Blue Light Can Help Reset Sleep Cycle

Scientists Show Blue Light Can Help Reset Sleep Cycle
February 1, 2006

Teenagers' morning drowsiness is often caused by out-of-tune body clocks, in a condition known as "delayed sleep phase syndrome." Scientists now say that timing exposure to blue light -- avoiding it during the first two hours of being wake, then getting a good dose of it -- can help restore the sleep cycle, so teens feel sleepy earlier at night and are more awake in the morning.

BACKGROUND: Researchers at Rensselaer Polytechnic Institute are studying how light -- especially blue light -- affects our body's daily rhythms. By getting enough blue light at the right time and blocking it out at others, it is possible to correct distorted sleep patters for the elderly (who tend to wake up too early), teenagers (whose internal clock is usually set for late nights and sleep-in mornings), and shift workers.

HOW BODY RYHTHMS WORK: Circadian rhythms are biological cycles in the body that repeat approximately every 24 hours, including the sleep/wake cycle, along with body temperature, hormone levels, heart rate, blood pressure, and pain threshold. The brain has its own internal "pacemaker" that determines when nerve cells fire to set the body's rhythms, although scientists can't precisely explain how it does so.

The colors of the light spectrum can affect the body's rhythm differently, particularly when it comes to sleep patterns. For instance, daylight is dominated by short, visible wavelengths of light that provides a blue visual sensation, like the blue sky. But l how bright the light is, how far away, how long you're exposed and when you're exposed to light also have to be considered. Also, we are more likely to sleep soundly in the wee hours of the morning, when our body temperature is lowest, and most likely to awaken when our body temperature starts to rise, usually between 6 AM and 8 AM. As we age, the brain's "pacemaker" loses cells, changing circadian rhythms, especially sleep patterns. The elderly may nap more frequently, have disrupted sleep, or awaken earlier.

RESETTING THE CLOCK: The RPI researchers developed a method for resetting the internal "master clock" in studies of both teens and the elderly. The scheme removes blue light at certain times (depending on how one wants to "reset the clock") by wearing orange glasses, followed by exposure to blue light and darkness at nighttime. The key is a distinct, repeated pattern of light and dark.
SLEEP STAGES: Stage 1: drowsiness. Stage 2: light sleep. Stages 3 and 4: deep sleep. Stage 5: Rapid-eye movement (REM) sleep. REM is when people dream, perhaps because the brain is more active and the muscles are relaxed. These five stages occur cyclically; a person may complete five cycles in a typical night's sleep.

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Caffeine Free: Blue Light Makes People Alert at Night
By LiveScience Staff

There's much more than meets the eye to how we perceive light, researchers have learned in recent years. The latest revelation: blue light helps fend off drowsiness in the middle of the night.

A small study of 16 volunteers found that exposure to short-wavelength light, or blue light, perked them up immediately.

"Light exposure to this system, particularly blue light, directly reduces sleepiness," said Steven Lockley of the Brigham and Women's Hospital. "Subjects exposed to blue light were able to sustain a high level of alertness during the night when people usually feel most sleepy, and these results suggest that light may be a powerful countermeasure for the negative effects of fatigue for people who work at night."

The study, sponsored by National Space Biomedical Research Institute, is detailed in the Feb. 1 issue of the journal Sleep.

"The effects lasted as long as the blue light was on, which was 6.5 hours," Lockley told LiveScience. "I expect it would last at least for a few hours more if we extended the light exposure for longer although not ad infinitum. We hope to do studies with longer exposures shortly."

The work adds to other evidence that the human eye sees things we're not consciously aware of. Other research has shown that the eye's hidden perceptive abilities help control our 24-hour internal clock, so we know when to sleep and when to wake.

"These findings add to the body of evidence that illustrates that there is a novel photoreceptor system that exists in the human eye in addition to that used for sight," Lockley said.

Eventually the finding could lead to ways to improve alertness in nighttime drivers, shift workers, pilots or astronauts, said Lockley, who is also an Assistant Professor at Harvard Medical School. More work needs to be done, however. Blue light in the wrong doses can be dangerous to the eye.

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When light has you singing the blues:
Blue light resets body rhythms for sounder sleep, higher alertness
By William J. Cromie
Harvard News Office

Blue light outshone white in a Harvard University experiment to find better ways to reset our body clocks.

Jet-setters and shift workers now sit in front of glaring white lights to readjust their body rhythms and avoid sleep and alertness problems. These new experiments suggest that they would be better off mugging for blue lights.

