Light therapy for SAD: Looking on the Bright Side

While many look forward to the crisp and clear autumn and winter months, others find that they struggle through these months feeling tired and low. Seasonal Affective Disorder, also known as SAD, is a form of depression that is brought on when levels of natural sunlight are reduced. Symptoms tend to begin as the days get shorter and winter draws in, only lifting completely during the summer months. A milder form of seasonal depression – often called sub-syndromal SAD (S-SAD) or simply ‘the winter blues’ – affects around 1 in 10 adults.

Bright Light Therapy

SAD is a form of depression that is brought on when levels of natural sunlight are reduced

I was interested to read a recent Swedish study that tested a treatment called ‘bright light therapy’ on individuals with SAD and with S-SAD (1). Bright light therapy is a treatment that involves exposure to a special light that mimics natural outdoor light.

The study tested the effects of the light therapy on 49 individuals who had been diagnosed with either SAD or S-SAD.

When the individuals began to experience winter depressive symptoms, some of the group were either given a 10-day course of bright light therapy, or were put onto a 3-week waiting list, after which they were given the 10-day treatment course. The group of people on the waiting list were used as the ‘control’ group for this study.

The study found that bright light therapy was linked to improvements in a number of symptoms. The researchers had conducted an earlier randomised clinical trial which found that bright light therapy did indeed have a positive effect on depressive mood in those with SAD and S-SAD (2). This new study, however, also measured the effects of bright light therapy on other symptoms, such as tiredness, fatigue, sleep problems and health-related quality of life. All of these symptoms had improved after the 10-day course of light therapy. Symptoms were then measured again, a month after the treatment had finished, and it was found that the symptom improvements had lasted.

The study suffers because, although a control group was used, strictly speaking there was no placebo group. If the second group had been exposed to a ‘placebo’ light rather than the therapeutic bright light, then this might have served as a better comparison group. The study is nevertheless very interesting because it indicates that light therapy can help not just depressive mood, but that it can bring about improvement in a number of symptoms including milder symptoms of depression and daytime sleepiness.

Despite the design flaw in the study, light therapy does appear to be a promising treatment for the ‘winter blues’. Systematic reviews have reported that light therapy represents an effective and well-tolerated treatment for SAD (3). A home light box may therefore be a wise investment for those who need a boost during these darker months. Using a light box for between 30 minutes to an hour in the morning is considered to be an effective approach, and the light should be at least 2500 lux to be beneficial. Some individuals also use a Sunrise Alarm Clock as well to help balance their circadian rhythm and ensure they wake naturally in the morning rather than to the sharp, shrill noise of a standard alarm clock. These Wake-Up Lights simulate the “sunrise” so the brain wakes gradually.

Seasonal affective disorder, or the milder ‘winter blues’ can mean months of misery for those affected. With an estimated 1 in 20 adults affected by SAD, and a further 1 in 10 suffering from its milder form S-SAD, it is certainly an approach worth considering.

Written by Nadia Mason

References
1. Rastad C, et al. Improvement in Fatigue, Sleepiness, and Health-Related Quality of Life with Bright Light Treatment in Persons with Seasonal Affective Disorder and Subsyndromal SAD. Depression Research and Treatment. 2011:543906
2. Rastad C, Ulfberg J, Lindberg P. Light room therapy effective in mild forms of seasonal affective disorder—a randomised controlled study. Journal of Affective Disorders. 2008. 108(3):291–296.
3. Lee T M, Chan C C. Dose-response relationship of phototherapy for seasonal affective disorder: a meta-analysis. Acta Psychiatrica Scandinavica 2000. 99(5): 315-323

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