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 .
Winter depression recurrence one year after cognitive-behavioral therapy, light therapy, or combination treatment.
The central public health challenge in the management of  seasonal affective disorder ( SAD ) is prevention of depression recurrence each fall/winter season . The need for time-limited treatments with enduring effects is underscored by question able long-term compliance with clinical practice guidelines recommending daily light therapy during the symptomatic months each year . We previously developed a SAD-tailored group cognitive-behavioral therapy ( CBT ) and tested its acute efficacy in 2 pilot studies . Here , we report an intent-to-treat ( ITT ) analysis of outcomes during the subsequent winter season ( i.e. , approximately 1 year after acute treatment ) using participants r and omized to CBT , light therapy , and combination treatment across our pilot studies ( N=69 ) . We used multiple imputation to estimate next winter outcomes for the 17 individuals who dropped out during treatment , were withdrawn from protocol , or were lost to follow-up . The CBT ( 7.0 % ) and combination treatment ( 5.5 % ) groups had significantly smaller proportions of winter depression recurrences than the light therapy group ( 36.7 % ) . CBT alone , but not combination treatment , was also associated with significantly lower interviewer- and patient-rated depression severity at 1 year as compared to light therapy alone . Among completers who provided 1-year data , all statistically significant differences between the CBT and light therapy groups persisted after adjustment for ongoing treatment with light therapy , antidepressants , and psychotherapy . If these findings are replicated , CBT could represent a more effective , practical , and palatable approach to long-term SAD management than light therapy
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 .