The research also contradicts what many scientists believed for years, that the 24-hour biological clock is set by sight alone. Until 1995, dogma held that the intensity of light striking receptors that give humans color vision also adjust the daily cycle that controls sleep, performance, and other physical and behavioral factors. Now, there is conclusive evidence for a second system that dominates the setting of daily rhythms in creatures from bacteria to international travelers, even blind ones.

"The visual system in humans is most sensitive to green light," notes Steven Lockley of Brigham and Women's Hospital, a Harvard research and teaching affiliate. "But when we exposed 12 healthy young men and women to the same amount of either green or blue light, their 24-hour rhythms shifted twice as much with blue than with green."

After 6.5 hours of exposure, blue light readjusted their body clock by 3 hours, green light by about 1.5 hours. If you normally feel your eyelids getting heavy at 11 p.m., a 6.5-hour dose of blue light might keep you alert until 2 a.m. If a change in shift leaves you sleepless at 4 a.m., blue light might help you sleep three hours longer. (Which way the shift goes depends on when the light exposure takes place.)

To explain the research findings, there has to be one system that controls color vision, providing a greater acuity for green than for other colors, or wavelengths, of light. A separate system must involve a 24-hour pacemaker that keeps your body linked to the daily ups and downs of the sun.

"Both systems might be involved in setting circadian (24-hour) rhythms, but we think that the one that responds to blue light is the dominant one," says Charles Czeisler, a professor of medicine at Harvard Medical School, in whose laboratory the research takes place. "The wider-ranging implication of our work is the demonstration that the standard of illumination used by the lighting industry and clinical research community is inappropriate when assessing its effects on the circadian system."

"Those implications," adds Lockley, "extend to the design of light systems to treat circadian sleep disorders such as those tied to shift work, jet lag, and long-duration space travel. They also bear on changes in light exposure associated with aging and blindness, as well as ensuring proper alignment of internal rhythms with the outside world, particularly important in the current 24/7 society."

The blind lead the sighted

The obvious way to prove that separate systems govern color vision and body rhythms is to test blind people. Czeisler was trying to puzzle out why some blind people easily adjust to the 24-hour cycle while others toss and turn through a lifetime of sleeping problems, when he found the proof.

In 1990, he interviewed a blind man who claimed to experience no trouble sleeping. "I thought to myself that he is either not totally blind or he's not aware that his sleep is disturbed," Czeisler recalled. "Some blind people are not aware that their sleeping patterns differ from those of sighted people. Eventually he convinced me he had no trouble sleeping."

Moreover, his light blue eyes were "crystal clear and healthy looking. That led me to wonder whether his blind eyes might still be able to convey photic (light) information to the circadian clock."

Czeisler then checked to see if exposure to light would suppress a hormone known as melatonin. During night hours, melatonin peaks, decreasing alertness and increasing sleepiness. Daylight clears away the veil as melatonin levels decrease. That's what happened in his blind subject.

If the man couldn't see, something else must be keeping his body clock running smoothly. "It was a 'eureka moment' for me," Czeisler remembers. "It changed my worldview of how light resets the human clock."

But it didn't change the world's view. Czeisler reported his discovery but no scientific journals would publish his work. Other researchers did similar experiments on blind rats and mice, and they got the same results. The evidence became too overwhelming to ignore, and the discovery that human eyes have two functions was finally published in the New England Journal of Medicine in 1995.

Setting the blues

The recent experiments with blue light, published in the Journal of Clinical Endocrinology and Metabolism this month, add further proof that eyes both see and adjust internal body rhythms.

How do the clock adjustments take place? A specialized subset of light-sensitive cells, which apparently have nothing to do with vision, exists in the retina, or back of the eye. These cells boast extensions that reach deep into the brain to the hypothalamus, the location of the body's internal clock. They contain melanopsin, a recently discovered substance that may sense light and transmit signals that change the clock settings.

"That's a theory," Czeisler cautions, "not a done deal. The melanopsin cells may operate alone or it may get input from the classical vision system. In any case, melanopsin seems to dominate."

"About 20 percent of totally blind people have their biological clocks synchronized by light even though they cannot see it," Lockley points out. "Of the other 80 percent, more than half suffer serious sleeping problems that result from a failure to reset the clock."

Blind or not, why does blue light set the clock more effectively than green or red light? The short answer is that no one knows. "But it's probably not an accident that looking up at the blue sky has twice the resetting effect on our circadian clocks as looking down at green grass," Czeisler notes.

One theory holds that the birth of life on Earth occurred in the ocean, and that origin established an evolutionary preference. The idea is backed up by evidence that some of the earliest creatures to evolve, one-celled algae, react preferably to blue light.

