Seasonal Affective Disorder

Seasonal Affective Disorder

Shortly before the hype began about bright light therapy being an effective treatment for Seasonal Affective Disorder (SAD), pilot studies had been conducted on the use of bright light to treat nonseasonal major depression. These preliminary studies were inconclusive, and therefore did not generate the publicity that followed the initial studies on light treatment for SAD. We now know, from the SAD studies and studies on using light to treat circadian rhythm disorders, that the intensity of light in these initial studies was lower than the amounts found to be biologically active in humans.

Subsequent studies on light treatment for nonseasonal depression, which have made use of the findings from Seasonal Affective Disorder treatment, have shown overwhelmingly that bright light treatment successfully reduces depression scores by 12-35% for nonseasonal depression, this is quite affective. Significant benefit is often noted within 1 week or less. Strong evidence exists that bright light therapy can be used in conjunction with other therapies, such as antidepressants and partial sleep deprivation; in fact, the benefit of such combined treatments may actually be more affective than the added effects of the separate treatments. Benefit with bright light is often seen within the first week, but additional benefit is seen over the next several weeks. "Extended treatment beyond 4 weeks has not been studied systematically, but clinical experience indicates that many depressed patients benefit from incorporating bright light into their long-term living patterns."

It has been suggested that longer exposure times might be required for those with the disorder nonseasonal depression than for those with SAD, as this group may be less sensitive to bright light. However, patients taking psychiatric medications (e.g., tricyclics, tetracyclics, lithium) may be at increased risk of complications, as these medications cause photosensitivity, so extreme caution should be exercised, and such patients should be closely monitored by their health professionals when undertaking light therapy.

It has been suggested that several groups of nonseasonally depressed people may particularly benefit from bright light treatment. Elderly people, especially those in community-living residences, often are exposed to little or no bright light, and may experience problems with their circadian rhythms as well as depression. With the abundance of medications this population already take, the side effects and interactions of many medications, and the fact that hypnotic medications are often of little or no value to this age group, bright light treatment may be the optimal treatment for both their circadian rhythm disorder and their depression.

Since light treatment is a non-pharmacologic treatment, it may be better tolerated or more affective in patients who decline medication treatment due to side effects, compliance issues, or drug intolerance. For those with adolescent-onset bipolar disorder, light therapy could be a useful adjunct to other treatments.