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Seasonal Affective Disorder and Light Box Therapy
Seasonal Affective Disorder (SAD) was initially described in 1984 by Rosenthal et al. in an article published in the Archives of General Psychiatry (1984; 41:72-80). It was first included in DSM-III-R as a modifier for codes for mood disorders that were felt to have a “seasonal pattern”. It continued as such in DSM-IV, and in DSM-5.
SAD describes patients who deny clinically-relevant mood symptoms most of the year, but who have recurrent mood symptoms during a certain time of year (most commonly, the winter months). Symptoms can include depressed mood, difficulty with waking in the morning, hypersomnia, hyperphagia with carbohydrate craving, low energy, difficulties with concentration, social isolation, and nausea.
Although the credibility of the diagnosis was initially disputed, it has since become a more widely accepted diagnosis. The prevalence of this condition ranges from approximately 1.5% to 9% of the US population, with a greater prevalence found in more northern latitudes, especially those with significant cloud cover during the winter months.
There are a number of theories about the causes of SAD, including that it is an evolutionary remnant, similar to the decreased level of activity in response to the decreased availability of food observed in other species.
A variety of treatments have been tried for SAD, and the most common one is bright light therapy. In this therapy, a light box produces 10,000 lux of “full spectrum” bright white light, and the patient sits in a location in which the light will fall on his or her face. However, the patient does not need to be staring at the light source.
Some studies have evaluated light at wavelengths in the blue-green portion of the visible spectrum (480 nm at 2,500 lux or 500 nm at 350 lux), but these studies have produced less consistent positive results.
If using 10,000 lux (which is approximately the intensity of being outside during mid-day on a sunny day), the recommended exposure is 30 to 60 minutes. The light source should be roughly within arms length to ensure adequate intensity (recall the old inverse square law of illumination, in which light intensity is inversely proportional to the square of the distance from the light source – so doubling the distance from the light reduces the intensity to one-fourth of the intensity at the original distance.).
In addition to bright light therapy, other treatments have been tried with varying levels of success including antidepressant medications, cognitive behavioral therapy, melatonin administration, exercise, and ionized-air administration.
In my practice in Indiana, I do see patients that meet criteria for SAD, but even more commonly I see patients who experience worsening of their depressive symptoms during the winter months. I will at times recommend bright light therapy, usually advising that patients try to obtain a light box from company that offers a return policy if they try it and feel that it is not effective for them. I also frequently modify their medication regimen, either increasing the dose of their antidepressant temporarily, or adding on an adjunctive agent during the months when the symptoms seem to be more pronounced.
Do you see SAD in your practice? If so, what strategies have you found helpful for your patients?
Reference
Chris Bojrab, MD, is the president of Indiana Health Group, the largest multidisciplinary behavioral health private practice in Indiana, established in 1987. He is a board certified psychiatrist and a Distinguished Fellow of the American Psychiatric Association who treats child, adolescent, adult, and geriatric patients. His areas of interest include psychopharmacology, sleep disorders, and gambling addiction. For more information and disclosures, visit www.chrisbojrabmd.com
The views expressed on this blog are solely those of the blog post author and do not necessarily reflect the views of Psych Congress Network or other Psych Congress Network authors.