Lockley, Czeisler, and George Brainard, a researcher from Thomas Jefferson University in Philadelphia who collaborated on the experiments, readily admit there are a lot of loose ends to tie up before the mysteries of internal pacemakers are solved. One thing they want to do next is to determine how much easier it would be to use blue light for resetting the alertness of jet travelers, shift workers, students, astronauts, and the military. Czeisler imagines a widely available blue-light system in homes that would adjust your body clock continuously to your schedule.

"Our study opens the door to both understanding how humans and other organisms adjust to the planet's rhythms, and how we can practically align our internal time to the demands of a 24/7 society."

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Mother’s Glasses that Block Blue Light Provide Sleep Hormones for Babies

Melatonin, the sleep hormone, appears in breast milk in proportion to the amount in the mother’s blood. Exposing the eyes to the blue component in light suppresses melatonin. A typical mother may only be in darkness a few hours and make very little melatonin. Wearing glasses that block the blue light or using blue-blocking light bulbs may allow her to make more melatonin that will help both the baby and her sleep better.

University Heights, OH (PRWEB) February 20, 2006 -- It has been known for a number of years that melatonin, the sleep hormone produced in the pineal gland appears in breast milk. The amount varies throughout the day and night in keeping with the amount of melatonin the mother has in her blood. It has also been known for many years that the pineal gland only produces melatonin when the individual is in darkness. Before the arrival of electric lights we were in darkness 12 hours a day, on average. Now most of us are lucky to be in darkness for 7 or 8 hours a day. For a new mother this may drop to 4 or 5 hours a day. This means the time when her milk contains melatonin may be very short. Fortunately there is a way out of this problem that may make both the babies and their mothers and fathers sleep much better.

In 2001 two independent studies found that not all colors of light have the same effect in suppressing melatonin. It was found that it is the blue component in light that has the biggest effect. In a study at the University of Toronto it was found that if subjects wore goggles that blocked the blue light, they continued making melatonin despite being exposed to bright light. In blocking the blue light we still have the yellow, orange and red light to find our way around, watch television, read or whatever we want to do. Physicists at John Carroll University have developed glasses and light bulbs with filters that block blue light. They make them available at _www.sleeplamps.com.

This means that a nursing mother may provide milk for her infant that is rich in melatonin which may help the child sleep better. Having more melatonin will also help the mother sleep better. This can be accomplished if the mother simply puts on glasses that block the blue light for part of the day and night. Combined time in real darkness and wearing the glasses need not excel 12 hours. Wearing them longer will not produce more melatonin. Most important is avoiding exposure to white light during the night when getting up for feeding the baby. Nightlights or regular lights that block blue light should be used or else the glasses should be worn. Even a few minutes exposure to white light will wipe out melatonin production, possibly for the rest of the night. Putting on glasses a few hours before bedtime seems to be the most practical thing and wearing them for shorter time in the early morning, if awake, to extend the nighttime.

Glasses that fit tightly and block light coming in form the side and light bulbs that do not cause melatonin suppression are available on the web at _www.sleeplamps.com

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Abstract

Background:
Complete blindness generally results in the loss of synchronization of circadian rhythms to the 24-hour day and in recurrent insomnia. However, some blind patients maintain circadian entrainment. We undertook this study to determine whether some blind patients' eyes convey sufficient photic information to entrain the hypothalamic circadian pacemaker and suppress melatonin secretion, despite an apparently complete loss of visual function.

Methods:
We evaluated the input of light to the circadian pacemaker by testing the ability of bright light to decrease plasma melatonin concentrations in 11 blind patients with no conscious perception of light and in 6 normal subjects. We also evaluated circadian entrainment over time in the blind patients.

Results:
Plasma melatonin concentrations decreased during exposure to bright light in three sightless patients by an average (±SD) of 69±21 percent and in the normal subjects by an average of 66±15 percent. When two of these blind patients were tested with their eyes covered during exposure to light, plasma melatonin did not decrease. The three blind patients reported no difficulty sleeping and maintained apparent circadian entrainment to the 24-hour day. Plasma melatonin concentrations did not decrease during exposure to bright light in seven of the remaining blind patients; in the eighth, plasma melatonin was undetectable. These eight patients reported a history of insomnia, and in four the circadian temperature rhythm was not entrained to the 24-hour day.

Conclusions:
The visual subsystem that mediates the light-induced suppression of melatonin secretion remains functionally intact in some sightless patients. The absence of photic input to the circadian system thus constitutes a distinct form of blindness, associated with periodic insomnia, that afflicts most but not all patients with no conscious perception of light.

