First-Line Treatment for Seasonal Affective Disorder
Light therapy at 10,000 lux for 30 minutes every morning is the first-line treatment for seasonal affective disorder. 1
Light Therapy Protocol
Morning light therapy is the standard approach and should be administered at the same time daily. 1, 2 The specific dosing parameters are:
- 10,000 lux for 30 minutes daily, OR
- 2,500 lux for 2 hours daily 1
Morning administration has proven superior to evening treatment in clinical trials. 1, 3 The timing matters because light therapy works by resetting circadian rhythms and modulating serotonin reuptake. 4
Expected Efficacy
Light therapy achieves approximately 80% response rates in selected patient populations, with atypical depressive symptoms (hypersomnia, hyperphagia, carbohydrate craving) being the strongest predictor of favorable outcomes. 3 Meta-analysis data demonstrate a standardized mean difference of -0.37 for depression ratings and a risk ratio of 1.42 for treatment response compared to placebo. 5
Safety Monitoring
Monitor closely for emergent hypomania in the first few days of treatment—this is the most significant risk. 1 Other side effects are generally mild and self-limiting:
- Eyestrain, nausea, and agitation typically resolve spontaneously 1
- Patients with pre-existing eye disease or those taking photosensitizing medications require periodic ophthalmologic and dermatologic monitoring 1
Alternative and Adjunctive Options
If light therapy alone is insufficient or not tolerated, consider:
- Antidepressants: SSRIs (fluoxetine, sertraline) and bupropion have demonstrated efficacy in double-blind, placebo-controlled trials 2, 3
- Cognitive behavioral therapy: Can be used alone or combined with light therapy 2
- Bupropion specifically: Has the strongest evidence for long-term preventive use if SAD recurs annually 2
Lifestyle Adjuncts
Increase exercise and natural light exposure as supportive measures, though these should not replace light therapy as the primary intervention. 2
Common Pitfall
Do not prescribe vitamin D supplementation as a primary treatment—evidence for its efficacy remains inconclusive despite its intuitive appeal. 2