The theoretical part of this thesis contains information on the application of bright light therapy. The empirical part consists of an extended follow-up survey on the application of light therapy in German speaking countries and contains data and results of this survey. These are compared to the results of a study by Kasper et al. (1994). The major findings are a) a substantial increase in the use of bright light therapy from 13.0% to 69.8% with no differences between Germany, Austria, and Switzerland, b) this increase is mostly due to treatment of various forms of depression while further possible applications are neglected, c) there is a shift in the usage of light therapy from monotherapy to combination of pharmacotherapy with bright light therapy as an adjunctive treatment, and d) a North-South-comparison showed no substantial differences. Data also suggest a lack of information concerning possible further applications and a wide range of interinstitutional application. Thus, promotion and information is needed, for bright light therapy fullfills all criteria of an evidence based treatment.