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The Blue Light Hazard

Sight requires light. As years go by, accumulation of lipofuscin (cellular debris) in the retinal pigment epithelium (RPE) may make the retina more sensitive to damage from chronic light exposure.6-15 Retinal light damage has been studied by exposing experimental animals and cell cultures to brilliant light exposures for minutes to hours. According to some of these studies,16-19 blue light waves may be especially toxic to those who are prone to macular problems due to genetics, nutrition, environment, health habits, and aging. On the other hand, acute retinal phototoxicity experiments such as these can cause retinal injuries, but they cannot simulate a lifetime of normal light exposure. Some researchers have noted strong similarities between photic injury and retinal abnormalities caused by years of overexposure to light.47-50 Others have found no similarities. 51-58 Whereas the shorter wavelengths of UV-A and UV-B are somewhat filtered by the lens and cornea, animal studies have shown that the light spectrum from UV through blue can be harmful. During lengthy exposures of up to 12 hours, toxicity of the retina is known to increase as the light wavelengths grow shorter.20-33 56 More recently, research on human fetal cell tissue has also revealed damage from blue light exposure.78 Fortunately, healthy retinas have a wide array of built-in chemical defenses against UV-blue light damage. They bear such imposing names as xanthophyll, melanin, superoxide dismutase, catalase, and glutathione peroxidase. And then there are the more familiar agents vitamin E, vitamin C, lutein, and zeaxanthin. 35-39 Unfortunately, these defenses can weaken with disease, injury, neglect, and age.

Another built-in protective process is that the natural lens takes on a yellowish tint with age, which helps to filter blue light.59 60 After cataract surgery, however, patients lose that benefit. Some doctors now recommend replacing the damaged lens with an intraocular lens (IOL) that is tinted to block blue light.79 The patient should be made aware, however, that this procedure will diminish scotopic (night) vision.61 62

According to the CVRL Color & Vision database,63 light waves measuring approximately 470nm to 400nm in length are seen as the color blue. The blue bands of the visible light spectrum are adjacent to the invisible band of ultraviolet (UV) light. UV is located on the short wave, high frequency end of the visible light spectrum, just out of sight past the color violet. It is divided into three wavelengths called UV-A , UV-B, and UV-C. The effects of UV-C (100nm-290nm) are negligible, as the waves are so short they are filtered by the atmosphere before reaching the eyes. UV-A (320nm-400nm) and UV-B (290nm-320nm) are responsible for damaging material, skin, and eyes, with UV-B getting most of the blame.

When light hits a photoreceptor, the cell bleaches and becomes useless until it has recovered through a metabolic process called the “visual cycle.” 30 31 Absorption of blue light, however, has been shown to cause a reversal of the process in rodent models. The cell becomes unbleached and responsive again to light before it is ready. This greatly increases the potential for oxidative damage, which leads to a buildup of lipofuscin in the retinal pigment epithelium (RPE) layer 64 (see Fig. 3). Drusen are then formed from excessive amounts of lipofuscin, hindering the RPE in its ability to provide nutrients to the photoreceptors, which then wither and die. In addition, if the lipofuscin absorbs blue light in high quantities, it becomes phototoxic, which can lead to oxidative damage to the RPE and further cell death (apoptosis).65

Blue light is an important element in "natural" lighting, and it may also contribute to psychological health.71 72 Research, however, shows that high illumination levels of blue light can be toxic to cellular structures, test animals, and human fetal retinas.56 66-70 78-81 (Also see "Random Quotes" below.) The industry has established standards for protecting consumers from extremely bright light and from UV radiation; but no standards address the blue light hazard that may be affecting millions who have retinal problems. Blue light is a duplicitous character who needs to be carefully watched. Until research proves him to be either a friend or a foe, education will help consumers make decisions based upon the facts.

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Random Quotes
Cautionary Statements From The Literature​

" ...people with the highest levels of exposure [to UV-A, UV-B, and blue light] in the middle of the day had two fold increased risks of AMD. Our results showing the increased risk from high exposures to solar radiation underline the importance of ocular protection in European populations." Augood, C. et al. Age-related maculopathy and macular degeneration in elderly European populations: the EUREYE study, 2004.

"The photoreceptors in the retina . . . are susceptible to damage by light, particularly blue light. The damage can lead to cell death and diseases." Shaban H, Richter C. A2E and blue light in the retina: the paradigm of age-related macular degeneration. Biol Chem 2002 Mar-Apr;383(3-4):537-45.

