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 .
Light therapy for seasonal affective disorder in primary care: randomised controlled trial.
BACKGROUND Studies of light therapy have not been conducted previously in primary care . AIMS To evaluate light therapy in primary care . METHOD Fifty-seven participants with seasonal affective disorder were r and omly allocated to 4 weeks of bright white or dim red light . Baseline expectations for treatment were assessed . Outcome was assessed with the Structured Interview Guide for the Hamilton Depression Scale , Seasonal Affective Disorder Version . RESULTS Both groups showed decreases in symptom scores of more than 40 % . There were no differences in proportions of responders in either group , regardless of the remission criteria applied , with around 60 % ( 74 % white light , 57 % red light ) meeting broad criteria for response and 31 % ( 30 % white light , 33 % red light ) meeting strict criteria . There were no differences in treatment expectations . CONCLUSIONS Primary care patients with seasonal affective disorder improve after light therapy , but bright white light is not associated with greater improvements
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 .