with aristocracy. It is an old belief that people of noble birth did not work outdoors in the sun. As a result, they had pale skin. Blue blood vessels showed underneath it. This resulted in the common analogy that people with blue blood vessels are of noble birth.

Overuse of blue color becomes oppressive to the eyesight. When our lens perceives blue objects or color, they become flat and try to push the image due to sharp refraction. This is why people perceive blue colored spaces to be smaller and diminishing.

Blue colored food items have a history of being poisonous. There are rarely any edible blue objects. So blue is considered to be a very unappetizing color. Due to this, often blue is used as a hunger suppressor.

Some diet plans also recommend serving food on blue plates. It reduces appetite considerably.

Even dyeing the food blue is an effective remedy to suppress appetite. Seeing blue objects on the plate triggers the hypothalamus. It warns the mind against any potential danger about the food item.

Natural blue light is important for our biological clocks. But it also has a negative side. Over-exposure to blue light can be harmful for the vision.

The wavelength of blue light ranges between 415 nm – 455 nm. It is a high energy light and can result in eye damage. Due to the short wavelength of blue light, the focus is formed in front of the retina and not in the center of it. Thus, long exposure to blue light inevitably results in worsening of eye fatigue and myopia.

The cornea and the lens of the human eye are very efficient in obstructing ultraviolet rays. In fact, 99.9% ultraviolet radiation gets blocked from reaching the retina even without sunglasses. The light-sensitive retina is effectively shielded from the ultraviolet rays. On the other hand, all visible blue light passes through the cornea and the lens unaffected.

A recent research from the University of Toledo reveals what happens when retinal collides with the blue light particles. This leads to chain reactions that are potentially hazardous to the retinal cells. It is contradictory that to observe blue light, we definitely need retinal. Prolonged exposure to blue light contributes to macular degeneration due to aging, which is a leading cause of blindness.

Because blue light scatters better than other visible light, it is not as easily focused. This becomes a serious disadvantage when using digital devices for a long period. When we look at computer screens and other gadgets for a long time, we encounter a large amount of blue light. This blue light is unfocused, reduces contrast and contributes to eye strain. Researches show that lenses that can obstruct blue light with wavelengths less than 450 nm improve contrast substantially. This is why specially designed computer glasses with yellow lenses increase comfort when using computers for a long time.

Vision Problems due to Blue Color

Chromostereopsis is an optical illusion in which depth is expressed in the form of two-dimensional color images, of combinations like blue-red, green-red, red-gray or gray-blue. There have been reports of such illusions for over a century. They are now perceived as some form of chromatic aberration.

A difference of about 2 Diopters is encountered in optical power of the colors (Blue : -1.5, Red: +0.5). This effect aggravates when the images are viewed using glasses for treating myopia. On removal of these glasses, the effect seems to disappear almost completely.

Cyanopsia is a medical condition in which a person might see everything tinted blue. It is also called blue vision. It generally occurs for periods ranging from a few days to a few months after removal of cataract from the eye. It does not indicate a disease if it is not accompanied by another medical symptom.

The eye’s lens has a yellow tint which reduces the intensity of blue light reaching the retina. When the lens is removed due to cataract, it is replaced by a clear artificial lens. The artificial lens allows more blue light than usual to fall on the retina. This leads to the eyes seeing blue objects everywhere.

The scattering of light by particles in a colloid or an extremely fine suspension is known as Tyndall Effect or Tyndall Scattering. An example of Tyndall Effect is the observance of blue color in the smoke emitted by motorbikes (more specifically, two-stroke machines). In this effect, longer wavelengths get transmitted more while shorter wavelengths get scattered.

Blue : A boon and bane

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The imminent significance of blue light in regulating our circadian rhythm is obvious. However, too much exposure to blue light disrupts this rhythm. The modern day routine of human beings involves working late hours on glaring screens. Even leisure hours are spent watching mobile screens. These are sources of artificial blue light. Exposure to gadgets with screens before sleep hours disrupts the secretion of melatonin and promotes cortisol levels. This results in wakefulness and disturbed sleep routine. Sleep loss has become a major problem faced by many young people and children as a consequence of over exposure to blue light.

Blue objects calm the mind but are also detrimental to vision. They lower depression as well as increase myopia. On one hand they prevent suicides and on the other they make us productive. The towering benefits of blue objects towards the mind are indispensable while their harmful effects on vision can’t be ignored.

Whether we let blue thicken our glasses or act as a stress buster is really our call!

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