"The effectiveness of light in inducing photodamage to the retina increases with decreasing wavelength from 500 to 400 nm." Andley UP,? L.T. Chylack Jr LT. Recent Studies on Photodamage to the Eye with Special Reference to Clinical and Therapeutic Procedures. Photodermatology Photoimmunology and Photomedicine 1990; 7:98-105.

". . . when albino rats were exposed to either monochromatic blue light of 403 nm . . . or monochromatic green light of 550 nm . . . massive apoptotic cell death occurred after illumination with blue light." Remé et al. Apoptosis in the Retina: The Silent Death of Vision C E. News Physiol Sci 15: 120-124, 2000.

". . . continuous exposure to blue light is potentially dangerous to vision." Koide R, Ueda TN, Dawson WW, Hope GM, Ellis A, Somuelson D, Ueda T, Iwabuchi S, Fukuda S, Matsuishi M, Yasuhara H, Ozawa T, Armstrong D. Nippon. Retinal hazard from blue light emitting diode. Ganka Gakkai Zasshi. 2001 Oct;105(10):687-95.

". . . high levels of exposure to blue or visible light may cause ocular damage, especially later in life, and may be related to the development of age-related macular degeneration." Taylor HR, West S, Munoz B, Rosenthal FS, Bressler SB, and Bressler NM. The Long Term Effects of Visible Light on the Eye. Archives of Ophthalmology 1992; 110:99-104.

"I think chronic blue light is probably damaging." Joshua Dunaief, MD, in Bethke W. Should We Block The Blue. Review of Ophthalmology Oct 15 2003; 10(10).

"Increased risk of AMD may result from low levels of lutein and zeaxanthin (macular pigment) in the diet, serum or retina, and excessive exposure to blue light." Bone RA, Landrum JT, Guerra LH, Ruiz CA. Lutein and Zeaxanthin Dietary Supplements Raise Macular Pigment Density and Serum Concentrations of these Carotenoids in Humans. Journal of Nutrition 2003 Apr;133(4):992-8.

"The high-energy segment of the visible region (400-500 nm) is enormously more hazardous than the low energy portion (from 500-700 nm)." Young RW. Solar Radiation and Age Related Macular Degeneration. Survey of Ophthalmology 1988; 32(4): 252-269.

"Visible light of short wavelength (blue light) may cause a photochemical injury to the retina, called photoretinitis or blue-light hazard." Okuno T, Saito H, Ojima Evaluation of blue-light hazards from various light sources. J. Dev Ophthalmol. 2002;35:104-12.

"[The] Action spectrum for blue-light induced [retinal] damage shows a maximum at 400 nm and 450 nm." Bartlett H, Eperjesi F. A randomised controlled trial investigating the effect of nutritional supplementation on visual function in normal, and age-related macular disease affected eyes: design and methodology. Nutrition Journal 2003, 2:12.

"Because sunlight and many high-intensity artificial light sources contain relatively high proportions of blue, and the retina as well as pigment epithelium contain several types of blue-absorbing molecules, the short-wavelength band of the visible spectrum may contribute to the pathogenesis of age-related macular degeneration and amplify some forms of inherited retinal degeneration." Remé CE, Wenzel A, Grimm G, Iseli HP. Mechanisms of Blue Light-Induced Retinal Degeneration and the Potential Relevance for Age-Related Macular Degeneration and Inherited Retinal Diseases SLTBR Annual Meetings Abstracts 2003.

". . . the photon catch capacity of the retina is significantly augmented during blue-light illumination, which may explain the greater susceptibility of the retina to blue light than to green light. However, blue light can also affect function of several blue-light-absorbing enzymes that may lead to the induction of retinal damage." Grimm C, et al. Rhodopsin-Mediated Blue-Light Damage to the rat Retina: Effect of Photoreversal of Bleaching. Invest Ophthalmol Vis Sci 2001 Feb;42(2):497-505.

"It is not too harsh to state that virtually all persons with vision problems should be removed from a light environment where the predominant light waves are a temperature above 3500K or a wavelength less than approximately 500 nm." Elaine Kitchel, M.ED.VI. The effects of fluorescent light on the ocular health of persons with pre-existing eye pathologies. American Printing House for the Blind, 2000.

"Exposure to the eye to intense light, particularly blue light, can cause irreversible, oxygen-dependent damage to the retina. We have found that illumination of human retinal pigment epithelium cells induces significant uptake of oxygen that is both wavelength and age dependent...and contribute to the development of age-related maculopathy." Rozanowska M, et al. Blue light induced reactivity of retinal age pigment. Journal of Biological Chemistry 1995; 270(32):18825-18830.

