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Sunlight
and artificial light have been used for over a century to restore physical and
psychological health. More recently, medical science has come to recognize the
important role light plays in regulating the body's biological clock, which
controls sleep, hormone production, and other functions. Light therapy is now
used throughout the Western world to improve vitality and treat skin conditions
such as psoriasis. It is especially associated with seasonal affective disorder
(SAD), a severe manifestation of the "winter blues," thought to be caused by light deprivation in
winter.
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| HISTORY
The
benefits of natural sunlight have been used by generations of healers, notably
19th-century naturopaths. Danish doctor
Niels Finsen received the Nobel Prize for Medicine in 1903 for research into
the ability of ultraviolet light to treat tuberculosis. About fifty
years later, American photobiologist Dr. John Ott claimed that
"full-spectrum" light from the sun is needed for the body to absorb
key nutrients, and that pollution, windows, and eyeglasses may block vital
components of the sun's rays. The discovery that reduced daylight hours can
cause severe depression led to recognition of seasonal affective disorder. EVIDENCE & RESEARCH
Several
studies led by Dr. Norman E. Rosenthal, notably those published in the American
Journal of Psychiatry in the 1980s, are accepted as evidence that SAD
exists and can be treated by light therapy. The studies are supported by a
growing body of research. uv light is known to have antiviral,
antibacterial, and antifungal properties, and has proved effective in treating
psoriasis. Claims that it helps ailments such as heart disease, cancer,
osteoporosis, and menstrual problems are not yet backed by research.
SAD
may cause depression in winter, but many doctors believe the disorder is
relatively uncommon. For ailments such as psoriasis, uv light treatment
is conventional practice; for others, such as cancer, its efficacy is unproved.
Exposure to unfiltered uv rays must be weighed against the risk of skin
cancer.
CONSULTING
A PRACTITIONER
When
light enters the eye, it stimulates nerve impulses to the hypothalamus, part of
the brain responsible for mood, appetite, sleep, temperature, and sex drive.
These nerve impulses travel to the pineal gland in the brain, which regulates
hormonal balance, including the production of serotonin, a hormone linked to
mood. In darkness, the gland secretes melatonin, a hormone that controls sleep
patterns by causing drowsiness and is also said to affect the immune system. If
the body's internal clock is disrupted by jet lag, shift work, or seasonal
changes in light, physical or psychological problems may occur.
Natural
daylight also stimulates the body to produce vitamin D, essential for the
absorption of certain minerals, including calcium, which strengthens bones. The
uv rays in daylight have an antibacterial effect, thought to help clear
skin infections such as acne and psoriasis. A
practitioner places you under a fluorescent full-spectrum or bright white light
for up to an hour, depending on your condition. You can also use a light box and
visor at home for at least 20 minutes a day. Fluorescent full-spectrum light is
the same as natural daylight, but without the toxic uv wavelengths.
Bright white light (so called because the colors combine to make white)
contains no uv wavelengths - some studies suggest these are not needed
for an antidepressant effect.
Avoid overexposure to uv light, since it can
cause skin cancer.
Do not take vitamin D supplements during a
course of light therapy - high doses can be toxic.
Consult an eye specialist before a course of
light therapy if you have an eye disorder.
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