SUBJECTIVE DEGREE OF IMPROVEMENT IN SUMMER VERSUS AFTER LIGHT TREATMENT IN WINTER IN PATIENTS WITH SEASONAL AFFECTIVE DISORDER

Background: Seasonal affective disorder, winter type (SAD) is a condition characterized by recurrent episodes of depression in fall/winter, with remission in spring/ summer. Light treatment is a safe and effective intervention for SAD. Objective: To compare the subjective degree of mood improvement in summer with the subjective degree of improvement after light treatment in winter in patients with seasonal affective disorder, winter type (SAD). Method: Twenty-three patients (15 females and 8 males, average age 42.1, SD: 11.7) took part in the study. Their degree of improvement after light and summer was assessed using visual analogue scales administered in both winter after light treatment as well as summer. Improvement in summer and on-light in winter were compared using Wilcoxon Signed Ranks Tests. Results: Self ratings in both winter and summer consistently pointed towards a subjective more complete improvement in summer that after light treatment in winter (p<0.01). Conclusion: There is room for a more complete improvement in SAD patients receiving light treatment in winter. Differences (in intensity, spectral distribution, duration, angle and timing of exposure), between the ambient light of summer and a a light treatment device , as well as other potentially interactive biological, psychological, and socio-economic factors may account for a more complete improvement in summer in SAD patients.