Dawn simulation and bright light in the treatment of SAD: A controlled study

Background: Some small controlled studies have found that dawn simulation i s effective in treating seasonal affective disorder (SAD). With a larger sa mple size and a longer duration of treatment, we compared dawn simulation w ith bright light therapy and a placebo condition in patients with SAD. Method: Medication-free patients with SAD were randomly assigned to one of three conditions: bright light therapy (10,000 lux for 30 min, from 6:00 Am to 6:30 AM), dawn simulation (1.5 hour dawn signal from 4:30 AM to 6:00 AM peaking at 250 lux), and a placebo condition, a dim red light (1.5 hour da wn signal from 4:30 AM to 6:00 AM peaking at 0.5 lux.) Over the subsequent 6 weeks, the subjects were blindly rated by a psychiatrist using the Struct ured Interview Guide for the Hamilton Depression Rating-Seasonal Affective Disorder Version (SIGH-SAD). We modeled the profiles of the remissions (SIG H-SAD less than or equal to 8) and response ( greater than or equal to 50% decrease in SIGH-SAD) to treatment over time using Cox proportional hazards models. Results: The sample consisted of 95 subjects who were randomized to the thr ee conditions: bright light (n = 33), dawn simulation (n = 31) and placebo (n = 31). Dawn simulation was associated with greater remission (p < .05) a nd response (p < .001) rates compared to the placebo. Bright light did not differ significantly from the placebo. Dawn simulation was associated with greater remission (p < .01) and response (p < .001) rates compared to the b right light therapy. The mean daily hours of sunshine during the week befor e each visit were associated with a significant increase in likelihood of b oth remission (p < .001) and response (p < .001). Conclusions: Dawn simulation was associated with greater remission and resp onse rates compared to the placebo and compared to bright light therapy. Th e hours of sunshine during the week before each assessment were associated with a positive clinical response. (C) 2001 Society of Biological Psychiatr y.