Review: bright light therapy and dawn simulation reduce symptom severity in seasonal affective disorder.

M e t h o d s Data sources: MEDLINE (1975 to July 2003), the Cochrane Library, and bibliographies of relevant reviews and studies. Study selection and assessment: Englishlanguage randomized controlled trials (RCTs) of adults 18 to 65 years of age with a diagnosis of mood disorder based on DSMIII, DSM-III-R, DSM-IV, Research Diagnostic Criteria, or the Rosenthal criteria, who were in the acute phase of treatment. Treatment conditions had to meet the following minimum dose criteria: bright-light therapy for seasonal affective disorder (≥ 4 d of ≥ 3000 lux-h) vs placebo (≤ 300 lux); dawn simulation (increasing light exposure from 0 to 200 to 300 lux over 1 to 2.5 h) vs placebo (< 5 lux increase or < 15 min duration); and bright-light augmentation (≥ 4 d of ≥ 3000 lux-h and bright-light therapy as the primary adjunct to standard therapy). Outcomes: Psychiatric symptom measures (e.g., Hamilton Depression Rating scale, Seasonal Affective Disorders Version). M a i n r e s u l t s 20 RCTs (n = 693) met the inclusion criteria and had sufficient data to calculate mean scores and standard deviations. Meta-analyses showed that bright-light therapy and dawn simulation reduced depressive symptom severity more than placebo for seasonal affective disorder (Table). Bright-light therapy also reduced symptom severity more than placebo for nonseasonal depression (Table) but not when used as an adjunct to pharmacotherapy. Analysis of 4 trials that included data on remission (i.e., scores ≤ 8 on Hamilton Depression Rating Scale) showed increased remission with bright-light therapy in patients with seasonal affective disorder (odds ratio 2.9, 95% CI 1.6 to 5.4). C o n c l u s i o n s Bright-light therapy reduces the severity of depressive symptoms more than placebo for seasonal affective disorder and nonseasonal depression. Dawn simulation reduces symptom severity for seasonal affective disorder. Bright-light therapy as an adjunct to standard pharmacotherapy does not differ from placebo for nonseasonal depression.