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For 20 years, bright white light therapy has been used to treat Seasonal Affective Disorder (S.A.D.). Studies have shown that it is as effective as antidepressant medication, and sometimes even more effective.
The standard dose is to sit in front of a 10,000 lux light for thirty minutes in the morning. Lux refers to the intensity of the light. A bright sunny day is 50,000 lux, regular indoor lighting is 100 lux.
Drawbacks to 10,000 Lux Light Therapy
- There are possible side effects, (see below) though for most people, they are minor.
- People may find it difficult to set aside thirty minutes to sit in front of the lights each day.
- Not everyone benefits from light therapy. Studies show that as many as 50% of people don’t benefit from light therapy, but some advances have been made. It has been found that timing may be an important factor in treatment. Melatonin is a hormone related to sleep. Everyone’s melatonin peaks at different times. Timing the dose in relation to the individual’s melatonin peak can increase effectiveness so that up to 80% of people benefit. But that still leaves 20% who receive no benefit. For those who need to experiment with timing, the nonprofit Center for Environmental Therapeutics offers a free online morningness-eveningness questionnaire test to help patients and therapists gauge the optimum time for therapy.
- Light therapy lights are not tested by FDA. It is recommended that consumers check to make sure that the light therapy box they choose has been used in reputable research facilities.
Risks and Side Effects of Light Therapy for S.A.D.
There are certain possible side effects to the standard bright white light therapy. They are:
- Manic episodes. Approximately one in five people with Seasonal Affective Disorder also have Bipolar Disorder. There is concern that light therapy may trigger a manic or hypomanic episode. Sometimes mood stabilizers are prescribed simultaneously to prevent this.
- Retinal damage. There is a small risk of retinal damage, though this risk is increased for certain populations.
Those populations at higher risk are:
- people taking lithium, which many people with Bipolar Disorder take;
- people taking first-generation antipsychotics, like Haldol, Halperon, Thorazine, and others;
- people taking melatonin or St. John’s wort;
- and those who have diabetes or certain diseases of the retina.
Blue Light Therapy and Dawn Simulation, as Possible Alternatives
Researchers are studying the use of blue light therapy, as a substitute for white light therapy. White light includes all colors of the light spectrum. But the retina is highly responsive to blue light. It is possible that the duration of exposure to blue light could be less than needed with white light. It is hoped that this will lessen the likelihood of retinal damage.
Another possible option is dawn simulation. A device known as a sunrise alarm clock simulates natural dawn lighting over a period of ninety minutes. It is thought that waking up to this light will eliminate symptoms of S.A.D. There are only a few studies, but they are promising.
It is recommended that the standard light therapy be tried first. There are a few drawbacks but most people will benefit. Side effects are possible but minimal, except for certain people. For those who do not benefit, either the timing or dosing can be tweaked, antidepressant drugs can be tried, or alternative treatments now being researched can be tried, like blue light therapy and dawn simulation.