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 .
A randomized controlled trial of cognitive-behavioral therapy, light therapy, and their combination for seasonal affective disorder.
This first controlled psychotherapy trial for seasonal affective disorder ( SAD ) compared SAD-tailored cognitive-behavioral therapy ( CBT ) , light therapy ( LT ) , and their combination to a concurrent wait-list control . Adults ( N = 61 ) with major depression , recurrent with seasonal pattern , were r and omized to one of four 6-week conditions : CBT ( 1.5-hr twice-weekly group therapy ) , LT ( 10,000-lux for 90-min/day with administration time individually adjusted ) , combined CBT + LT , or a minimal contact/delayed LT control ( MCDT ; LT following 6 weeks of monitoring ) . CBT , LT , and CBT + LT significantly and comparably improved depression severity relative to MCDT in intent-to-treat and completer sample s. CBT + LT ( 73 % ) had a significantly higher remission rate than MCDT ( 20 % ) . Using prospect ively measured summer mood status to estimate the " functional " population , CBT + LT also had a significantly larger proportion of participants with clinical ly significant change over treatment compared with MCDT . The LT condition outcomes virtually replicated results from prior trials . CBT , alone or combined with LT , holds promise as an efficacious SAD treatment and warrants further study . If replicated , CBT + LT 's  remission rate would represent a clinical ly meaningful improvement over the 53 % observed across LT studies
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 .