Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .
A controlled trial of timed bright light and negative air ionization for treatment of winter depression.
BACKGROUND Artificial bright light presents a promising nonpharmacological treatment for seasonal affective disorder . Past studies , however , have lacked adequate placebo controls or sufficient power to detect group differences . The importance of time of day of treatment -- specifically , morning light superiority -- has remained controversial . METHODS This study used a morning x evening light crossover design balanced by parallel-group controls , in addition to a nonphotic control , negative air ionization .  Subjects with seasonal affective disorder ( N = 158 ) were r and omly assigned to 6 groups for 2 consecutive treatment periods , each 10 to 14 days . Light treatment sequences were morning-evening , evening-morning , morning-morning , and evening-evening ( 10,000 lux , 30 min/d ) . Ion density was 2.7 x 10(6 ) ( high ) or 1.0 x 10(4 ) ( low ) ions per cubic centimeter ( high-high and low-low sequences , 30 min/d in the morning ) . RESULTS Analysis of depression scale percentage change scores showed low-density ion response to be inferior to all other groups , with no other group differences . Response to evening light  was reduced when preceded by treatment with morning light , the sole sequence effect . Stringent remission criteria , however , showed significantly higher response to morning than evening light , regardless of treatment sequence . CONCLUSIONS Bright light and high-density negative air ionization both appear to act as specific antidepressants in patients with seasonal affective disorder . Whether clinical improvement would be further enhanced by their use in combination , or as adjuvants to medication , awaits investigation
Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .