Shedding Light on SADness: Seasonal Affective Disorder

Shedding Light on SADness: Seasonal Affective Disorder

Light from the sun has nourished humanity for millions of years. In addition to food, air, and water, sunlight is the most important survival factor in human life.

Ancient Egyptian and Greek civilizations worshipped the sun for its healing powers and used its full spectrum of light to treat physical and mental problems in a practice known as heliotherapy.

The effects of the seasons on humans were well known by the ancients but were largely forgotten by modem medical practitioners until recently. Over the centuries the circadian rhythms of our bodies have been shaped by the cycles of night and day, of darkness and light, of cold and warmth. However, the dawn of the Industrial Age brought significant changes to these rhythms. Up to about 100 years ago, 90 percent of the world's population spent most of their time outdoors in the sunshine. While we continue to respond to the rhythms of the seasons and of the sun and the moon, our lives have been somewhat disrupted by the lifestyle changes created by indoor lighting, and working indoors.

The season of SADness

Seasonal change beginning in September (or sometimes in late August in places far north of the equator), can cause some people who are more highly sensitive to the loss of natural light to become depressed, fatigued and run-down. More than 5,000,000 Americans experience what is known as Seasonal Affective Disorder (SAD) and more than 25 million get the milder form commonly called the "winter blues." Sufferers may endure most of the following symptoms: constant sleepiness, oversleeping, fatigue, overeating, craving carbohydrates, lethargy, irritability, depression, stomach problems, restlessness, lowered resistance to infection. These symptoms can last until April and are at their worst in the darkest months.

What causes SAD? It is not a psychosomatic or imaginary illness. The problem stems from the lack of bright light in winter. Researchers have proven that bright light makes a difference to the brain chemistry. It is known that the nerve centers in our brains controlling our daily rhythms and moods are stimulated by the amount of light entering the eyes. During the night, the pineal gland produces a hormone, melatonin, which makes us drowsy. At daybreak, the bright light causes the gland to stop producing this melatonin. However, on dark winter days, especially indoors, not enough light is received to trigger the waking up process. Thus the sleep hormone is commonly overproduced by SAD sufferers. Exposure to bright light increases the production of the hormone called serotonin, a neurotransmitter of the brain that gives us the sense of well-being. Lack of enough serotonin is known to be a factor in depression.

Light therapy

For more than 40 years, John Nash Ott has studied the effect that light has on living things. Author of Health and Light (Devin-Adair, 1973), Light Radiation and You (Devin-Adair, 1982) and many scientific papers, Ott has concluded that "malillumination" is a growing problem in the modern world. Depression, fatigue, eyestrain, headaches, stress and feeling "out of sorts" can be attributed to poor lighting. The wrong lights, from Ott's point of view, are any lights that are not "full-spectrum" -- closest to the light of the sun.

As the cause of SAD or "winter blues" is lack of bright light, the treatment is to be in bright light every day by pulling back the curtains, opening the windows or by being outdoors. (Of course, going to a brightly-lit climate, whether skiing or somewhere hot, is also a cure). However this is not always possible or practical. So, more and more people are choosing the next best thing -- lighting up the interiors of their homes and public spaces with full-spectrum lighting. Studies have shown that those who work in offices with full-spectrum lighting report less eyestrain, fewer headaches, fewer sick days, and better concentration. In homes, people testify to having more energy, better sleep patterns and a reduction in the craving of carbohydrates and caffeine.

The clinical prescription for SAD patients is approximately 30 minutes to an hour sitting in front of a light box of full-spectrum lamps of 10,000 lux (the measurement of light), allowing the light to reach the eyes.

Full-spectrum lights include the full range of rays from ultraviolet (UV) to infrared, with rainbow colors violet, indigo, blue, green, yellow, orange, and red in between. Incandescent lights, the familiar bulbs that we twist into sockets, are deficient in the blue end of the spectrum and emit an abundance of yellow and red which can cause glare and eyestrain. Standard fluorescent lights found in many businesses, factories, hospitals, schools and offices are even more deficient. The cool-white bulbs miss much of the red, blue, and violet part of the spectrum where the sun's emission is the strongest.

UV factor

Proponents of full-spectrum lighting are concerned about the bad press given to ultraviolet rays. The study most responsible for the fear of UV was conducted in the Medical College of Virginia, Richmond. Reported in 1981, clinical tests involved submitting animals under the most inhumane and extreme measures to "prove" that UV light causes cataracts, retinal damage and skin cancer. By contrast, a less publicized report appeared in the British medical journal Lancet, 1982, which noted that Australian office workers working under fluorescent lights had higher incidents of skin cancer than those who worked outside. Adding to the confusion around UV is the tendency of mass media to put all types of UV radiation in the same negative light. In fact, there are three types: UV-A, which is responsible for tanning; UV-B, crucial to the body's synthesis of vitamin D; and UV-C, a potent germicide. Of the three forms, UV-C poses the most potential for harm to life on earth because today's thinner ozone layer filters out fewer UV-C rays than it did during the millions of years during which human life evolved. Humans are most often exposed to UV-A when outdoors in the sun.

With experts so divided over the value of UV light, it's no wonder some consumers are confused. Many people are deterred from switching to full-spectrum lighting because of fear of the UV part of the spectrum. But, like most aspects of life and health, it's a matter of the right dosage, of achieving balance. What's ideal is a perfectly balanced white light that simulates sunlight. Such a light will have a color rendition index (CRI) of 90 or above.

A bright future

Perhaps the most promising area of light research is in the field of medicine. Many mainstream scientists are experimenting with the use of light to destroy viruses causing AIDS and other infectious diseases, as well as to decontaminate blood for transfusion. In the foreseeable future, photodynamic therapy, alone or in combination with other conventional techniques, will be able to successfully treat most, if not all, cancers and other life-threatening diseases.

Measurements & Data Corporation.


By Vicki Elmore


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