Summer is my favorite season... the long sunny days just make me smile. But winter can leave me feeling blah. That’s why I have on occasion turned to mood-lifting light therapy—which basically consists of sitting in front of a special light-emitting device called a light box each morning—to chase away wintertime blues.
Why mention this now? Because recent research shows that light therapy relieves not only wintertime seasonal affective disorder (SAD), but also nonseasonal depression.
New evidence: In a study in Archives of General Psychiatry, one group of seniors (age 60 and up) with depression were exposed to the bright light of a light box for one hour daily for three weeks... the control group got a "sham" treatment with dim light. The bright-light group showed significantly greater improvement in mood and sleep quality (poor sleep often accompanies depression)... lower levels of the stress hormone cortisol... and more normal levels of melatonin, a hormone that helps regulate circadian rhythms and sleep-wake cycles by rising in the evening and falling in the morning. In fact, light therapy was as effective as antidepressant medication generally is—but did not carry the drugs’ risk for side effects.
I called Michael Terman, PhD, director of the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center, to ask who else could benefit from the treatment. He told me that bright-light therapy can successfully treat a number of nonseasonal forms of depression, including chronic depression in women and men of various ages... bipolar disorder... and depression during pregnancy (offering a safe alternative to medications that might affect the fetus). There is also preliminary evidence of light therapy’s positive effects for postpartum depression. According to Dr. Terman, light therapy alone relieves mild, moderate or even severe depression in some cases... in other cases, light therapy is used along with psychotherapy, medication and/or other treatments.
Eyes must be open during light therapy because it works through the eyes, not the skin. Dr. Terman explained that a simple neural pathway connects the retina to the area of the brain that houses the body’s internal clock. This clock is vulnerable to getting out of kilter with respect to the local time of day, which can cause mood and energy to plummet and make it hard to get to sleep or to wake up feeling alert. Bright-light therapy sends a signal that resets the internal clock, shifting the circadian rhythm so it is in sync with the local day/night cycle—and this in turn has positive effects on mood. In addition, if melatonin activity is high at the time of the light signal, a reaction is triggered that reduces melatonin secretion, thus reinforcing the corrective effects on the internal clock. Light therapy also may increase the availability of the mood-boosting neurotransmitter serotonin by reducing activity of a "transporter" molecule that removes serotonin from active sites in the nervous system.
Light therapy works surprisingly quickly. Effects may be seen within a week of daily use—and sometimes even faster, Dr. Terman said.
HOW TO DO IT
You do not need a prescription to purchase a light box, and for people with mild depression, light therapy self-treatment generally is safe, Dr. Terman said. However, certain people should use light therapy only under the supervision of a doctor. This includes anyone who...
- Suffers from moderate-to-severe depression, whether or not they are being treated with medication and/or psychotherapy—because if used incorrectly (such as at the wrong time of day), light therapy could potentially worsen depression symptoms.
- Has bipolar disorder—because if the condition is not being adequately treated with mood-stabilizing medication, light therapy could lead to mania... and because light therapy’s timing may need to be adjusted to later in the day so as not to destabilize the circadian rhythm.
- Takes medication that increases adverse reactions to sunlight, such as drugs used to control irregular heartbeat—because bright light could damage the retina, which absorbs these drugs in its photoreceptors.
- Has a degenerative eye problem, such as macular degeneration—because bright white light could accelerate illness progression. (In such cases, a dimmer "dawn simulation" device, which also has an antidepressant effect, may be used instead.)
Using a light box at home: Dr. Terman recommended buying a fluorescent light box that provides 10,000 lux of illumination, which is the type that has proven successful in clinical trials. (Lower lux levels can be effective, Dr. Terman said, but require more exposure time to get the same effect.) The light box should filter out ultraviolet rays that can damage eyes and skin... and should give off white light, not colored light. The Center for Environmental Therapeutics (CET), a nonprofit that Dr. Terman cofounded, offers an appropriate light box called the Daylight Simulator for $179.99 (www.CET.org). Some insurance companies cover the cost if patients are using the light box under a physician’s supervision.
Treatment typically involves sitting 12 inches from the light box for 30 minutes each day shortly after waking up. "It’s essentially a breakfast-time routine. You don’t look directly into the light, but your eyes are open and bathed in light while you concentrate, for example, on your newspaper or laptop," said Dr. Terman. Important: The optimal time for and duration of treatment sessions varies among individuals. To help you determine the appropriate time of day for your light therapy sessions based on your personal circadian rhythm, take CET’s free online Automated Morningness-Eveningness Questionnaire (see www.CET.org/eng/Tools_ENG.html and click on "your circadian rhythm type").
People whose depression is not limited to winter can benefit from using a light box year-round. Most people experience no negative side effects from light therapy. A small number of users develop headaches, eyestrain, agitation and/or mild nausea. These symptoms tend to subside after a few days, Dr. Terman said—but if symptoms persist, reducing the duration of light treatment sessions or sitting farther from the light box often takes care of the problem.
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