". . . blue light induces apoptosis in human fetal RPE cells." E.M. Gasyna, K.A. Rezaei, W.F. Mieler, and K.A. Rezai. Blue light induces apoptosis in human fetal retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 2005 46: E-Abstract 248.

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German scientists have warned that the large proportion of blue light emitted by CFL’s can lead to a diminished production of the important hormone melatonin. This in turn can lead to a wide variety of diseases and conditions: sleeping disorders, cancer, cardiovascular disease, etc. (23). But the specific light emitted by CFL’s could also influence the production of other hormones and neurotransmitters.

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PARENTS have been warned to keep young children away from areas lit by new-style light-emitting diode (LED) lights and to avoid toys that use the lamps. Public health watchdog Anses has just completed first tests on the lights, which are starting to be increasingly used in many different applications, and says it found that some were not suitable for public use.

LED bulbs can last for 25 years and give out an intense blue-white light. They give the same illumination as a traditional incandescent lamp, but use only a tenth of the energy. They are starting to replace traditional lamps and a report in the Daily Mail said London’s Dorchester Hotel had cut its £150,000 lighting bill by a third since switching to LED lighting. Now they are used as car running lights, billboards, kitchens and on TVs. Anses tested nine types of LED lights against the IEC 62471 standards and rated three in the second-highest risk band.

It says the intense blue-white light is a “toxic stress” on the retina, with a severe dazzling risk. Youngsters are particularly sensitive to this risk as their eyes are still developing and the lens is not capable of filtering out the light wavelengths.

Anses that the intensity of LED lights should be reduced and public use restricted to lamps that give off the same intensity as traditional ones. High-intensity LED lamps should be for professional use only.

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Incandescent as well as halogen lamps offer a balanced, nearly natural light spectrum with the most complete spectral power distribution. CFLs only pluck two to four small single color bands out of the full light spectrum; this is a far cry from the harmony of natural light.
Don't have wool pulled over your eyes: in publications and discussions, industry representatives and politicians alike argue that the light quality of CFLs would be just as good as incandescent light. Wrong. Time and again, the color temperature is used as "proof". The color temperature, however, only characterizes one single aspect of light quality, namely the general light color.

An even more important aspect is the light spectrum, its spectral distribution as well as the balance and interactions of its individual colors, which form light as a whole. Just as the color white only comes into being when all wavelengths from violet and blue over green and yellow to orange and red come together in harmony and blend into each other. Just as a good orchestra with its many different instruments coalesces into one, thereby creating harmony and musical pleasure.
It is the light spectrum that is essentially responsible for the quality, health and balance of a light source, for its resemblance to natural daylight, for the important color rendering of our entire environment, for a sense of well-being.
Thus Thomas Mertes, a Philips plant manager, said in 'Spiegel- TV': "I would not recommend using energy-saving lamps for areas where colors need to be rendered accurately, for example, above the dining table. Otherwise, the food will not look too appetizing and the person sitting across such as a guest may appear rather gray. Actually, you may have the impression as if the food was not to his liking." Sabine Gedder, head of the Hamburg School of Painting, says in the NDR broadcast 'Markt': “It looks terrible. The color red turns into orange and the yellow looks almost green.”

In comparison with natural daylight and bulbs, the spectral distribution of CFL is worse, featuring unnaturally narrow color bands. CFLs contain only few colors with steep spikes, having hardly any spectral color output in-between them. Staying with the orchestra, this would be as if only two or three of the many musicians were to take center stage, playing loud and out of tune. And all the others were to keep silent.
"An artificial light source is the more harmful, the more strongly it deviates from the spectral characteristics of natural sunlight," health care professionals warn. All of this and more is swept under the rug, even by science journalists who should know better than that such as the TV host Ranga Yogeshwar in the ARD discussion panel "Hart aber Fair".

Both the unnatural light spectrum as well as the annoying flickering are not too inviting. Both occurs when a light source illuminates something close or farer away. In the outside darkness, I can still measure the light flicker many meters away from those homes illluminated by CFLs, including the flickering of TV and computer screens. Go for a walk along such homes in the dark and let the various lights wash over you: Here is a home that feels warm and inviting, owing its cheerful glow to incandescent light. And over there they have typical energy-saving lamps, fluorescent lamps or computer screens just like at a supermarket.

