A CONTROLLED TRIAL OF TIMED BRIGHT LIGHT AND NEGATIVE AIR IONIZATION FOR TREATMENT OF WINTER DEPRESSION

Background: Artificial bright light presents a promising nonpharmacolo gical treatment for seasonal affective disorder. Past studies, however , have lacked adequate:placebo controls or sufficient power to detect group differences. The importance of time of day of treatment-specific ally, morning light superiority-has remained controversial. Methods: T his study used a morning X evening light crossover design balanced by parallel-group controls, in addition to a nonphotic control, negative air ionization. Subjects with seasonal affective disorder (N = 158) we re randomly assigned to 6 groups for 2 consecutive treatment periods, each 10 to 14 days. Light treatment sequences were morning-evening, ev ening-morning, morning-morning and evening-evening (10 000 lux, 30 min /d). Ion density was 2.7 X 10(6) (high) or 1.0 X 10(4) (low) ions per cubic centimeter (high-high and low-low sequences, 30 min/d in the mor ning). Results: Analysis of depression scale percentage change scores showed low-density ion response to be inferior to all other groups, wi th no other group differences. Response to evening light was reduced w hen preceded by treatment with morning light, the sole sequence effect . Stringent remission criteria, however, showed significantly higher r esponse to morning than evening light, regardless of treatment sequenc e. Conclusions: Bright light and high-density negative air ionization both appear to act as specific antidepressants in patients with season al affective disorder. Whether clinical improvement would be further e nhanced by their use in combination, or as adjuvants to medication, aw aits investigation.