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Source: Magnusson A, Boivin D. Seasonal affective disorder: An overview. Chronobiol Int 2003;20:189-207. Avery D. A turning point for seasonal affective disorder and light therapy research? Arch Gen Psych 1998;55:863-864.
Abstract: Seasonal affective disorder (SAD) is a condition of regularly occurring depressions in winter with a remission the following spring or summer. In addition to depressed mood, the patients tend to experience increased appetite and an increased duration of sleep during the winter. The pathological mechanisms underlying SAD are incompletely understood. Certain neurotransmitters have been implicated; a dysfunction in the serotonin system in particular has been demonstrated by a variety of approaches. The role of circadian rhythms in SAD needs to be clarified. The phase-delay hypothesis holds that SAD patients’ circadian rhythms are delayed relative to the sleep/wake or rest/activity cycle. This hypothesis predicts that the symptoms of SAD will improve if the circadian rhythms can be phase-advanced. There is some experimental support for this. SAD can be treated successfully with light therapy. Other forms of light treatments, pharmacotherapy, and other therapies are currently being tested for SAD.
Source: Eastman C, et al. Bright light treatment of winter depression. Arch Gen Psych 1998;55:883-889.
Abstract: Bright light therapy is the recommended treatment for winter SAD. However, the studies with the best placebo controls have not been able to demonstrate that light treatment has a benefit beyond its placebo effect. Ninety-six patients with SAD were randomly assigned to one of three treatments for four weeks. Depression ratings using the Structured Interview Guide for the Hamilton Depression Rating Scale, SAD version (SIGH-SAD) were performed weekly. There were no differences among the three groups in expectation ratings or mean depression scores after four weeks of treatment. However, strict response criteria revealed statistically significant differences; after three weeks of treatment morning light produced more of the complete or almost complete remissions than placebo. Bright light therapy had a specific antidepressant effect beyond its placebo effect, but it took at least three weeks for a significant effect to develop. The benefit of light over placebo was in producing more of the full remissions.
Comments by Mary L. Hardy, MD
Most of us feel like we get the "winter blues" to some degree, but seasonal affective disorder (SAD), defined in the DSM-IV as recurrent depression with a seasonal pattern, is a more serious condition. All the typical symptoms of depression are present (fatigue, change in appetite and sleep patterns, depressed mood), but they begin with the decrease in light in fall or early winter and resolve during the spring. SAD is most common among women of childbearing years. In the United States, SAD has been reported to be more prevalent the further north one lives. SAD has been documented internationally with prevalence rates varying from less than 1% to almost 10%.1 In the United States, this can mean that as many as 10 million people suffer from SAD. Patients with SAD also are much more likely to suffer from other types of cyclic depression such as premenstrual dysphoric syndrome.2
Although the accepted therapy for SAD disorder since the 1980s has been exposure to bright light (2,000-10,000 lux) for 30 to 120 minutes per day during the winter, methodological questions limited the implementation and widespread acceptance of this recommendation.3 Two recent, well-designed studies in the Archives of Psychiatry both support the use of bright light therapy and demonstrate that morning exposure is superior to evening treatment. A placebo-controlled trial of 96 patients with SAD during the winter in Chicago was performed to compare an early morning light treatment vs. an evening light treatment to a dummy placebo treatment.4 Previous trials had used a low light source as a control for bright light therapy. This was not an ideal placebo, because patients could not be blinded and their expectation of benefit could distort the outcome. This trial used a dummy placebo that emitted negative ions and buzzed. Patients were told that infrared light was being tested and this deception seemed to correct for patient expectation. Therapy consisted of 1.5 hours exposure per day to a 6,000 lux light source beginning at either 6 a.m. or 9 p.m. for four weeks. Sixty-one percent of the morning-treated patients improved their depression rating by more than 50% compared to 50% of the evening patients and 32% of the placebo patients. Significant effects were not seen before three weeks of treatment in this study.
A second trial in the same issue of the Archives of General Psychiatry looked directly at the comparison of morning vs. evening light therapy.5 Fifty-one patients with SAD were matched with 49 control subjects in a crossover trial. Initially the patients were randomized to be exposed to either two hours per day of bright light therapy (2,500 lux) early (from 6-8 a.m.) or later (from 7-9 p.m.). After two weeks of initial therapy the groups were withdrawn from light therapy for a week and then exposed to the alternate schedule. Melatonin levels also were measured weekly during the course of the trial. Early morning treatment was significantly more effective than evening therapy (P < 0.001). Remission was recorded in 37% of the morning-treated patients but in only 6% of the evening-treated patients. Early morning light also was more effective in normalizing the melatonin response in those patients. This trial showed positive results despite the relatively low intensity light and shorter duration of therapy. It would be expected from reading other studies that the percentage of positive responders would increase as treatment continued.
This therapy is well-tolerated by patients and the major difficulty is getting up early enough to have the 1.5 to 2 hour exposure before starting a regular workday. Limited evidence also suggests that early morning light exposure may be helpful in other types of episodic depression, which are problematic for women. Positive results have been reported in small trials of women with antepartum6 and postpartum depression,7 as well as late luteal phase dysphoric disorder.8
Implementation of therapy is facilitated by the wide variety of vendors and light sources currently available. (See resources.) Classically, patients would sit close to a powerful light box consisting of several tubes the size of a florescent light bulb. These were bulky, expensive, and difficult to use outside of the house. Newer devices are more compact and convenient. Early clinical trial results show promise for an alarm clock that stimulates dawn by increasing the amount of light in the room in the 1-2 hours prior to arising. This device, if it proves to be as effective as a standard light box, could greatly improve patient compliance. Current devices cost between $100-250.
In summary, for those patients who have an exaggerated response to winter darkness, we should consider light therapy. Recommended therapy consists of morning exposure to a light source of at least 2,000 lux for 30-120 minutes. Sources greater than 10,000 lux are less well tolerated and are more expensive. Therapy should be initiated at the earliest signs of negative effect on mood and stopped as the winter ends. Poor or no response in four weeks should trigger a re-evaluation of the therapy.
Light therapy is easy, well tolerated, and effective. For our patients who struggle with this insidious problem, this really could be the dawning of a whole new day.
Dr. Hardy, Medical Director Cedars-Sinai Integrative Medicine Medical Group Los Angeles, CA, is on the Editorial Advisory Board of Alternative Therapies in Women’s Health.
1. Magnusson A. An overview of epidemiological studies on seasonal affective disorder. Acta Psychiatr Scand 2000;101:176-184.
2. Praschak-Reider N, et al. Prevalence of premenstrual dysphoric disorder in female patients with seasonal affective disorder. J Affective Disorder 2001;63: 239-242.
3. Magnusson A, Boivin D. Seasonal affective disorder: An overview. Chronobiol Int 2003; 20:189-207; Avery D. A turning point for Seasonal Affective Disorder and light therapy research? Arch Gen Psych 1998;55: 863-864.
4. Eastman C, et al. Bright light treatment of winter depression. Arch Gen Psych 1998;55:883-889.
5. Lewy AJ, et al. Morning vs. evening light treatment for patients with winter depression. Arch Gen Psych 1998;55:890-896.
6. Oren DA, et al. An open trial of morning light therapy for treatment of antepartum depression. Am J Psychiatry 2002;159:666-669.
7. Corral M, Kostaras D. Bright light therapy’s effect on postpartum depression. Am J Psychiatry 2000;157: 303-304.
8. Lam RW, et al. A controlled study of light therapy in women with late luteal phase dysphoric disorder. Psychiatry Res 1999;86:185-192.