Treatment of Seasonal Depression with Bright Light Therapy by Wes Weidle, PA-C, CAQ-PSY

Seasonal Affective Disorder is a term used to describe depressive episodes that follow seasonal patterns, most commonly beginning in the late fall and early winter months, with resolution in the spring and summer months. Symptoms may include feeling hopeless or worthless, losing interest in activities that are normally pleasurable, decreased energy, changes in appetite or weight, changes in sleep patterns, and/or thoughts of suicide or death. 

According to the National Institute of Mental Health (NIMH), some theories behind the phenomenon of seasonal depression include dysregulation of serotonin (an important brain chemical involving mood), overproduction of melatonin, and underproduction of Vitamin D. Possible treatments for seasonal depression include antidepressants, Vitamin D supplementation, psychotherapy, and bright light therapy. 

Artificial bright light therapy has been proven effective in numerous randomized clinical trials and may be a good option if medications are not tolerable or effective. Most studies show that about 60% of patients respond to this type of therapy.  Positive effects of bright light therapy are obtained if utilized in the early morning hours for a duration of 30 minutes. In order to show clinically significant improvement in symptoms, the light must reach an intensity of 10,000 lux and include fluorescent bulbs emitting white light specifically. Lower intensity light may be helpful but requires a longer duration of exposure. Typically, UV light is filtered out from most light boxes, reducing potential risks to the eyes and skin. Ideally, the light box should be about 16 to 31 inches away from the individual and be projected slightly downwards. 

If symptoms do not improve within 2 to 4 weeks, adding afternoon/evening bright light therapy for an additional 30 minutes may be helpful. Light therapy is generally safe and there are no absolute medical contraindications. There is little to no evidence that bright light therapy causes any retinal damage in humans, according to www.uptodate.com. The most common side effects include eye strain and headaches. It should be noted that patients with bipolar major depression may be at increased risk for manic episodes with the initiation of bright light therapy due to its stimulating properties. 

In review, bright light therapy appears to be an excellent option for the treatment of seasonal depression if administered correctly - that is, with the correct intensity of light and for an adequate amount of time. Given its safe profile with minimal side effects, this provides a therapeutic opportunity to improve mood without the common side effects associated with most antidepressant medications.