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Risks of modern light sources

Due to their high proportion of red in the near infrared and long-wave range, the “good old light bulbs” are easy-on-the-eye. In contrast to that the modern mercury light sources must be viewed much more critically.
Mercury light sources can be found in the backlight of TFT flatscreens (notebooks and computers) as well as in TFT television screens, energy saving lamps and fluorescent tubes. The biggest strain to the eye is caused by TFT screens in front of which people spend many hours daily during their working life. In addition to the radiation load coming from the screen the fluorescent lighting at the workplaces contributes to this negative effect.
Mercury light in TFT screens

Flat screens use mercury light as a backlight. This light is - as in the case of fluorescent tubes - produced by gas discharge. While the spectrum of the white daylight is composed of a harmonic proportion of colours, fluorescent lamps resp. TFT screens radiating mercury light have a discontinuous spectrum. The latter shows high unnatural short-wave proportions of blue (blue, indigo, violet) with pointed "energy highs". However the red area, which is responsible for promoting blood circulation, shows low energy (see graph).

Spectrum of the Daylight and the discharge lamp: (visit website to view the image)

A danger to the retina?

A person doing on-screen work looks directly into the source of light for a long time.This means that the radiation hits - unfiltered and bundled - the spot of the sharpest vision, the so-called macula lutea, also called the “yellow spot” which is located on the back wall of the eyeball. The lens filters ultraviolet light, blue light is not. This proportion of blue light can, in the long term, lead to damage such as age-related macular degeneration (AMD), an incurable disease of the yellow spot. Numerous scientific studies on AMD have proven that blue light can be harmful to the eye. Oxygen radicals damaging cell metabolism in the eye are produced under the influence of blue light.

Blue light impedes vision

Blue light breaks more easily than red light. It is focussed on different level in the eye than long-wave light, which results in chromatic aberrations and blurredness. This is why pilots and athletes often wear yellow glasses, which filter the proportion of blue light, thus heightening visual acuity and contrast perception. Often AMD patients also get prescriptions for yellow glasses or lenses in order to protect their macula from destructive blue light.
Graph - eye lens: (visit website to view the image)

Disorder of hormonal balance

Due to its high proportion of blue light mercury light also affects the hormonal balance in a negative way by reducing the production of melatonin and boosting the generation of the stress hormones cortisol and ACTH. Disorders of the hormonal balance can lead to illnesses caused by civilization such as cardiovascular diseases, metabolic disorders as well as disorders of the immune system, cancer, diabetes etc.

No chance for regeneration

Near infrared light is able to activate cytochrome oxidase, an important enzyme for the functioning of the mitochondria and therefore promotes wound healing and repairs tissue damages on a cellular scale. If one spends the biggest part of the day in mercury light and looks into computer screens for a long time the eyes get an overload of short-wave blue light. As this light lacks the proportions of red and infrared light responsible for enhancing blood circulation, the regeneration can often be insufficient.
Brightness control offers no protection

The brightness control of a screen works through pulse width modulation regulating the on-time of the source of light in a certain frequency. Even when reducing the brightness of the screen the pauses between the impulses indeed become longer, but the power of the impulses is not reduced. Therefore the light impulse always penetrates the body tissues to an equally deep level, even when the eye perceives a lower brightness caused by frequency modulation. Pulsating signals can disturb the biological balance even more than permanent signals. TFT screens only cease to flicker when turned on fully. That is why it is recommendable to turn the screens on fully and wear special Computer Protection Glasses from Prisma. Protect your eyesight!

In order to protect eyes from mechanical and chemical danger it is necessary and normal to wear protection glasses. But the danger caused by unprotected work at screens and under fluorescent lamps is often played down or denied by orthodox medicine although the above-mentioned damaging mechanisms have already been proven in cell experiments. Who wants to wait until – maybe only in many years from now - orthodox medicine research delivers the final proof? If you already want to protect yourself today, we recommend you to wear Prisma Computer Protection Glasses as a precaution.

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Sunglasses and Macular Degeneration​

Why wear sunglasses?

If you have a retinal disease, you are probably photosensitive, where too much direct light is painful for your eyes. You also have retinal cells that can be easily damaged by too much light, and some colors of light (even invisible light) have been shown to be hazardous. Additionally, reflected light and glare from horizontal surfaces serve only to compound your problems when you are already dealing with compromised vision.

The right sunglasses can eliminate all or most of these difficulties, allowing you to safely maximize your vision in bright environments. The endless array of choices, however, can be confounding. Hopefully, this article will help you to narrow your options and make your decisions easier.

What your sunglasses should do

1. Totally eliminate "ultraviolet" (UV) rays.

UV rays are of such high frequency that they cannot be seen by the human eye. They are short wavelengths measuring less than 400 nanometers (nm), as illustrated below.
UV rays are divided into two categories, UV-A and UV-B, with UV-A being the most intense. Your cornea absorbs all UV-B, and most UV-A. Over time, however, the UV-A that gets through can damage your lens and retina, so you want to be sure your sunglasses are labeled 100% UV-A and UV-B protective.

