Key Takeaway
Morning bright light therapy is highly effective for seasonal affective disorder, with early morning exposure (soon after waking) showing best results.
Summary
This rigorous RCT examined bright light therapy for seasonal affective disorder (SAD), comparing morning light, evening light, and placebo. The study found that morning bright light exposure was significantly more effective than evening light or placebo for treating winter depression.
Importantly, earlier morning exposure (within 1 hour of waking) was more effective than later morning light. Response rates to morning light therapy exceeded 50%, making it comparable to antidepressant medications.
This study provides strong clinical evidence that the timing of light exposure matters, with morning light having superior effects on mood and circadian function.
Methods
- Randomized controlled trial
- 10,000 lux light box vs placebo ionizer
- Morning vs evening timing
- Standardized depression assessments
Key Results
- Morning light superior to evening light
- Earlier morning timing more effective
- >50% response rate
- Effects comparable to medications
Limitations
- SAD population specifically
- Artificial light box, not natural sunlight
- May not fully generalize to healthy individuals