Overview

LED Light waves 2 (3 sinusoidal waves at the same frequency, but out of phase)

This information has been compiled as a handbook for the clinical use of LED therapy. Although it includes a short overview of physics, physiology, and the history of light, these subjects have been purposely limited to maintain the focus on the clinical aspects of laser therapy.

History

The ancient Greeks, Romans, and Egyptians used light therapy and applied heat to tender points in the human body to relieve symptoms of many syndromes.

In 1903, Nils Finsen, a Danish medical doctor, was given the Nobel Prize for successfully treating tuberculosis, rickets and lupus vulgaris with ultraviolet light. This was the first recognized application of artificial light to cure disease.

In 1923, the Russian researcher Alexander Gurwitsch first detected that cells emit infrared light as a means of intercellular communication. He observed that this light could be transmitted from a test tube to another adjacent one without any physical contact between them. He termed this infrared emission “mitogenetic radiation.”

In 1967, Dr. Endre Mester, a professor of surgery in Hungary, performed a revolutionary series of experiments that first documented the healing effect of lasers. In his earliest study, he discovered that tissue growth was accelerated with laser therapy. His later experiments documented not only improved healing with light therapy but also demonstrated that the healing was a systemic and not a local phenomenon. His work stimulated many other researchers in Europe and Eastern Europe to appreciate the value of laser therapy, long before it was appreciated in Asia, Africa, and the Americas.

In 1923, the Russian researcher Alexander Gurwitsch first detected that cells emit infrared light as a means of intercellular communication. He observed that this light could be transmitted from a test tube to another adjacent one without any physical contact between them. He termed this infrared emission “mitogenetic radiation.”

In 1967, Dr. Endre Mester, a professor of surgery in Hungary, performed a revolutionary series of experiments that first documented the healing effect of lasers. In his earliest study, he discovered that tissue growth was accelerated with laser therapy. His later experiments documented not only improved healing with light therapy but also demonstrated that the healing was a systemic and not a local phenomenon. His work stimulated many other researchers in Europe and Eastern Europe to appreciate the value of laser therapy, long before it was appreciated in Asia, Africa, and the Americas.

Seasonal affective disorder: bring on the light

Michael Craig Miller, M.D.
Senior Editor, Mental Health Publishing
POSTED DECEMBER 21, 2012, 8:50 AM , UPDATED OCTOBER 29, 2015, 8:36 PM

Assuming that the Mayan calendar mania was wrong and the world spins madly on, today marks the shortest daytime of the year in the northern hemisphere. In Boston, we get just nine hours of daylight; Barrow, Alaska doesn’t get any. Although the winter solstice marks a seasonal turning point, with daylight getting incrementally longer from here until June 21, for people with seasonal affective disorder it’s just another day of feeling lousy.

People with this condition lose steam when the days get shorter and the nights longer. Symptoms of seasonal affective disorder include loss of pleasure and energy, feelings of worthlessness, inability to concentrate, and uncontrollable urges to eat sugar and high-carbohydrate foods. Although they fade with the arrival of spring, seasonal affective disorder can leave you overweight, out of shape, and with strained relationships and employment woes.

We don’t know exactly why seasonal affective disorder occurs. According to a review published in the current issue of American Family Physician, there are probably several different causes, including changes in the body’s natural daily rhythms (circadian rhythms), in the eyes’ sensitivity to light, and in how chemical messengers like serotonin function.

Some people find that taking an antidepressant medication helps. A unique approach is the use of light therapy.


The value of light

If lack of sunlight causes or contributes to seasonal affective disorder, then getting more light may reverse it. Bright light works by stimulating cells in the retina that connect to the hypothalamus, a part of the brain that helps control circadian rhythms. Activating the hypothalamus at a certain time every day can restore a normal circadian rhythm and thus banish seasonal symptoms.

Light therapy entails sitting close to a special “light box” for 30 minutes a day, usually as soon after waking up as possible. These boxes provide 10,000 lux (“lux” is a measure of light intensity). That’s about 100 times brighter than usual indoor lighting; a bright sunny day is 50,000 lux or more. You need to have your eyes open, but don’t look at the light. Many people use the time to read a newspaper, book, or magazine, or catch up on work.

Although light therapy is at least as effective as antidepressant medications for treating seasonal affective disorder, it doesn’t work or isn’t appropriate for everyone. Some people need more light, or brighter light. Others can’t tolerate bright light—in people with bipolar disorder, for example, it can trigger hypomania or mania. And even though the risk of eye damage from bright light is low, anyone with diabetes (which can damage the retina) or pre-existing eye disease should check with a doctor before trying light therapy.

In efforts to make light therapy more effective, researchers are looking to improve it in various ways. One approach is creating light boxes that simulate dawn and sunrise, gradually increasing in intensity from darkness to 300 lux. Another involves using lower intensity blue light, which has a more powerful effect on the retina than white light.

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