2. Reduce or eliminate blue light.

Blue light waves (400-500 nm) are responsible for the haze you see in bright sunlight, and a growing compendium of research is showing that this frequency can also be hazardous to the lens and retina. For a great deal of information on the effect of light on the retina, see "Artificial Lighting and the Blue Light Hazard (The Facts About Lighting and Vision)" in the MD Support Library.

To protect your eyes from blue light and to increase contrast, you need to look for specific tints:

* orange, red-orange = 100% protection (no visible blue)

* yellow, amber, gold, brown = Moderate protection (some visible blue)

Beware of any company that advertises 100% blue light protection by colors other than orange or red-orange. The best way to tell is to try them on. If you can see blue, they are not blue-blockers.

It is important that you realize how 100% blue-blockers will distort other colors. For this reason, you should not drive with them on. You will also find that your color perception will be out of kilter after removing them (yellow school busses will be a beautiful pink, for example). Don't worry, you will return to normal in a few minutes.

3. Reduce light intensity.

Changes in intensity are accomplished by differing levels of "darkness," or "transmission" of the lens. The amount of transmission depends upon your desired comfort and safety level. Be careful that you don't buy dark lenses that are not UV protective. Your eyes will naturally dilate in response to the low intensity, which will increase the amount of UV that enters.

4. Eliminate horizontal glare

Horizontal glare is reflection off of a surface such as water or a roadway. Poloraized lenses will take care of the problem.

5. Protect your eyes from all directions.

Your sunglasses should protect your eyes from the sides, above and below. This is done with shields on the top and sides, and facial contact at the bottom. If you wear prescription glasses, you can purchase “fitovers.” Or you can have your optometrist make prescription sunglasses that are smaller and contoured to your face. "Clip-on" lenses will not offer enough protection.

6. Extra features

The most important eye-safety concerns have been discussed, but you can also find features such as:

* Anti-reflective coating, to keep the sun from reflecting off the back of the lens into your eyes. This can be avoided for the most part by wearing a brimmed hat.

* Scratch-resistant coating, which is helpful, but it probably won’t protect the lenses from a drop onto concrete. (That’s why it’s only called "resistant.")

* Mirrored lenses, which reflect about 50% of light away from the eyes, allowing the other 50% to pass through. These scratch easily.

* Transition (photochromic) lenses, which actually change from dark to clear, depending upon the light. They operate, however, by sensing UV rays, so they will not work if you are sitting behind glass, such as in a car. Glass blocks UV.

Finally, your sunglasses should be comfortable, durable and as stylish as you like, but those personal decisions will affect only your pocketbook, not your eyes. You will find many styles and price ranges to choose from, and remember, cheap (under $20) probably means lesser quality, but expensive doesn’t always mean higher quality. Just be sure the lenses meet the requirements for good visual health.

Summary

To help organize all of this information, here is a summary for you to take to the store. Buy them if . . .

* You want 100% blue-blockers and they are tinted orange or red-orange. (You will see no blue through them.)

* You want partial blue-blockers and they are tinted yellow, amber, gold or brown. (You will see some, but not all, blue through them.)

* They have a label that says they block 100% UV-A and UV-B.

* They are not so dark as to hinder your safe mobility.

* They are polarized to eliminate horizontal glare.

* They protect against light from all sides.


Recommended brands

Here are some dealers in sunglasses that follow honest advertising practices and meet the standards of safety for people with macular degeneration.

BluBlocker _http://www.blublocker.com/

Cocoon Eyewear _http://www.cocoonseyewear.com/

Jonathan Paul Eyewear _http://www.jpeyewear.com/

NoIR Medical Technologies _http://www.noir-medical.com/

For more details about the information in this article, see "How Sunglasses Work," by Jeff Tyson

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Blue Light Is Causing Blindness ?​

• Before the advent of artificial lighting, many went to bed and got up with the sun; lighting at night comes at a price as it affects health, interrupting sleep patterns, circadian rhythms and the perpetuation of animal species
• Data show blue light from digital devices activates retinal in your eye to attack macular photoreceptor cells, accelerating age-related macular degeneration, a leading cause of blindness
• Exposure to blue light also affects your ability to produce enough melatonin to achieve quality sleep, thus increasing your risk of heart disease, stroke, obesity and other health problems
• Data show vitamin E reduces damage from blue light; consider using blue light-blocking glasses while using digital devices, using LED lighting with safer rating, and eating foods high in omega-3 fats and anthocyanins to protect your sight