Overall , both forms of preventive light therapy reduced the incidence of SAD numerically compared with no light therapy .
BACKGROUND Seasonal affective disorder ( SAD ) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring .
The prevalence of SAD ranges from 1.5 % to 9 % , depending on latitude .
The predictable seasonal aspect of SAD provides a promising opportunity for prevention .
This review - one of four review s on efficacy and safety of interventions to prevent SAD - focuses on light therapy as a preventive intervention .
Light therapy is a non-pharmacological treatment that exposes people to artificial light .
Mode of delivery ( e.g. visors , light boxes ) and form of light ( e.g. bright white light ) vary .
OBJECTIVES To assess the efficacy and safety of light therapy ( in comparison with no treatment , other types of light therapy , second-generation antidepressants , melatonin , agomelatine , psychological therapies , lifestyle interventions and negative ion generators ) in preventing SAD and improving patient-centred outcomes  among adults with a history of SAD .
The phototherapy light visor: more to it than meets the eye.
OBJECTIVE The purpose of the study was to ascertain whether phototherapy light visors provide an effective treatment for  seasonal affective disorder .  Previous studies have demonstrated a moderate response rate but have failed to find any difference in efficacy between light intensities . METHOD Subjects were r and omly assigned to receive , over a 2-week treatment period , 30 minutes of morning phototherapy with a light visor that emitted either a dim ( 30-lux ) red light or a bright ( 600-lux ) white light . Raters were blind to treatment , and patients were unaware of the alternatives . Response was assessed by using the structured 21-item Hamilton Depression Rating Scale , with an eight-item addendum for atypical depressive symptoms . Fifty-seven patients were enrolled across two sites . RESULTS Patients assigned to the different visors had similar baseline depression scores and similar expectations of outcome . Hamilton depression scale scores declined by 34.6 % for subjects given bright white light and by 40.9 % for subjects given dim red light .  Scores for atypical depressive symptoms fell by 44.1 % for patients assigned the bright white light visors and by 49.0 % for patients assigned the dim red light visors . Altogether , 39.3 % of the patients who received red light  and 41.4 % of the patients who received bright white light showed a full clinical response . CONCLUSIONS There were no significant differences in therapeutic response between patients who were treated with red or white light .  The results of this study suggest that the phototherapy light visor may function as an elaborate placebo . Alternative explanations , however , are considered
Overall , both forms of preventive light therapy reduced the incidence of SAD numerically compared with no light therapy .
BACKGROUND Seasonal affective disorder ( SAD ) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring .
The prevalence of SAD ranges from 1.5 % to 9 % , depending on latitude .
The predictable seasonal aspect of SAD provides a promising opportunity for prevention .
This review - one of four review s on efficacy and safety of interventions to prevent SAD - focuses on light therapy as a preventive intervention .
Light therapy is a non-pharmacological treatment that exposes people to artificial light .
Mode of delivery ( e.g. visors , light boxes ) and form of light ( e.g. bright white light ) vary .
OBJECTIVES To assess the efficacy and safety of light therapy ( in comparison with no treatment , other types of light therapy , second-generation antidepressants , melatonin , agomelatine , psychological therapies , lifestyle interventions and negative ion generators ) in preventing SAD and improving patient-centred outcomes  among adults with a history of SAD .